Spinal cord injuries can be devastating and there are currentlyfew options to reverse the effects, which can include paralysis, chronic pain and loss of bladder control.

But an international team of researchers, including the University of Torontos Molly Shoichet,hopes to change that.

Over the past few years, weve made a lot of progress in tissue engineering, drug delivery and regenerative medicine, says Shoichet, a University Professor in the department of chemical engineering and applied chemistry in the Faculty of Applied Science & Engineering, the Institute of Biomedical Engineering and the Donnelly Centre for Cellular and Biomolecular Research.

With this ambitious project, we bring world leading experts together to try to do something that no one else has been able to do: promote repair and regeneration in the injured spinal cord.

Shoichet is a co-principal investigator withMend the Gap, an international collaboration of more than 30 researchers, engineers, scientists, surgeons and social scientists from Canada, the United States, Europe and Australia. The collaboration this week received $24 million from Canadas New Frontiers in Research Fund to advance their work.

The team takes its name from the fact that only a small gap, just a few centimetres long, is responsible for blocking the nerve impulses that normally flow through the spinal cord. Bridging that gap requires collaboration from some of the worlds top experts in a wide range of fields.

Shoichet is known internationally for her work on hydrogels biocompatible materials that can help facilitate tissue repair. Hydrogels can function as scaffolds, enhancing or augmenting natural processes that serve to repair damaged tissue.

Hydrogels can also serve as controlled-release mechanisms for drugs that aid healing, or to protect stem cells that are being injected into the body bykeeping them alive and healthy while they integrate into damaged tissues.

Another important line of research involves dealing with the glial scar that forms in the wake of a spinal cord injury. In the short term, this protective shield of cells and biochemicals prevents further injury in the damaged nerve, but in the long termit can serve as a barrier to nerve repair.

Shoichet and her team bring their expertise in hydrogels and local delivery strategies to deliver innovative biomolecules locally and directly to the injured spinal cord. For example, shere-engineered an enzymeto selectively degrade some of the biomolecules that make up the glial scar. This redesigned enzyme is both more stable and more active than the wild type.

By breaking through the glial scar with this new delivery strategy, the enzyme can enable other therapies from advanced drugs to stem cells to further promote tissue regeneration and repair.

The environment in the injured spinal cord is a very complicated place, says Shoichet. There are a whole range of natural processes at work some of which we want to enhance, others of which we need to find ways to circumvent. I am very excited to be part of this multidisciplinary team, which has the breadth and depth of expertise that we need to make a real difference when it comes to treating spinal cord injury.

Shoichet is the only person to be elected a fellow of all three of Canadas national academiesand is a foreign member of the U.S. National Academy of Engineering and a fellow of the Royal Society of London. She was the 2020 recipient of the Gerhard Herzberg Canada Gold Medal, Canadas highest honour for science and engineering research. She is also a member of the Order of Ontario and an Officer of the Order of Canada.

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Mending the gap: U of T's Molly Shoichet joins team developing new treatments for spinal cord injuries - News@UofT

In many ways, the human body is like any other machine in that it requires constant refueling and maintenance to keep functioning. Much of this happens without our intervention beyond us selecting what to eat that day. There are however times when due to an accident, physical illness or aging the automatic repair mechanisms of our body become overwhelmed, fail to do their task correctly, or outright fall short in repairing damage.

Most of us know that lizards can regrow tails, some starfish regenerate into as many new starfish as the pieces which they were chopped into, and axolotl can regenerate limbs and even parts of their brain. Yet humans too have an amazing regenerating ability, although for us it is mostly contained within the liver, which can regenerate even when three-quarters are removed.

In the field of regenerative medicine, the goal is to either induce regeneration in damaged tissues, or to replace damaged organs and tissues with externally grown ones, using the patients own genetic material. This could offer us a future in which replacement organs are always available at demand, and many types of injuries are no longer permanent, including paralysis.

Our level of understanding of human physiology and that of animals in general has massively expanded since the beginning of the 20th century when technology allowed us to examine the microscopic world in more detail than ever before. Although empirical medical science saw its beginnings as early as the Sumerian civilization of the 3rd millennium BCE, our generalized understanding of the processes and components that underlie the bodys functioning are significantly more recent.

DNA was first isolated in 1869 by Friedrich Miescher, but its structure was not described until 1953. This discovery laid the foundations for the field of molecular biology, which seeks to understand the molecular basis for biological activity. In a sense this moment can be seen as transformative as for example the transition from classical mechanics to quantum mechanics, in that it changed the focus from macroscopic observations to a more fundamental understanding of these observations.

This allowed us to massively increase our understanding of how exactly the body responds to damage, and the molecular basis for regenerative processes, as well as why humans are normally not able to regrow damaged limbs. Eventually in 1999 the term regenerative medicine was coined by William A. Haseltine, who wrote an article in 2001 on what he envisions the term to include. This would be the addressing of not only injuries and trauma from accidents and disease, but also aging-related conditions, which would address the looming demographic crisis as the average age of the worlds populations keeps increasing.

The state of the art in regenerative medicine back in 2015 was covered by Angelo S. Mao et al. (2015). This covers regenerative methods involving either externally grown tissues and organs, or the stimulating of innate regenerative capabilities. Their paper includes the biomedical discipline of tissue engineering due to the broad overlap with the field of regenerative medicine. Despite the very significant time and monetary requirement to bring a regenerative medicine product to market, Mao et al. list the FDA-approved products at that time:

While these were not miracle products by any stretch of the imagination, they do prove the effectiveness of these approaches, displaying similar or better effectiveness as existing products. While getting cells to the affected area where they can induce repair is part of the strategy, another essential part involves the extracellular matrix (ECM). These are essential structures of many tissues and organs in the body which provide not only support, but also play a role in growth and regeneration.

ECM is however non-cellular, and as such is seen as a medical device. They play a role in e.g. the healing of skin to prevent scar tissue formation, but also in the scaffolding of that other tantalizing aspect of regenerative medicine: growing entire replacement organs and body parts in- or outside of the patients body using their own cells. As an example, Mase Jr, et al. (2010) report on a 19-year old US Marine who had part of his right thigh muscle destroyed by an explosion. Four months after an ECM extracted from porcine (pig) intestinal submucossa was implanted in the area, gradual regrowth of muscle tissue was detected.

An important research area here is the development of synthetic ECM-like scaffolding, as this would make the process faster, easier and more versatile. Synthetic scaffolding makes the process of growing larger structures in vitro significantly easier as well, which is what is required to enable growing organs such as kidneys, hearts and so on. These organs would then ideally be grown from induced pluropotent stem cells (iPS), which are a patients own cells that are reverted back to an earlier state of specialization.

It should come as little surprise that as a field which brings together virtually every field that touches upon (human) biology in some fashion, regenerative medicine is not an easy one. While its one thing to study a working system, its a whole different level to get one to grow from scratch. This is why as great as it would be to have an essentially infinite supply of replacement organs by simply growing new ones from iPS cells, the complexity of a functional organ makes this currently beyond our reach.

Essentially the rule is that the less complicated the organ or tissue is, the easier it is to grow it in vitro. Ideally it would just consist out of a single type of cell, and happy develop in some growth medium without the need for an ECM. Attractive targets here are for example the cornea, where the number of people on a waiting list for a corneal transplant outnumber donor corneas significantly.

In a review by Mobaraki et al. (2019), the numerous currently approved corneal replacements as well as new methods being studied are considered. Even though artificial corneas have been in use for years, they suffer from a variety of issues, including biocompatibility issues and others that prevent long-term function. Use of donor corneas comes with shortages as the primary concern. Current regenerative research focuses on the stem cells found in the limbus zone (limbal stem cells, LSC). These seem promising for repairing ocular surface defects, which has been studied since 1977.

LSCs play a role in the regular regenerative abilities of the cornea, and provide a starting point for either growing a replacement cornea, or to repair a damaged cornea, along with the addition of an ECM as necessary. This can be done in combination with the inhibiting of the local immune response, which promotes natural wound healing. Even so, there is still a lot more research that needs to be performed before viable treatments for either repairing the cornea in situ, or growing a replacement in vitro can be approved the FDA or national equivalent.

A similar scenario can be seen with the development of artificial skin, where fortunately due to the large availability of skin on a patients body grafts (autografts) are usually possible. Even so, the application of engineered skin substitutes (ESS) would seem to be superior. This approach does not require the removal of skin (epidermis) elsewhere, and limits the amount of scar formation. It involves placing a collagen-based ECM on the wound, which is optionally seeded with keritanocytes (skin precursor cells), which accelerates wound closure.

Here the scaffolding proved to be essential in the regeneration of the skin, as reported by Tzeranis et al. (2015). This supports the evidence from other studies that show the cell adhesion to the ECM to be essential in cell regulation and development. With recent changes, it would seem that both the formation of hair follicles and nerve innervation may be solved problems.

It will likely still be a long time before we can have something like a replacement heart grown from a patients own iPS cells. Recent research has focused mostly on decellularization (leaving only the ECM) of an existing heart, and repopulating it with native cells (e.g. Glvez-Montn et al., 2012). By for example creating a synthetic scaffold and populating it with cells derived from a patients iPS cells, a viable treatment could be devised.

Possibly easier to translate into a standard treatment is the regrowth of nerves in the spinal cord after trauma, with a recent article by lvarez et al, (2021) (press release) covering recent advances in the use of artificial scaffolds that promotes nerve regeneration, reduces scarring and promotes blood vessel formation. This offers hope that one day spinal cord injures may be fully repairable.

If we were to return to the body as a machine comparison, then the human body is less of a car or piece of heavy machinery, and more of a glued-together gadget with complex circuitry and components inside. With this jump in complexity comes the need for a deeper level of understanding, and increasingly more advanced tools so that repairs can be made efficiently and with good outcomes.

Even so, regenerative medicine is already saving the lives of for example burn victims today, and improving the lives of countless others. As further advances in research continue to translate into treatments, we should see a gradual change from youll have to learn to live with that, to a more optimistic give it some time to grow back, as in the case of an injured veteran, or the victim of an accident.

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Regenerative Medicine: The Promise Of Undoing The Ravages Of Time - Hackaday

After the therapy performs its function, the materials biodegrade into nutrients for the cells within 12 weeks and then completely disappear from the body without noticeable side effects.This is the first study in which researchers controlled the collective motion of molecules through changes in chemical structure to increase a therapeutics efficacy.

Samuel I. Stupp

Our research aims to find a therapy that can prevent individuals from becoming paralyzed after major trauma or disease, said NorthwesternsSamuel I. Stupp, who led the study. For decades, this has remained a major challenge for scientists because our bodys central nervous system, which includes the brain and spinal cord, does not have any significant capacity to repair itself after injury or after the onset of a degenerative disease. We are going straight to the FDA to start the process of getting this new therapy approved for use in human patients, who currently have very few treatment options.

Stupp is Board of Trustees Professor of Materials Science and Engineering, Chemistry, Medicine and Biomedical Engineering at Northwestern, where he is founding director of theSimpson Querrey Institute for BioNanotechnology(SQI) and its affiliated research center, theCenter for Regenerative Nanomedicine. He has appointments in theMcCormick School of Engineering,Weinberg College of Arts and SciencesandFeinberg School of Medicine.

According to the National Spinal Cord Injury Statistical Center, nearly 300,000 people are currently living with a spinal cord injury in the United States. Life for these patients can be extraordinarily difficult. Less than 3% of people with complete injury ever recover basic physical functions. And approximately 30% are re-hospitalized at least once during any given year after the initial injury, costing millions of dollars in average lifetime health care costs per patient. Life expectancy for people with spinal cord injuries is significantly lower than people without spinal cord injuries and has not improved since the 1980s.

I wanted to make a difference on the outcomes of spinal cord injury and to tackle this problem, given the tremendous impact it could have on the lives of patients.

Currently, there are no therapeutics that trigger spinal cord regeneration, said Stupp, an expert in regenerative medicine. I wanted to make a difference on the outcomes of spinal cord injury and to tackle this problem, given the tremendous impact it could have on the lives of patients. Also, new science to address spinal cord injury could have impact on strategies for neurodegenerative diseases and stroke.

A new injectable therapy forms nanofibers with two different bioactive signals (green and orange) that communicate with cells to initiate repair of the injured spinal cord. Illustration by Mark Seniw

The secret behind Stupps new breakthrough therapeutic is tuning the motion of molecules, so they can find and properly engage constantly moving cellular receptors. Injected as a liquid, the therapy immediately gels into a complex network of nanofibers that mimic the extracellular matrix of the spinal cord. By matching the matrixs structure, mimicking the motion of biological molecules and incorporating signals for receptors, the synthetic materials are able to communicate with cells.

Receptors in neurons and other cells constantly move around, Stupp said. The key innovation in our research, which has never been done before, is to control the collective motion of more than 100,000 molecules within our nanofibers. By making the molecules move, dance or even leap temporarily out of these structures, known as supramolecular polymers, they are able to connect more effectively with receptors.

100,000molecules move within the nanofibers

Stupp and his team found that fine-tuning the molecules motion within the nanofiber network to make them more agile resulted in greater therapeutic efficacy in paralyzed mice. They also confirmed that formulations of their therapy with enhanced molecular motion performed better during in vitro tests with human cells, indicating increased bioactivity and cellular signaling.

Given that cells themselves and their receptors are in constant motion, you can imagine that molecules moving more rapidly would encounter these receptors more often, Stupp said. If the molecules are sluggish and not as social, they may never come into contact with the cells.

Once connected to the receptors, the moving molecules trigger two cascading signals, both of which are critical to spinal cord repair. One signal prompts the long tails of neurons in the spinal cord, called axons, to regenerate. Similar to electrical cables, axons send signals between the brain and the rest of the body. Severing or damaging axons can result in the loss of feeling in the body or even paralysis. Repairing axons, on the other hand, increases communication between the body and brain.

Zaida lvarez

The second signal helps neurons survive after injury because it causes other cell types to proliferate, promoting the regrowth of lost blood vessels that feed neurons and critical cells for tissue repair. The therapy also induces myelin to rebuild around axons and reduces glial scarring, which acts as a physical barrier that prevents the spinal cord from healing.

The signals used in the study mimic the natural proteins that are needed to induce the desired biological responses. However, proteins have extremely short half-lives and are expensive to produce, said Zaida lvarez, the studys first author. Our synthetic signals are short, modified peptides that when bonded together by the thousands will survive for weeks to deliver bioactivity. The end result is a therapy that is less expensive to produce and lasts much longer.

A former research assistant professor in Stupps laboratory,lvarez is now a visiting scholar at SQI and a researcher at theInstitute for Bioengineering of Catalonain Spain.

While the new therapy could be used to prevent paralysis after major trauma (automobile accidents, falls, sports accidents and gunshot wounds) as well as from diseases, Stupp believes the underlying discovery that supramolecular motion is a key factor in bioactivity can be applied to other therapies and targets.

The central nervous system tissues we have successfully regenerated in the injured spinal cord are similar to those in the brain affected by stroke and neurodegenerative diseases, such as ALS, Parkinsons disease and Alzheimers disease, Stupp said. Beyond that, our fundamental discovery about controlling the motion of molecular assemblies to enhance cell signaling could be applied universally across biomedical targets.

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Cardiac muscle cells or cardiomyocytes (also known as cardiac myocytes) are the muscle cells (myocytes) that make up the heart muscle. Cardiomyocytes go through a contraction-relaxation cycle that enables cardiac muscles to pump blood throughout the body.

[In this image] Immunostaining of human cardiomyocytes with antibodies for actin (red), myomesin (green), and nuclei (blue).Photo source: https://www.fujifilmcdi.com/products/cardiac-cells/icell-cardiomyocytes

Cardiomyocytes are highly specialized cell types in terms of their structures and functions. Each cardiomyocyte contains myofibrils, unique organelles consisting of long chains of sarcomeres, the fundamental contractile units of muscle cells.

[In this image] Cardiomyocyte geometry and cellular architecture are controlled by micropatterned ECM substrate. Scientists used this technique to study how cells sense and respond to mechanical forces.Photo source: https://diseasebiophysics.seas.harvard.edu/research/mechanotransduction/

The heart is a muscular organ that pumps blood through the blood vessels of the circulatory system. It is composed of individual heart muscle cells (cardiomyocytes) and several other cell types.

[In this figure] The anatomy of the human heart showing 4 heart chambers (left atrium, left ventricle, right atrium, right ventricle) and the blood flow. The myocardium is referred to the cardiac muscle layers building the wall of each chamber.

[In this figure] The thickness of the heart wall (or myocardium) consists of cardiac muscle cells.Photo source: biologydictionary

[In this video] Structure of the human heart.

Cardiovascular disease is a leading cause of death worldwide. Nearly 2,400 Americans die of cardiac causes each day, one death every 37 seconds.

As the chief cell type of the heart, cardiac muscle cells primarily dedicate to the contractile function of the heart and enable the pumping of blood around the body. If anything goes wrong in the heart, it can lead to a catastrophic outcome. A myocardial infarction (MI), commonly known as a heart attack, occurs when blood flow ceases to a part of the heart, causing massive cardiomyocyte death in that area. Severe cases can, ultimately, lead to heart failure and death.

[In this figure] The progress of myocardial infarction or heart attack. At time post-infarction:

0-12 hours: Beginning of necrotic coagulation due to the blockage of coronary arteries Cardiomyocytes suffer the lack of oxygen (hypoxia)

12-72 hours: Culmination of necrotic coagulation Neutrophils infiltrate by an inflammatory response.

1-3 weeks: Disintegration of death myocytes and formation of granulation tissue (collagenous fibers, macrophages, and fibroblasts)

> 1 month: Formation of fibrous scar (fewer cells with an abundance of collagenous fibers)

A human heart contains an estimated 23 billion cardiomyocytes. There are several non-myocyte populations in the heart, including endothelial cells, smooth muscle cells, myofibroblasts, epicardial cells, endocardial cells, valve interstitial cells, resident macrophages, and other immune system-related cells, and potentially, adult stem cells (mesenchymal stem cells and cardiac stem cells). These distinct cell pools are not isolated from one another within the heart but interact physically to maintain the function of the whole organ. Overall, cardiomyocytes only account for less than a third of the total cell number in the heart.

[In this image] Immunostaining showing highly vascularized heart muscle.Cardiomyocytes are labeled by the striated pattern of sarcomeric -actinin (green). Capillaries are red and nuclei are blue.Photo source: biocompare.

The three main types of muscle include: Cardiac muscle, Skeletal muscle, and Smooth muscle.

[In this figure] Morphology and comparison of cardiac, skeleton, and smooth muscles.

Note: Involuntary muscles are the muscles that cannot be controlled by will or conscious.

There are two types of cells within the heart: the cardiomyocytes and the cardiac pacemaker cells.

The heart is composed of cardiac muscle cells that have specialized features that relate to their function:

These structural features contribute to the unique functional properties of the cardiac tissue:

Like other animal cells, cardiomyocytes contain all the cell organelles that are essential for normal cell physiology. Moreover, cardiomyocytes have several unique cellular structures that allow them to perform their function effectively. Here are five main characteristics of mature cardiomyocytes: (1) striated; (2) uninucleated; (3) branched; (4) connected by intercalated discs; (5) high mitochondrial content.

[In this figure] Main characteristics of cardiac myocytes.Modified from lumen Anatomy and Physiology I.

Lets get closer to look inside a cardiomyocyte and learn its unique ultrastructure.

All cardiomyocytes and pacemaker cells are linked by cellular bridges. Intercalated discs, which form porous junctions, bring the membranes of adjacent cardiomyocytes very close together. These pores (gap junctions) permit ions, such as sodium, potassium, and calcium, to easily diffuse from cell to cell, establishing a cell-cell communication. This joining is called electric coupling, and it allows the quick transmission of action potentials and the coordinated contraction of the entire heart.

Intercalated discs also function as mechanical anchor points that enable the transmission of contractile force from one cardiomyocyte to another (by desmosomes and adherens junctions). This allows for the heart to work as a single coordinated unit.

[In this figure] Cardiac muscle cells are connected together to coordinate the cardiac contraction. This joining is called electric coupling and is achieved by the presence of irregularly-spaced dark bands between cardiomyocytes. These bands are known as intercalated discs.Photo source: bioninja.

[In this figure] Cardiac myocytes are branched and interconnected from end to end by structures called intercalated disks, visible as dark lines in the light microscope.Photo source: https://doctorlib.info/physiology/medical/49.html

There are 3 main types of junctional complexes within the intercalated discs. They work in different ways to maintain cardiac tissue integrity and cardiomyocyte synchrony.

The term desmosome came from Greek words of bonding (desmo) and body (soma). Desmosomes serve as the anchor points to bring the cardiac muscle fibers together. Desmosomes can withstand mechanical stress, which allows them to hold cells together. Without desmosomes, the cells of the cardiac muscles will fall apart during contraction.

The ability of desmosome to resist mechanical stress comes from its unique 3-D structure. Desmosome is an asymmetrical protein complex bridging between two adjacent cardiomyocytes, with each end residing in the cytoplasm. The intracellular part anchors intermediate filaments in the cytoskeleton to the cell surface. The middle part bridges the intercellular space between two cytoplasmic membranes.

[In this figure] Desmosomes connect intermediate filaments from two adjust cardiomyocytes. This job is accomplished by the formation of a dense protein complex or plaque in the intercalated discs. Major protein players include transmembrane cadherins: desmogleins (Dsgs) and desmocollins (Dscs), cytoplasmic anchors: plakophilins (PKPs) and plakoglobin (PG), and cytoskeleton adaptor: desmoplakin (DP). Cadherins link cells together, and other proteins form a dense complex called plaque.

In addition to desmosomes, adherens junctions (Ajs) are another type of mechanical intercellular junctions in cardiomyocytes. The difference is that adherens junctions link the intercalated disc to the actin cytoskeleton and desmosomes attach to intermediate filaments.

Adherens junctions keep the cardiac muscle cells tightly together as the heart pump. Adherens junctions are also the anchor point where myofibrils are attached, enabling transmission of contractile force from one cell to another.

[In this figure] Adherens junctions link actin cytoskeleton from two adjust cardiomyocytes together.Adherens junctions are constructed from cadherins and catenins. Cadherins (in cardiomyocytes N-Cadherin is the main cadherin) are transmembrane proteins that zip together adjacent cells in a homophilic manner. The transmembrane cadherins form complexes with cytosolic catenins, thereby establishing the connection to the actin cytoskeleton. At the adherens junctions, the opposing membranes become separated by 20nm.

Gap junctions are essential for the chemical and electrical coupling of neighboring cells. Gap junctions work like intercellular channels connecting the cytoplasm of neighboring cells, enabling passive diffusion of various compounds, like metabolites, water, and ions, up to a molecular mass of 1000 Da. Thereby they establish direct communication between adjacent cells.

[In this figure] Neonatal rat cardiac myocytes in cell culture.Cells were immunostained for actinin (green), gap junctions (red), and counterstained with DAPI (blue).Photo source: bioscience

Gap junctions are present in nearly all tissues and cells throughout the entire body. In cardiac muscle, gap junctions ensure proper propagation of the electrical impulse (from pacemaker cells to neighboring cardiomyocytes). This electrical wave triggers sequential and coordinated contraction of the cardiomyocytes as a whole.

[In this figure] A gap junction channel consists of twelve connexin proteins, six of which are contributed by each cell. The six connexin subunits form a hemi-channel in the plasma membrane, which is called a connexon. A connexon docks to another connexon in the intercellular space to create a complete gap junction channel. The intercellular space between adjacent cells at the site of a gap junction is 2-4 nm.

A second feature of cardiomyocytes is the sarcomeres, which are also present in skeletal muscles. The sarcomeres give cardiac muscle their striated appearance and are the repeating sections that make up myofibrils.

[In this image] Freshly isolated heart muscle cells showing intercalated discs (green), sarcomeres (red), and nuclei (blue).Photo source: https://christianz.artstation.com/

Cardiac muscle cells are equipped with bundles of myofibrils that contain myofilaments. These fiber-like structures can occupy 45-60% of the volume of cardiomyocytes. The myofibrils are formed of distinct, repeating units, termed sarcomeres. The sarcomeres, which are composed of thick and thin myofilaments, represent the basic contractile units of a muscle cell and are defined as the region of myofilament structures between two Z-lines (see image below). The distance between Z-lines in human hearts ranges from around 1.6 to 2.2 m.

[In this figure] Labeled diagram of myofibril showing the unit of a sarcomere. A sarcomere is defined as a segment between two neighboring Z-discs.

[In this image] Immunofluorescence image of adult mouse cardiomyocytes showing the Z-lines of the sarcomeres. 3D color projection of alpha-actinin 2 acquired with a confocal microscope.Photo source: Dylan Burnette.

The thick filaments are composed of myosin II. Each myosin contains two ATPase sites on its head. ATPase hydrolyzes ATP and this process is required for actin and myosin cross-bridge formation. These heads bind to actin on the thin filaments. There are about 300 molecules of myosin per thick filament.

The thin filaments are composed of single units of actin known as globular actin (G-actin). Two strands of actin filaments form a helix, which is stabilized by rod-shaped proteins termed tropomyosin. Troponin proteins, which function as regulators, bind to the tropomyosin at regular intervals. Whereas troponin lies in the grooves between the actin filaments, tropomyosin covers the sites on which actin binds to myosin. Their respective actions, therefore, control the binding of myosin to actin and consequently in the contraction and relaxation of cardiac muscles.

To generate muscular contraction, the myosin heads bind to actin filaments, allowing myosin to function as a motor that drives filament sliding. The actin filaments slide past the myosin filaments toward the middle of the sarcomere. This results in the shortening of the sarcomere without any change in filament length.

[In this figure] Sliding-filament model of muscle contraction.

Sarcolemma (also called myolemma) is a specialized cell membrane of cardiomyocytes and skeletal muscle cells. It consists of a lipid bilayer and a thin outer coat of polysaccharide material (glycocalyx) that contacts the basement membrane. The sarcolemma is also part of the intercalated disks as well as the T-tubules of the cardiac muscle.

Basement membrane is an extracellular matrix (ECM) coat that cover individual cardiomyocytes. Its composed of glycoproteins laminin and fibronectin, type IV collagen as well as proteoglycans that contribute to its overall width of about 50nm. Basement membrane provides a scaffold to which the muscle fiber can adhere.

[In this figure] A cross-section of a mouse heart showing the basement membrane (green) wrapping around an individual myocyte.

In cardiomyocytes and skeletal muscle cells, the sarcolemma (i.e. the plasma membrane) forms deep invaginations known as T-tubules (or transverse tubules). These invaginations increase the total surface area and allow depolarization of the membrane to penetrate quickly to the interior of the cell.

Without t-tubules, the wave of calcium ions (Ca2+) takes time to propagate from the periphery of the cell into the center. This time lag will first activate the peripheral sarcomeres and then the deeper sarcomeres, resulting in sub-maximal force production.

The t-tubules make it possible that current is simultaneously relayed to the core of the cell, and trigger near to all sarcomeres simultaneously, resulting in a maximal force output. T-tubules also stay close to sarcoplasmic reticulum (SR) networks, which is the modified endoplasmic reticulum (ER) of calcium storage in myocytes.

[In this figure] T-tubules (transverse tubules) are extensions of the cell membrane that penetrate into the center of skeletal and cardiac muscle cells. T-tubules permit the rapid transmission of the action potential into the cell and also play an important role in regulating cellular calcium concentration.

Mitochondria are the powerhouse of the cell because they generate most of the cells energy supply of adenosine triphosphate (ATP). It is no doubt that the normal functions of cardiomyocytes require a lot of energy. Effective heart pumping is primarily dependent on oxidative energy production by mitochondria. Cardiomyocytes have a densely packed mitochondrial network, which allows them to produce ATP quickly, making them highly resistant to fatigue.

Different types of mitochondria can be distinguished within cardiomyocytes, and their morphological features are usually defined according to their location: intermyofibrillar mitochondria, subsarcolemmal mitochondria, and perinuclear mitochondria.

[In this figure] Mitochondrial morphology in cardiomyocytes.(Top) The anatomy of a mitochondrion. (Bottom left) Schematic diagram of the location of subsarcolemmal mitochondria (SSM), interfibrillar mitochondria (IFM), and perinuclear mitochondria (PNM). (Bottom right) TEM images of mitochondria in cardiomyocytes.Photo source: researchgate, wiki

Intermyofibrilar Mitochondria are found deeper within the cells and strictly ordered between rows of contractile proteins, apparently isolated from each other by repeated arrays. They play a huge role in producing enough energy for muscle contractions.

[In this figure] Immunofluorescent confocal imaging showing the densely packed mitochondria in cardiomyocytes. (A): Z-line (actinin); (B): Mitochondria; (C): Merge image.Photo source: MDPI

Subsarcolemmal Mitochondria reside beneath the sarcolemma. They collect oxygen from the circulating blood in the arteries and are responsible for providing the energy needed for conserving the integrity of the sarcolemma.

Perinuclear mitochondria are organized in clusters around the nucleus to provide energy for transcription and translation processes.

The cardiac function requires high energy demands; therefore, the adult cardiomyocytes contain numerous mitochondria, which can occupy at least 30% of cell volume. They meet >90% of the energy requirements by oxidative phosphorylation (OXPHOS) in the mitochondria, which requires a huge demand for oxygen consumption.

In humans, at a heart rate of 6070 beats per minute, the oxygen consumption of the myocardium is 20-fold higher than that of skeletal muscle at rest (compared by a normalization per gram of cell mass). In order to meet this high oxygen demand, the capillary density in the heart is 2-8 times higher than that in skeletal muscle (3,0004,000/mm2 compared to 5002,000 capillaries/mm2, respectively). Also, cardiomyocytes maintain a very high level of oxygen extraction (from blood) of 7080% compared with 3040% in skeletal muscle.

[In this image] Myofibrils in cultured cardiomyocytes.Photo source: https://christianz.artstation.com/

Cardiomyocytes go through a contraction-relaxation cycle that enables cardiac muscles to pump blood throughout the body. This is achieved through a process known as excitation-contraction coupling (ECC) that converts action potential (an electric stimulus) into muscle contraction.

[In this figure] Schematic diagram of the process of cardiac excitation-contraction coupling.Key steps in the cardiac excitation-contraction coupling:

Step 1: An action potential is induced by pacemaker cells. It travels along the sarcolemma and down into the T-tubule system to depolarize the cell membrane.

Step 2: Calcium channels in the T-tubules are activated by the action potential and permit calcium entry into the cell.

Step 3: Calcium influx triggers a subsequent release of calcium that is stored in the sarcoplasmic reticulum (SR).

Step 4: Free calcium binds troponin-C (TN-C) that is part of the regulatory complex attached to the thin filaments. Calcium binding moves the troponin complex from the actin binding site. As a result, actin is free to bind myosin. The actin and myosin filaments slide past each other thereby shortening the sarcomere length, thus initiating contraction.

Step 5: At the end of a contraction, calcium entry into the cell slows and calcium is sequestered by the SR by calcium pumps. Lowering the cytosolic calcium concentration releases myosin-actin binding and the initial sarcomere length is restored.

In human beings (and many other animals), cardiomyocytes are the first cells to terminally differentiate, thus making the heart one of the first organs to form in a developing fetus. This makes sense because the function of the circulatory system is so crucial for a growing embryo so that the heart is the top priority.

In the embryo of a mouse, for instance, precursor cells of the cardiac muscles have been shown to start developing about 6 days after fertilization. In human embryos, the heart begins to beat at about 22-23 days, with blood flow beginning in the 4th week. The heart is therefore one of the earliest differentiating and functioning organs.

The heart forms initially in the embryonic disc as a simple paired tube (heart tube formation; week 3) derived from mesoderm. Then, the heart tubes loop and begin segmenting to separate chambers primitive atrium, and primitive ventricle. During this period, the first heartbeat begins.

[In this figure] The timeline of heart development.LA means left atrium; RA means right atrium. For more details, seehttps://embryology.med.unsw.edu.au/embryology/index.php/Cardiovascular_System_-_Heart_Development

Here, cardiomyocytes grow into a spongy-like tissue (cardiac jelly), called trabeculation, to build up the thickness of myocardial muscles. Thus, the heart begins to resemble the adult heart in that it has two atria, two ventricles, and the aorta forming a connection with the left ventricle while the pulmonary trunk forms a connection with the right ventricle.

As you can see that our hearts went through a complex developmental process. Inevitably, heart developmental abnormalities could happen (affect 8-10 of every 1000 births in the United States).

Can cardiomyocytes divide? Scientists used to believe that damaged human cardiac muscles cannot regenerate themselves by cell division in adults. In other words, all cardiomyocytes are terminally differentiated. In humans, our cardiomyocytes lose the ability to divide at around 7 days after birth. However, studies have recently shown that myocytes renew at a significantly low rate throughout the life of an individual. For instance, for younger people, about 25 years of age, the annual turnover of cardiomyocytes is about 1 percent. This, however, decreases to about 0.45 percent for older individuals (75 and above). Over the lifespan of an individual, less than 50 percent of these cells are renewed. Comparing to many of the other cells, cardiomyocytes have a very long lifespan. In contrast, small intestine epithelium renews every 2-7 days and hepatocytes (liver cells) renew every 0.5-1 year.

[In this figure] Radiocarbon dating establishes the age of human cardiomyocytes.Scientists used a pretty smart way to estimate the turnover of human heart cells. Generally speaking, the half-life of 14C is too long to date a lifetime of less than a century. However, the dramatic increase in the atmospheric 14C caused by nuclear bomb tests (during the Cool War) in the 1950s and 1960s increased the sensitivity of radiocarbon dating to a temporal resolution of 1-2years.Photo source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5837331/

Low turnover of human cardiomyocytes suggests that the regenerative ability of cardiac muscles may be poor (another example is neural cells in the brain). In the event of injuries or myocardial infarction, the injured heart muscles of human beings do not regenerate sufficiently to allow the heart to heal itself. Instead, fibrotic scar tissue forms in the injured site (fibrosis), and the heart functions are compromised, leading to heart failure.

Currently, a number of methods have been studied to repair a broken heart by regenerating cardiomyocytes. These new inventions benefit from the recent advances in biotechnology, especially stem cell biology, regenerative medicine, and tissue engineering. Hopefully, this can bring new therapeutic options to patients with cardiovascular diseases in the near future.

Studies suggested that even in adults, a very small population of progenitor cells reside in the heart and are capable of producing new cardiac myocytes. These cells, known as cardiac stem cells, may not be able to regenerate fast enough to repair a large area of damaged myocardium naturally in humans. However, these cells have shown to be powerful in regenerative capability in other species, like zebrafish.

Scientists believe that once we understand these cardiac progenitors more, we may isolate and expand these cells in quantity, and transplant them to repair damaged heart tissues. For example, we already learned that these cardiac stem cells express cell surface markers like c-Kit (sca-1 in mouse) and aggregate into cardiac spheres.

[In this figure] Multiple different stem cell populations have been described in the adult heart, including c-Kit and Sca-1 cells that were shown to be cardiac progenitors.Photo source: https://dev.biologists.org/content/143/8/1242

Induced pluripotent stem cell (iPSC) technology is a huge revolution in biotechnology. Patients cells (easily obtained from skin biopsy or even urine) can be converted into powerful pluripotent stem cells that have unlimited proliferation capacity and can differentiate any cell type of our body. This eliminates the need to use human embryos for this purpose. Furthermore, these cells are autologous, meaning they wont be rejected by the immune system after transplantation.

Using iPSC technology, researchers have been able to obtain unlimited amounts of functional cardiomyocytes for cell transplantation. Basically, they control the Wnt pathway to convert iPSCs to mesodermal progenitor cells, then play with several growth factors to direct the cardiac vascular progenitors (Flk1+). Following glucose starvation, pure cardiomyocytes can be selected. You can even see these cells beating in the dish.

Therapeutic implantation of iPSC-derived cardiomyocytes progresses pretty fast. We already witnessed successful cell engraftment and cardiac repairing in non-human primates and human patients.

[In this video] Heart cells derived from iPSC stem cells beating in a cell culture dish.

Cardiac fibroblasts make up a significant portion of the total cardiac cells. In the injured heart, these fibroblasts will become active myofibroblasts and form scar tissue. Myofibroblasts survive very well and have ability to coupled with neighboring cells; therefore, myofibroblasts have been shown to be particularly ideal for direct reprogramming to convert them into cells that resemble cardiomyocytes.

Over the past decade, a number of studies have been successfully conducted, reprogramming fibroblasts into cardiomyocyte-like cells. In principle, scientists expressed transcription factors (i.e., Gata4, Mef2c, and Tbx5) that play critical roles in cardiomyocyte differentiation to force the conversion of fibroblasts. Ideally, these genes can be delivered directly to the injured heart via viruses or nanoparticles to perform in situ reprogramming.

Scientists also put their efforts into how to stimulate mature cardiomyocytes to proliferate again (Mature cardiomyocytes typically do not proliferate.) This strategy, called cell cycle re-entry, recently gained success by screening many cell-cycle regulators. Scientists found a combination of cyclin-dependent kinases (CDK) and cyclins, or regulators of the Hippo-YAP signaling pathway can do so. These findings reveal the possibility to efficiently unlock the proliferative potential in cells that had terminally exited the cell cycle.

[In this figure] Potential cardiac regenerative therapies.Photo source: https://www.nature.com/articles/s41536-017-0024-1

Cardiomyocytes can be observed by staining of histological sections of the heart. Since the heart is a 3-D organ, make sure you cut the heart at the right angle.

[In this figure] (Left) A longitudinal section through both ventricles should be made from the base to the apex of the heart. (Right) A cross-section of the heart. H&E staining.(Ao: aorta, At: atrium, Lv: left ventricle, Rv: right ventricle)

Common histological staining for heart tissues includes Hematoxylin and eosin (H&E) and Massons trichrome staining.

[In this figure] A cross section of mouse heart stained by Massons trichrome. Blue color indicates the formation of fibrous scar tissues in the infarction area.

Read more from the original source:
Cardiomyocytes (Cardiac Muscle Cells) - Structure ...

Introduction

Given the multi-lineage differentiation abilities of mesenchymal stem cells (MSCs) isolated from different tissues and organs, MSCs have been widely used in various medical fields, particularly regenerative medicine.13 The representative sources of MSCs are bone marrow, adipose, periodontal, muscle, and umbilical cord blood.410 Interestingly, slight differences have been reported in the characteristics of MSCs depending on the different sources, including their population in source tissues, immunosuppressive activities, proliferation, and resistance to cellular aging.11 Bone marrow-derived MSCs (BM-MSCs) are the most intensively studied and show clinically promising results for cartilage and bone regeneration.11 However, the isolation procedures for BM-MSCs are complicated because bone marrow contains a relatively small fraction of MSCs (0.0010.01% of the cells in bone marrow).12 Furthermore, bone marrow aspiration to harvest MSCs in human bones is a painful procedure and the slower proliferation rate of BM-MSCs is a clinical limitation.13 In comparison with BM-MSCs, adipose-derived MSCs (AD-MSCs) are relatively easy to collect and can produce up to 500 times the cell population of BM-MSCs.14 AD-MSCs showed a greater ability to regenerate damaged cartilage and bone tissues with increased immunosuppressive ability.14,15 Umbilical cord blood-derived MSCs (UC-MSCs) proliferate faster than BM-MSCs and are resistant to significant cellular aging.11

MSCs have been investigated and gained worldwide attention as potential therapeutic candidates for incurable diseases such as arthritis, spinal cord injury, and cardiac disease.3,1623 In particular, the inherent tropism of MSCs to inflammatory sites has been thoroughly studied.24 This inherent tropism, also known as homing ability, originates from the recognition of various chemokine sources in inflamed tissues, where profiled chemokines are continuously secreted and the MSCs migrate to the chemokines in a concentration-dependent manner.24 Rheumatoid arthritis (RA) is a representative inflammatory disease that primarily causes inflammation in the joints, and this long-term autoimmune disorder causes worsening pain and stiffness following rest. RA affects approximately 24.5 million people as of 2015, but only symptomatic treatments such as pain medications, steroids, and nonsteroidal anti-inflammatory drugs (NSAIDs), or slow-acting drugs that inhibit the rapid progression of RA, such as disease-modifying antirheumatic drugs (DMARDs) are currently available. However, RA drugs have adverse side effects, including hepatitis, osteoporosis, skeletal fracture, steroid-induced arthroplasty, Cushings syndrome, gastrointestinal (GI) intolerance, and bleeding.2527 Thus, MSCs are rapidly emerging as the next generation of arthritis treatment because they not only recognize and migrate toward chemokines secreted in the inflamed joints but also regulate inflammatory progress and repair damaged cells.28

However, MSCs are associated with many challenges that need to be overcome before they can be used in clinical settings.2931 One of the main challenges is the selective accumulation of systemically administered MSCs in the lungs and liver when they are administered intravenously, leading to insufficient concentrations of MSCs in the target tissues.32,33 In addition, most of the administered MSCs are typically initially captured by macrophages in the lungs, liver, and spleen.3234 Importantly, the viability and migration ability of MSCs injected in vivo differed from results previously reported as favorable therapeutic effects and migration efficiency in vitro.35

To improve the delivery of MSCs, researchers have focused on chemokines, which are responsible for MSCs ability to move.36 The chemokine receptors are the key proteins on MSCs that recognize chemokines, and genetic engineering of MSCs to overexpress the chemokine receptor can improve the homing ability, thus enhancing their therapeutic efficacy.37 Genetic engineering is a convenient tool for modifying native or non-native genes, and several technologies for genetic engineering exist, including genome editing, gene knockdown, and replacement with various vectors.38,39 However, safety issues that prevent clinical use persist, for example, genome integration, off-target effects, and induction of immune response.40 In this regard, MSC mimicking nanoencapsulations can be an alternative strategy for maintaining the homing ability of MSCs and overcoming the current safety issues.4143 Nanoencapsulation involves entrapping the core nanoparticles of solids or liquids within nanometer-sized capsules of secondary materials.44

MSC mimicking nanoencapsulation uses the MSC membrane fraction as the capsule and targeting molecules, that is chemokine receptors, with several types of nanoparticles, as the core.45,46 MSC mimicking nanoencapsulation consists of MSC membrane-coated nanoparticles, MSC-derived artificial ectosomes, and MSC membrane-fused liposomes. Nano drug delivery is an emerging field that has attracted significant interest due to its unique characteristics and paved the way for several unique applications that might solve many problems in medicine. In particular, the nanoscale size of nanoparticles (NPs) enhances cellular uptake and can optimize intracellular pathways due to their intrinsic physicochemical properties, and can therefore increase drug delivery to target tissues.47,48 However, the inherent targeting ability resulting from the physicochemical properties of NPs is not enough to target specific tissues or damaged tissues, and additional studies on additional ligands that can bind to surface receptors on target cells or tissues have been performed to improve the targeting ability of NPs.49 Likewise, nanoencapsulation with cell membranes with targeting molecules and encapsulation of the core NPs with cell membranes confer the targeting ability of the source cell to the NPs.50,51 Thus, MSC mimicking nanoencapsulation can mimic the superior targeting ability of MSCs and confer the advantages of each core NP. In addition, MSC mimicking nanoencapsulations have improved circulation time and camouflaging from phagocytes.52

This review discusses the mechanism of MSC migration to inflammatory sites, addresses the potential strategy for improving the tropism of MSCs using genetic engineering, and discusses the promising therapeutic agent, MSC mimicking nanoencapsulations.

The MSC migration mechanism can be exploited for diverse clinical applications.53 The MSC migration mechanism can be divided into five stages: rolling by selectin, activation of MSCs by chemokines, stopping cell rolling by integrin, transcellular migration, and migration to the damaged site (Figure 1).54,55 Chemokines are secreted naturally by various cells such as tumor cells, stromal cells, and inflammatory cells, maintaining high chemokine concentrations in target cells at the target tissue and inducing signal cascades.5658 Likewise, MSCs express a variety of chemokine receptors, allowing them to migrate and be used as new targeting vectors.5961 MSC migration accelerates depending on the concentration of chemokines, which are the most important factors in the stem cell homing mechanism.62,63 Chemokines consist of various cytokine subfamilies that are closely associated with the migration of immune cells. Chemokines are divided into four classes based on the locations of the two cysteine (C) residues: CC-chemokines, CXC-chemokine, C-chemokine, and CX3 Chemokine.64,65 Each chemokine binds to various MSC receptors and the binding induces a chemokine signaling cascade (Table 1).56,66

Table 1 Chemokine and Chemokine Receptors for Different Chemokine Families

Figure 1 Representation of stem cell homing mechanism.

The mechanisms underlying MSC and leukocyte migration are similar in terms of their migratory dynamics.55 P-selectin glycoprotein ligand-1 (PSGL-1) and E-selectin ligand-1 (ESL-1) are major proteins involved in leukocyte migration that interact with P-selectin and E-selectin present in vascular endothelial cells. However, these promoters are not present in MSCs (Figure 2).53,67

Figure 2 Differences in adhesion protein molecules between leukocytes and mesenchymal stem cells during rolling stages and rolling arrest stage of MSC. (A) The rolling stage of leukocytes starts with adhesion to endothelium with ESL-1 and PSGL-1 on leukocytes. (B) The rolling stage of MSC starts with the adhesion to endothelium with Galectin-1 and CD24 on MSC, and the rolling arrest stage was caused by chemokines that were encountered in the rolling stage and VLA-4 with a high affinity for VACM present in endothelial cells.

Abbreviations: ESL-1, E-selectin ligand-1; PSGL-1, P-selectin glycoprotein ligand-1 VLA-4, very late antigen-4; VCAM, vascular cell adhesion molecule-1.

The initial rolling is facilitated by selectins expressed on the surface of endothelial cells. Various glycoproteins on the surface of MSCs can bind to the selectins and continue the rolling process.68 However, the mechanism of binding of the glycoprotein on MSCs to the selectins is still unclear.69,70 P-selectins and E-selectins, major cell-cell adhesion molecules expressed by endothelial cells, adhere to migrated cells adjacent to endothelial cells and can trigger the rolling process.71 For leukocyte migration, P-selectin glycoprotein ligand-1 (PSGL-1) and E-selectin ligand-1 (ESL-1) expressed on the membranes of leukocytes interact with P-selectins and E-selectins on the endothelial cells, initiating the process.72,73 As already mentioned, MSCs express neither PSGL-1 nor ESL-1. Instead, they express galectin-1 and CD24 on their surfaces, and these bind to E-selectin or P-selectin (Figure 2).7476

In the migratory activation step, MSC receptors are activated in response to inflammatory cytokines, including CXCL12, CXCL8, CXCL4, CCL2, and CCL7.77 The corresponding activation of chemokine receptors of MSCs in response to inflammatory cytokines results in an accumulation of MSCs.58,78 For example, inflamed tissues release inflammatory cytokines,79 and specifically, fibroblasts release CXCL12, which further induces the accumulation of MSCs through ligandreceptor interaction after exposure to hypoxia and cytokine-rich environments in the rat model of inflammation.7982 Previous studies have reported that overexpressing CXCR4, which is a receptor to recognize CXCL12, in MSCs improves the homing ability of MSCs toward inflamed sites.83,84 In short, cytokines are significantly involved in the homing mechanism of MSCs.53

The rolling arrest stage is facilitated by integrin 41 (VLA-4) on MSC.85 VLA-4 is expressed by MSCs which are first activated by CXCL-12 and TNF- chemokines, and activated VLA-4 binds to VCAM-1 expressed on endothelial cells to stop the rotational movement (Figure 2).86,87

Karp et al categorized the migration of MSCs as either systemic homing or non-systemic homing. Systemic homing refers to the process of migration through blood vessels and then across the vascular endothelium near the inflamed site.67,88 The process of migration after passing through the vessels or local injection is called non-systemic homing. In non-systemic migration, stem cells migrate through a chemokine concentration gradient (Figure 3).89 MSCs secrete matrix metalloproteinases (MMPs) during migration. The mechanism underlying MSC migration is currently undefined but MSC migration can be advanced by remodeling the matrix through the secretion of various enzymes.9093 The migration of MSCs to the damaged area is induced by chemokines released from the injured site, such as IL-8, TNF-, insulin-like growth factor (IGF-1), and platelet-derived growth factors (PDGF).9496 MSCs migrate toward the damaged area following a chemokine concentration gradient.87

Figure 3 Differences between systemic and non-systemic homing mechanisms. Both systemic and non-systemic homing to the extracellular matrix and stem cells to their destination, MSCs secrete MMPs and remodel the extracellular matrix.

Abbreviation: MMP, matrix metalloproteinase.

RA is a chronic inflammatory autoimmune disease characterized by distinct painful stiff joints and movement disorders.97 RA affects approximately 1% of the worlds population.98 RA is primarily induced by macrophages, which are involved in the innate immune response and are also involved in adaptive immune responses, together with B cells and T cells.99 Inflammatory diseases are caused by high levels of inflammatory cytokines and a hypoxic low-pH environment in the joints.100,101 Fibroblast-like synoviocytes (FLSs) and accumulated macrophages and neutrophils in the synovium of inflamed joints also express various chemokines.102,103 Chemokines from inflammatory reactions can induce migration of white blood cells and stem cells, which are involved in angiogenesis around joints.101,104,105 More than 50 chemokines are present in the rheumatoid synovial membrane (Table 2). Of the chemokines in the synovium, CXCL12, MIP1-a, CXCL8, and PDGF are the main ones that attract MSCs.106 In the RA environment, CXCL12, a ligand for CXCR4 on MSCs, had 10.71 times higher levels of chemokines than in the normal synovial cell environment. MIP-1a, a chemokine that gathers inflammatory cells, is a ligand for CCR1, which is normally expressed on MSC.107,108 CXCL8 is a ligand for CXCR1 and CXCR2 on MSCs and induces the migration of neutrophils and macrophages, leading to ROS in synovial cells.59 PDGF is a regulatory peptide that is upregulated in the synovial tissue of RA patients.109 PDGF induces greater MSC migration than CXCL12.110 Importantly, stem cells not only have the homing ability to inflamed joints but also have potential as cell therapy with the anti-apoptotic, anti-catabolic, and anti-fibrotic effect of MSC.111 In preclinical trials, MSC treatment has been extensively investigated in collagen-induced arthritis (CIA), a common autoimmune animal model used to study RA. In the RA model, MSCs downregulated inflammatory cytokines such as IFN-, TNF-, IL-4, IL-12, and IL1, and antibodies against collagen, while anti-inflammatory cytokines, such as tumor necrosis factor-inducible gene 6 protein (TSG-6), prostaglandin E2 (PGE2), transforming growth factor-beta (TGF-), IL-10, and IL-6, were upregulated.112116

Table 2 Rheumatoid Arthritis (RA) Chemokines Present in the Pathological Environment and Chemokine Receptors Present in Mesenchymal Stem Cells

Genetic engineering can improve the therapeutic potential of MSCs, including long-term survival, angiogenesis, differentiation into specific lineages, anti- and pro-inflammatory activity, and migratory properties (Figure 4).117,118 Although MSCs already have an intrinsic homing ability, the targeting ability of MSCs and their derivatives, such as membrane vesicles, which are utilized to produce MSC mimicking nanoencapsulation, can be enhanced.118 The therapeutic potential of MSCs can be magnified by reprogramming MSCs via upregulation or downregulation of their native genes, resulting in controlled production of the target protein, or by introducing foreign genes that enable MSCs to express native or non-native products, for example, non-native soluble tumor necrosis factor (TNF) receptor 2 can inhibit TNF-alpha signaling in RA therapies.28

Figure 4 Genetic engineering of mesenchymal stem cells to enhance therapeutic efficacy.

Abbreviations: Sfrp2, secreted frizzled-related protein 2; IGF1, insulin-like growth factor 1; IL-2, interleukin-2; IL-12, interleukin-12; IFN-, interferon-beta; CX3CL1, C-X3-C motif chemokine ligand 1; VEGF, vascular endothelial growth factor; HGF, human growth factor; FGF, fibroblast growth factor; IL-10, interleukin-10; IL-4, interleukin-4; IL18BP, interleukin-18-binding protein; IFN-, interferon-alpha; SDF1, stromal cell-derived factor 1; CXCR4, C-X-C motif chemokine receptor 4; CCR1, C-C motif chemokine receptor 1; BMP2, bone morphogenetic protein 2; mHCN2, mouse hyperpolarization-activated cyclic nucleotide-gated.

MSCs can be genetically engineered using different techniques, including by introducing particular genes into the nucleus of MSCs or editing the genome of MSCs (Figure 5).119 Foreign genes can be transferred into MSCs using liposomes (chemical method), electroporation (physical method), or viral delivery (biological method). Cationic liposomes, also known as lipoplexes, can stably compact negatively charged nucleic acids, leading to the formation of nanomeric vesicular structure.120 Cationic liposomes are commonly produced with a combination of a cationic lipid such as DOTAP, DOTMA, DOGS, DOSPA, and neutral lipids, such as DOPE and cholesterol.121 These liposomes are stable enough to protect their bound nucleic acids from degradation and are competent to enter cells via endocytosis.120 Electroporation briefly creates holes in the cell membrane using an electric field of 1020 kV/cm, and the holes are then rapidly closed by the cells membrane repair mechanism.122 Even though the electric shock induces irreversible cell damage and non-specific transport into the cytoplasm leads to cell death, electroporation ensures successful gene delivery regardless of the target cell or organism. Viral vectors, which are derived from adenovirus, adeno-associated virus (AAV), or lentivirus (LV), have been used to introduce specific genes into MSCs. Recombinant lentiviral vectors are the most widely used systems due to their high tropism to dividing and non-dividing cells, transduction efficiency, and stable expression of transgenes in MSCs, but the random genome integration of transgenes can be an obstacle in clinical applications.123 Adenovirus and AAV systems are appropriate alternative strategies because currently available strains do not have broad genome integration and a strong immune response, unlike LV, thus increasing success and safety in clinical trials.124 As a representative, the Oxford-AstraZeneca COVID-19 vaccine, which has been authorized in 71 countries as a vaccine for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which spread globally and led to the current pandemic, transfers the spike protein gene using an adenovirus-based viral vector.125 Furthermore, there are two AAV-based gene therapies: Luxturna for rare inherited retinal dystrophy and Zolgensma for spinal muscular atrophy.126

Figure 5 Genetic engineering techniques used in the production of bioengineered mesenchymal stem cells.

Clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 were recently used for genome editing and modification because of their simpler design and higher efficiency for genome editing, however, there are safety issues such as off-target effects that induce mutations at sites other than the intended target site.127 The foreign gene is then commonly transferred into non-integrating forms such as plasmid DNA and messenger RNA (mRNA).128

The gene expression machinery can also be manipulated at the cytoplasmic level through RNA interference (RNAi) technology, inhibition of gene expression, or translation using neutralizing targeted mRNA molecules with sequence-specific small RNA molecules such as small interfering RNA (siRNA) or microRNA (miRNA).129 These small RNAs can form enzyme complexes that degrade mRNA molecules and thus decrease their activity by inhibiting translation. Moreover, the pre-transcriptional silencing mechanism of RNAi can induce DNA methylation at genomic positions complementary to siRNA or miRNA with enzyme complexes.

CXC chemokine receptor 4 (CXCR4) is one of the most potent chemokine receptors that is genetically engineered to enhance the migratory properties of MSCs.130 CXCR4 is a chemokine receptor specific for stromal-derived factor-1 (SDF-1), also known as CXC motif chemokine 12 (CXCL12), which is produced by damaged tissues, such as the area of inflammatory bone destruction.131 Several studies on engineering MSCs to increase the expression of the CXCR4 gene have reported a higher density of the CXCR4 receptor on their outer cell membrane and effectively increased the migration of MSCs toward SDF-1.83,132,133 CXC chemokine receptor 7 (CXCR7) also had a high affinity for SDF-1, thus the SDF-1/CXCR7 signaling axis was used to engineer the MSCs.134 CXCR7-overexpressing MSCs in a cerebral ischemia-reperfusion rat hippocampus model promoted migration based on an SDF-1 gradient, cooperating with the SDF-1/CXCR4 signaling axis (Figure 6).37

Figure 6 Engineered mesenchymal stem cells with enhanced migratory abilities.

Abbreviations: CXCR4, C-X-C motif chemokine receptor 4; CXCR7, C-X-C motif chemokine receptor 7; SDF1, stromal cell-derived factor 1; CXCR1, C-X-C motif chemokine receptor 1; IL-8, interleukin-8; Aqp1, aquaporin 1; FAK, focal adhesion kinase.

CXC chemokine receptor 1 (CXCR1) enhances MSC migratory properties.59 CXCR1 is a receptor for IL-8, which is the primary cytokine involved in the recruitment of neutrophils to the site of damage or infection.135 In particular, the IL-8/CXCR1 axis is a key factor for the migration of MSCs toward human glioma cell lines, such as U-87 MG, LN18, U138, and U251, and CXCR1-overexpressing MSCs showed a superior capacity to migrate toward glioma cells and tumors in mice bearing intracranial human gliomas.136

The migratory properties of MSCs were also controlled via aquaporin-1 (Aqp1), which is a water channel molecule that transports water across the cell membrane and regulates endothelial cell migration.137 Aqp1-overexpressing MSCs showed enhanced migration to fracture gap of a rat fracture model with upregulated focal adhesion kinase (FAK) and -catenin, which are important regulators of cell migration.138

Nur77, also known as nerve growth factor IB or NR4A1, and nuclear receptor-related 1 (Nurr1), can play a role in improving the migratory capabilities of MSCs.139,140 The migrating MSCs expressed higher levels of Nur77 and Nurr1 than the non-migrating MSCs, and overexpression of these two nuclear receptors functioning as transcription factors enhanced the migration of MSCs toward SDF-1. The migration of cells is closely related to the cell cycle, and normally, cells in the late S or G2/M phase do not migrate.141 The overexpression of Nur77 and Nurr1 increased the proportion of MSCs in the G0/G1-phase similar to the results of migrating MSCs had more cells in the G1-phase.

MSC mimicking nanoencapsulations are nanoparticles combined with MSC membrane vesicles and these NPs have the greatest advantages as drug delivery systems due to the sustained homing ability of MSCs as well as the advantages of NPs. Particles sized 10150 nm have great advantages in drug delivery systems because they can pass more freely through the cell membrane by the interaction with biomolecules, such as clathrin and caveolin, to facilitate uptake across the cell membrane compared with micron-sized materials.142,143 Various materials have been used to formulate NPs, including silica, polymers, metals, and lipids.144,145 NPs have an inherent ability, called passive targeting, to accumulate at specific sites based on their physicochemical properties such as size, surface charge, surface hydrophilicity, and geometry.146148 However, physicochemical properties are not enough to target specific tissues or damaged tissues, and thus active targeting is a clinically approved strategy involving the addition of ligands that can bind to surface receptors on target cells or tissues.149,150 MSC mimicking nanoencapsulation uses natural or genetically engineered MSC membranes to coat synthetic NPs, producing artificial ectosomes and fusing them with liposomes to increase their targeting ability (Figure 7).151 Especially, MSCs have been studied for targeting inflammation and regenerative drugs, and the mechanism and efficacy of migration toward inflamed tissues have been actively investigated.152 MSC mimicking nanoencapsulation can mimic the well-known migration ability of MSCs and can be equally utilized without safety issues from the direct application of using MSCs. Furthermore, cell membrane encapsulations have a wide range of functions, including prolonged blood circulation time and increased active targeting efficacy from the source cells.153,154 MSC mimicking encapsulations enter recipient cells using multiple pathways.155 MSC mimicking encapsulations can fuse directly with the plasma membrane and can also be taken up through phagocytosis, micropinocytosis, and endocytosis mediated by caveolin or clathrin.156 MSC mimicking encapsulations can be internalized in a highly cell type-specific manner that depends on the recognition of membrane surface molecules by the cell or tissue.157 For example, endothelial colony-forming cell (ECFC)-derived exosomes were shown CXCR4/SDF-1 interaction and enhanced delivery toward the ischemic kidney, and Tspan8-alpha4 complex on lymph node stroma derived extracellular vesicles induced selective uptake by endothelial cells or pancreatic cells with CD54, serving as a major ligand.158,159 Therefore, different source cells may contain protein signals that serve as ligands for other cells, and these receptorligand interactions maximized targeted delivery of NPs.160 This natural mechanism inspired the application of MSC membranes to confer active targeting to NPs.

Figure 7 Mesenchymal stem cell mimicking nanoencapsulation.

Cell membrane-coated NPs (CMCNPs) are biomimetic strategies developed to mimic the properties of cell membranes derived from natural cells such as erythrocytes, white blood cells, cancer cells, stem cells, platelets, or bacterial cells with an NP core.161 Core NPs made of polymer, silica, and metal have been evaluated in attempts to overcome the limitations of conventional drug delivery systems but there are also issues of toxicity and reduced biocompatibility associated with the surface properties of NPs.162,163 Therefore, only a small number of NPs have been approved for medical application by the FDA.164 Coating with cell membrane can enhance the biocompatibility of NPs by improving immune evasion, enhancing circulation time, reducing RES clearance, preventing serum protein adsorption by mimicking cell glycocalyx, which are chemical determinants of self at the surfaces of cells.151,165 Furthermore, the migratory properties of MSCs can also be transferred to NPs by coating them with the cell membrane.45 Coating NPs with MSC membranes not only enhances biocompatibility but also maximizes the therapeutic effect of NPs by mimicking the targeting ability of MSCs.166 Cell membrane-coated NPs are prepared in three steps: extraction of cell membrane vesicles from the source cells, synthesis of the core NPs, and fusion of the membrane vesicles and core NPs to produce cell membrane-coated NPs (Figure 8).167 Cell membrane vesicles, including extracellular vesicles (EVs), can be harvested through cell lysis, mechanical disruption, and centrifugation to isolate, purify the cell membrane vesicles, and remove intracellular components.168 All the processes must be conducted under cold conditions, with protease inhibitors to minimize the denaturation of integral membrane proteins. Cell lysis, which is classically performed using mechanical lysis, including homogenization, sonication, or extrusion followed by differential velocity centrifugation, is necessary to remove intracellular components. Cytochalasin B (CB), a drug that affects cytoskeletonmembrane interactions, induces secretion of membrane vesicles from source cells and has been used to extract the cell membrane.169 The membrane functions of the source cells are preserved in CB-induced vesicles, forming biologically active surface receptors and ion pumps.170 Furthermore, CB-induced vesicles can encapsulate drugs and NPs successfully, and the vesicles can be harvested by centrifugation without a purification step to remove nuclei and cytoplasm.171 Clinically translatable membrane vesicles require scalable production of high volumes of homogeneous vesicles within a short period. Although mechanical methods (eg, shear stress, ultrasonication, or extrusion) are utilized, CB-induced vesicles have shown potential for generating membrane encapsulation for nano-vectors.168 The advantages of CB-induced vesicles versus other methods are compared in Table 3.

Table 3 Comparison of Membrane Vesicle Production Methods

Figure 8 MSC membrane-coated nanoparticles.

Abbreviations: EVs, extracellular vesicles; NPs, nanoparticles.

After extracting cell membrane vesicles, synthesized core NPs are coated with cell membranes, including surface proteins.172 Polymer NPs and inorganic NPs are adopted as materials for the core NPs of CMCNPs, and generally, polylactic-co-glycolic acid (PLGA), polylactic acid (PLA), chitosan, and gelatin are used. PLGA has been approved by FDA is the most common polymer of NPs.173 Biodegradable polymer NPs have gained considerable attention in nanomedicine due to their biocompatibility, nontoxic properties, and the ability to modify their surface as a drug carrier.174 Inorganic NPs are composed of gold, iron, copper, and silicon, which have hydrophilic, biocompatible, and highly stable properties compared with organic materials.175 Furthermore, some photosensitive inorganic NPs have the potential for use in photothermal therapy (PTT) and photodynamic therapy (PDT).176 The fusion of cell membrane vesicles and core NPs is primarily achieved via extrusion or sonication.165 Cell membrane coating of NPs using mechanical extrusion is based on a different-sized porous membrane where core NPs and vesicles are forced to generate vesicle-particle fusion.177 Ultrasonic waves are applied to induce the fusion of vesicles and NPs. However, ultrasonic frequencies need to be optimized to improve fusion efficiency and minimize drug loss and protein degradation.178

CMCNPs have extensively employed to target and treat cancer using the membranes obtained from red blood cell (RBC), platelet and cancer cell.165 In addition, membrane from MSC also utilized to target tumor and ischemia with various types of core NPs, such as MSC membrane coated PLGA NPs targeting liver tumors, MSC membrane coated gelatin nanogels targeting HeLa cell, MSC membrane coated silica NPs targeting HeLa cell, MSC membrane coated PLGA NPs targeting hindlimb ischemia, and MSC membrane coated iron oxide NPs for targeting the ischemic brain.179183 However, there are few studies on CMCNPs using stem cells for the treatment of arthritis. Increased targeting ability to arthritis was introduced using MSC-derived EVs and NPs.184,185 MSC membrane-coated NPs are proming strategy for clearing raised concerns from direct use of MSC (with or without NPs) in terms of toxicity, reduced biocompatibility, and poor targeting ability of NPs for the treatment of arthritis.

Exosomes are natural NPs that range in size from 40 nm to 120 nm and are derived from the multivesicular body (MVB), which is an endosome defined by intraluminal vesicles (ILVs) that bud inward into the endosomal lumen, fuse with the cell surface, and are then released as exosomes.186 Because of their ability to express receptors on their surfaces, MSC-derived exosomes are also considered potential candidates for targeting.187 Exosomes are commonly referred to as intracellular communication molecules that transfer various compounds through physiological mechanisms such as immune response, neural communication, and antigen presentation in diseases such as cancer, cardiovascular disease, diabetes, and inflammation.188

However, there are several limitations to the application of exosomes as targeted therapeutic carriers. First, the limited reproducibility of exosomes is a major challenge. In this field, the standardized techniques for isolation and purification of exosomes are lacking, and conventional methods containing multi-step ultracentrifugation often lead to contamination of other types of EVs. Furthermore, exosomes extracted from cell cultures can vary and display inconsistent properties even when the same type of donor cells were used.189 Second, precise characterization studies of exosomes are needed. Unknown properties of exosomes can hinder therapeutic efficiencies, for example, when using exosomes as cancer therapeutics, the use of cancer cell-derived exosomes should be avoided because cancer cell-derived exosomes may contain oncogenic factors that may contribute to cancer progression.190 Finally, cost-effective methods for the large-scale production of exosomes are needed for clinical application. The yield of exosomes is much lower than EVs. Depending on the exosome secretion capacity of donor cells, the yield of exosomes is restricted, and large-scale cell culture technology for the production of exosomes is high difficulty and costly and isolation of exosomes is the time-consuming and low-efficient method.156

Ectosome is an EV generated by outward budding from the plasma membrane followed by pinching off and release to the extracellular parts. Recently, artificially produced ectosome utilized as an alternative to exosomes in targeted therapeutics due to stable productivity regardless of cell type compared with conventional exosome. Artificial ectosomes, containing modified cargo and targeting molecules have recently been introduced for specific purposes (Figure 9).191,192 Artificial ectosomes are typically prepared by breaking bigger cells or cell membrane fractions into smaller ectosomes, similar size to natural exosomes, containing modified cargo such as RNA molecules, which control specific genes, and chemical drugs such as anticancer drugs.193 Naturally secreted exosomes in conditioned media from modified source cells can be harvested by differential ultracentrifugation, density gradients, precipitation, filtration, and size exclusion chromatography for exosome separation.194 Even though there are several commercial kits for isolating exosomes simply and easily, challenges in compliant scalable production on a large scale, including purity, homogeneity, and reproducibility, have made it difficult to use naturally secreted exosomes in clinical settings.195 Therefore, artificially produced ectosomes are appropriate for use in clinical applications, with novel production methods that can meet clinical production criteria. Production of artificially produced ectosomes begins by breaking the cell membrane fraction of cultured cells and then using them to produce cell membrane vesicles to form ectosomes. As mentioned above, cell membrane vesicles are extracted from source cells in several ways, and cell membrane vesicles are extracted through polycarbonate membrane filters to reduce the mean size to a size similar to that of natural exosomes.196 Furthermore, specific microfluidic devices mounted on microblades (fabricated in silicon nitride) enable direct slicing of living cells as they flow through the hydrophilic microchannels of the device.197 The sliced cell fraction reassembles and forms ectosomes. There are several strategies for loading exogenous therapeutic cargos such as drugs, DNA, RNA, lipids, metabolites, and proteins, into exosomes or artificial ectosomes in vitro: electroporation, incubation for passive loading of cargo or active loading with membrane permeabilizer, freeze and thaw cycles, sonication, and extrusion.198 In addition, protein or RNA molecules can be loaded by co-expressing them in source cells via bio-engineering, and proteins designed to interact with the protein inside the cell membrane can be loaded actively into exosomes or artificial ectosomes.157 Targeting molecules at the surface of exosomes or artificial ectosomes can also be engineered in a manner similar to the genetic engineering of MSCs.

Figure 9 Mesenchymal stem cell-derived exosomes and artificial ectosomes. (A) Wound healing effect of MSC-derived exosomes and artificial ectosomes,231 (B) treatment of organ injuries by MSC-derived exosomes and artificial ectosomes,42,232234 (C) anti-cancer activity of MSC-derived exosomes and artificial ectosomes.200,202,235

Most of the exosomes derived from MSCs for drug delivery have employed miRNAs or siRNAs, inhibiting translation of specific mRNA, with anticancer activity, for example, miR-146b, miR-122, and miR-379, which are used for cancer targeting by membrane surface molecules on MSC-derived exosomes.199201 Drugs such as doxorubicin, paclitaxel, and curcumin were also loaded into MSC-derived exosomes to target cancer.202204 However, artificial ectosomes derived from MSCs as arthritis therapeutics remains largely unexplored area, while EVs, mixtures of natural ectosomes and exosomes, derived from MSCs have studied in the treatment of arthritis.184 Artificial ectosomes with intrinsic tropism from MSCs plus additional targeting ability with engineering increase the chances of ectosomes reaching target tissues with ligandreceptor interactions before being taken up by macrophages.205 Eventually, this will decrease off-target binding and side effects, leading to lower therapeutic dosages while maintaining therapeutic efficacy.206,207

Liposomes are spherical vesicles that are artificially synthesized through the hydration of dry phospholipids.208 The clinically available liposome is a lipid bilayer surrounding a hollow core with a diameter of 50150 nm. Therapeutic molecules, such as anticancer drugs (doxorubicin and daunorubicin citrate) or nucleic acids, can be loaded into this hollow core for delivery.209 Due to their amphipathic nature, liposomes can load both hydrophilic (polar) molecules in an aqueous interior and hydrophobic (nonpolar) molecules in the lipid membrane. They are well-established biomedical applications and are the most common nanostructures used in advanced drug delivery.210 Furthermore, liposomes have several advantages, including versatile structure, biocompatibility, low toxicity, non-immunogenicity, biodegradability, and synergy with drugs: targeted drug delivery, reduction of the toxic effect of drugs, protection against drug degradation, and enhanced circulation half-life.211 Moreover, surfaces can be modified by either coating them with a functionalized polymer or PEG chains to improve targeted delivery and increase their circulation time in biological systems.212 Liposomes have been investigated for use in a wide variety of therapeutic applications, including cancer diagnostics and therapy, vaccines, brain-targeted drug delivery, and anti-microbial therapy. A new approach was recently proposed for providing targeting features to liposomes by fusing them with cell membrane vesicles, generating molecules called membrane-fused liposomes (Figure 10).213 Cell membrane vesicles retain the surface membrane molecules from source cells, which are responsible for efficient tissue targeting and cellular uptake by target cells.214 However, the immunogenicity of cell membrane vesicles leads to their rapid clearance by macrophages in the body and their low drug loading efficiencies present challenges for their use as drug delivery systems.156 However, membrane-fused liposomes have advantages of stability, long half-life in circulation, and low immunogenicity due to the liposome, and the targeting feature of cell membrane vesicles is completely transferred to the liposome.215 Furthermore, the encapsulation efficiencies of doxorubicin were similar when liposomes and membrane-fused liposomes were used, indicating that the relatively high drug encapsulation capacity of liposomes was maintained during the fusion process.216 Combining membrane-fused liposomes with macrophage-derived membrane vesicles showed differential targeting and cytotoxicity against normal and cancerous cells.217 Although only a few studies have been conducted, these results corroborate that membrane-fused liposomes are a potentially promising future drug delivery system with increased targeting ability. MSCs show intrinsic tropism toward arthritis, and further engineering and modification to enhance their targeting ability make them attractive candidates for the development of drug delivery systems. Fusing MSC exosomes with liposomes, taking advantage of both membrane vesicles and liposomes, is a promising technique for future drug delivery systems.

Figure 10 Mesenchymal stem cell membrane-fused liposomes.

MSCs have great potential as targeted therapies due to their greater ability to home to targeted pathophysiological sites. The intrinsic ability to home to wounds or to the tumor microenvironment secreting inflammatory mediators make MSCs and their derivatives targeting strategies for cancer and inflammatory disease.218,219 Contrary to the well-known homing mechanisms of various blood cells, it is still not clear how homing occurs in MSCs. So far, the mechanism of MSC tethering, which connects long, thin cell membrane cylinders called tethers to the adherent area for migration, has not been clarified. Recent studies have shown that galectin-1, VCAM-1, and ICAM are associated with MSC tethering,53,220 but more research is needed to accurately elucidate the tethering mechanism of MSCs. MSC chemotaxis is well defined and there is strong evidence relating it to the homing ability of MSCs.53 Chemotaxis involves recognizing chemokines through chemokine receptors on MSCs and migrating to chemokines in a gradient-dependent manner.221 RA, a representative inflammatory disease, is associated with well-profiled chemokines such as CXCR1, CXCR4, and CXCR7, which are recognized by chemokine receptors on MSCs. In addition, damaged joints in RA continuously secrete cytokines until they are treated, giving MSCs an advantage as future therapeutic agents for RA.222 However, there are several obstacles to utilizing MSCs as RA therapeutics. In clinical settings, the functional capability of MSCs is significantly affected by the health status of the donor patient.223 MSC yield is significantly reduced in patients undergoing steroid-based treatment and the quality of MSCs is dependent on the donors age and environment.35 In addition, when MSCs are used clinically, cryopreservation and defrosting are necessary, but these procedures shorten the life span of MSCs.224 Therefore, NPs mimicking MSCs are an alternative strategy for overcoming the limitations of MSCs. Additionally, further engineering and modification of MSCs can enhance the therapeutic effect by changing the targeting molecules and loaded drugs. In particular, upregulation of receptors associated with chemotaxis through genetic engineering can confer the additional ability of MSCs to home to specific sites, while the increase in engraftment maximizes the therapeutic effect of MSCs.36,225

Furthermore, there are several methods that can be used to exploit the targeting ability of MSCs as drug delivery systems. MSCs mimicking nanoencapsulation, which consists of MSC membrane-coated NPs, MSC-derived artificial ectosomes, and MSC membrane-fused liposomes, can mimic the targeting ability of MSCs while retaining the advantages of NPs. MSC-membrane-coated NPs are synthesized using inorganic or polymer NPs and membranes from MSCs to coat inner nanosized structures. Because they mimic the biological characteristics of MSC membranes, MSC-membrane-coated NPs can not only escape from immune surveillance but also effectively improve targeting ability, with combined functions of the unique properties of core NPs and MSC membranes.226 Exosomes are also an appropriate candidate for use in MSC membranes, utilizing these targeting abilities. However, natural exosomes lack reproducibility and stable productivity, thus artificial ectosomes with targeting ability produced via synthetic routes can increase the local concentration of ectosomes at the targeted site, thereby reducing toxicity and side effects and maximizing therapeutic efficacy.156 MSC membrane-fused liposomes, a novel system, can also transfer the targeting molecules on the surface of MSCs to liposomes; thus, the advantages of liposomes are retained, but with targeting ability. With advancements in nanotechnology of drug delivery systems, the research in cell-mimicking nanoencapsulation will be very useful. Efficient drug delivery systems fundamentally improve the quality of life of patients with a low dose of medication, low side effects, and subsequent treatment of diseases.227 However, research on cell-mimicking nanoencapsulation is at an early stage, and several problems need to be addressed. To predict the nanotoxicity of artificially synthesized MSC mimicking nanoencapsulations, interactions between lipids and drugs, drug release mechanisms near the targeted site, in vivo compatibility, and immunological physiological studies must be conducted before clinical application.

This work was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF-2019M3A9H1103690), by the Gachon University Gil Medical Center (FRD2021-03), and by the Gachon University research fund of 2020 (GGU-202008430004).

The authors report no conflicts of interest in this work.

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Stem Cell Mimicking Nanoencapsulation for Targeting Arthrit | IJN - Dove Medical Press

1Regenerative Medicine Centre, Arabian Gulf University, Manama, Bahrain; 2Department of Molecular Medicine, College of Medicine and Medical Sciences, Arabian Gulf University, Manama, Bahrain

Introduction: Stroke is a leading cause of death and disability worldwide. The disease is caused by reduced blood flow into the brain resulting in the sudden death of neurons. Limited spontaneous recovery might occur after stroke or brain injury, stem cell-based therapies have been used to promote these processes as there are no drugs currently on the market to promote brain recovery or neurogenesis. Adult stem cells (ASCs) have shown the ability of differentiation and regeneration and are well studied in literature. ASCs have also demonstrated safety in clinical application and, therefore, are currently being investigated as a promising alternative intervention for the treatment of stroke.Methods: Eleven studies have been systematically selected and reviewed to determine if autologous adult stem cells are effective in the treatment of stroke. Collectively, 368 patients were enrolled across the 11 trials, out of which 195 received stem cell transplantation and 173 served as control. Using data collected from the clinical outcomes, a broad comparison and a meta-analysis were conducted by comparing studies that followed a similar study design.Results: Improvement in patients clinical outcomes was observed. However, the overall results showed no clinical significance in patients transplanted with stem cells than the control population.Conclusion: Most of the trials were early phase studies that focused on safety rather than efficacy. Stem cells have demonstrated breakthrough results in the field of regenerative medicine. Therefore, study design could be improved in the future by enrolling a larger patient population and focusing more on localized delivery rather than intravenous transplantation. Trials should also introduce a more standardized method of analyzing and reporting clinical outcomes to achieve a better comparable outcome and possibly recognize the full potential that these cells have to offer.

Keywords: adult stem cells, autologous, neurogenesis, inflammation, clinical application, stroke, stroke recovery, systematic review, meta-analysis

Stroke is the second leading cause of death worldwide and one of the leading causes of disability.1 The blockade or the rupture of a blood vessel to the brain leads to either ischemic or hemorrhagic stroke, respectively.2,3 The extent and the location of the damaged brain tissue may be associated with irreversible cognitive impairment or decline in speech, comprehension, memory, and partial or total physical paralysis.4

Four chronological phases, namely hyperacute, acute, subacute, and chronic, describe the strokes cellular manifestations.5 The hyperacute phase is immediate and associated with glutamate-mediated excitotoxicity and a progressive neuronal death that can last a few hours.6 The glutamate, a potent excitatory neurotransmitter, is also an inducer of neurodegeneration following stroke.7 The acute phase, which could last over a week after the stroke, is associated with the delayed and progressive neuronal death and the infiltration of immune cells.5 The following subacute phase can extend up to three months after the stroke and is mainly associated with reduced inflammation and increased plasticity of neurons, astrocytes, microglia, and endothelial cells, allowing spontaneous recovery.8 In the chronic phase that follows, the plasticity of cells is reduced and only permits rehabilitation-induced recovery.5

The immediate treatments differ for ischemic and hemorrhagic strokes. Immediate intervention is required to restore the blood flow to the brain following an ischemic stroke. Thrombolytic agents, such as activase (Alteplase), a recombinant tissue plasminogen activator (tPA), are commonly given intravenously to dissolve the blood clots. Other more invasive approaches, such as a thrombectomy, use stents or catheters to remove the blood clot.9 Antiplatelet agents like Aspirin, anticoagulants, blood pressure medicines, or statins are generally given to reduce the risk of recurrence. Some ischemic strokes are caused by the narrowing of the carotid artery due to the accumulation of fatty plaques; a carotid endarterectomy is performed to correct the constriction.

The treatment of a hemorrhagic stroke requires a different approach. An emergency craniotomy is usually performed to remove the blood accumulating in the brain and repair the damaged blood vessels. Accumulation of cerebrospinal fluid in brain ventricles (hydrocephalus) is also a frequent complication following a hemorrhagic stroke, which requires surgery to drain the fluid. Medications to lower blood pressure are given before surgery and to prevent further seizures.10

These immediate treatments are critical to minimize the long-term consequence of the stroke but do not address the post-stroke symptoms caused by neurodegeneration. New therapeutic approaches adapted to the physiology of each phase of the stroke are currently developed. A promising therapy has been the use of stem cells.11 In this review, different clinical trials involving the use of various stem cells for the treatment of stroke are presented and compared using a meta-analysis of the published results.

To narrow down the relevant literature, a search strategy focused on original literature and reporting the clinical application of stem cells in stroke was established. An NCBI PubMed word search for stroke, stem cells, and adult stem cells yielded 146 clinical studies between 2010 and 2021. Finally, 11 studies, using autologous adult stem cells in the treatment of stroke, were considered. A PRISMA flow diagram detailing an overview of the study selection procedure and the inclusion and exclusion of papers is included in Appendix I. The inclusion criteria comprise the injection of autologous adult stem cells at any stroke stages (hyperacute, acute, sub-acute, chronic), and clinical trials whose results have been published in the last 11 years. The exclusion criteria include studies published more than 11 years ago, studies not published in English, all preclinical studies, other diseases related to stroke (ex. cardiovascular diseases), embryonic or induced pluripotent stem cells, allogeneic stem cells, and other cell therapies. Two independent researchers reviewed and filtered the 146 studies by reading the titles and abstracts. All three authors approved the final selected studies.

Stem cells are undifferentiated and unspecialized cells characterized by their ability to self-renew and their potential to differentiate into specialized cell types.12 Ischemic stroke causes severe damage to the brain cells by destroying the heterogeneous cell population and neuronal connections along with vascular systems. The regenerative potential of several types of stem cells like embryonic stem cells, neural stem cells, adult stem cells (mesenchymal stem cells), and induced pluripotent stem cells have been assessed for treating stroke.

Adult stem cells exhibit multipotency and the ability to self-renew and differentiate into specialized cell types. They have been widely used in clinical trials and a safe option thus far in treating various diseases.12,13,14 The plasticity of these cells allow their differentiation across tissue lineages when exposed to defined cell culture conditions.15 There are multiple easily accessible sources of adult stem cells, mainly the bone marrow, blood, and adipose tissue. In clinical settings, both autologous and HLA-matched allogeneic cells have been transplanted and are deemed to be safe.

Adult stem cells can secrete a variety of bioactive substances into the injured brain following a stroke in the form of paracrine signals.1618 The paracrine signals include growth factors, trophic factors, and extracellular vesicles, which may be associated with enhanced neurogenesis, angiogenesis, and synaptogenesis (Figure 1). Also, mesenchymal stem cells (MSCs) are thought to contribute to the resolution of the stroke by attenuating inflammation,19 reducing scar thickness, enhancing autophagy, normalizing microenvironmental and metabolic profiles and possibly replacing damaged cells.20

Figure 1 Schematic depicting the clinical application of different cells in stroke patients. The cells were delivered in one of three ways, intravenously, intra-arterially, or via stereotactic injections. Once administered, the cells play a role in providing paracrine signals and growth factors to facilitate angiogenesis and cell regeneration, immunomodulatory effects that serve to protect the neurons from further damage caused by inflammation, and finally, trans-differentiation of stem cells. Data from Dabrowska S, Andrzejewska A, Lukomska B, Janowski M.19 Created with BioRender.com.

A few routes of administration have been used to deliver the stem cells to the patients. The most common is through intravenous injection. Intra-arterial delivery is also performed; but this mode can be extremely painful to patients compared to an intravenous transfusion. The third approach is via stereotactic injections. This is an invasive surgery that involves injecting the cells directly into the site of affected in the brain.

Also known as mesenchymal stromal cells or medicinal signaling cells, MSCs can be derived from different sources including bone marrow, peripheral blood, lungs, heart, skeletal muscle, adipose tissue, dental pulp, dermis, umbilical cord, placenta, amniotic fluid membrane and many more.21 MSCs are characterized by positive cell surface markers, including Stro-1, CD19, CD44, CD90, CD105, CD106, CD146, and CD166. The cells are also CD14, CD34, and CD45 negative.22,23 The cells are thought to provide a niche to stem cells in normal tissue and releases paracrine factors that promote neurogenesis (Figure 2).19,20,24 During the acute and subacute stage of stroke, MSCs may inhibit inflammation, thus, reducing the incidence of debilitating damage and symptoms that may occur post-stroke.

Figure 2 Schematic describing the role of mesenchymal stem cells in stroke. The cells release different growth factors, signals, and cytokines that serve to facilitate various functions. Through the release of cytokines, they can modulate inflammation and block apoptosis. The growth factors aid in promoting angiogenesis and neurogenesis. Data from Maleki M, Ghanbarvand F, Behvarz MR, Ejtemaei M, Ghadirkhomi E.23 Created with BioRender.com.

Derived from the bone marrow, mononuclear cells contain several types of stem cells, including mesenchymal stem cells and hematopoietic progenitor cells that give rise to hematopoietic stem cells and various other differentiated cells. They can produce and secrete multiple growth factors and cytokines. They are also attracted to the lesion or damage site where they can accelerate angiogenesis and promote repair endogenously through the proliferation of the hosts neural stem cells. Mononuclear cells have also demonstrated the ability to decrease neurodegeneration, modulate inflammation, and prevent apoptosis in animal models.25,26

Blood stem cells are a small number of bone marrow stem cells that have been mobilized into the blood by hematopoietic growth factors, which regulate the differentiation and proliferation of cells. They are increasingly used in cell therapies, most recently for the regeneration of non-hematopoietic tissue, including neurons. Recombinant human granulocyte colony-stimulating factor (G-CSF) has been used as a stimulator of hematopoiesis, which in turn amplifies the yield of peripheral blood stem cells.27

The literature review considered 11 clinical trials that satisfied the inclusion criteria. A total of 368 patients were enrolled including 179 patients treated with various types of adult stem cells. The clinical trial number 7 contained a historical control of 59 patients included in the data analysis (Figure 3). The analysis was done on the published clinical and functional outcomes of various tests such as mRS, and mBI. The analysis compared the patients clinical outcomes post stem cell therapy to the baseline clinical results. The variance in the patient population should be noted.

Figure 3 Schematic representing an overview of the total number of patients enrolled in all 11 clinical trials and the number of patients administered with each type of adult stem cell.

Abbreviations: MSC, mesenchymal stem cells; PBSC, peripheral blood stem cells; MNC, mononuclear stem cells; ADSVF, adipose derived stromal vascular fraction; ALD401, aldehyde dehydrogenase-bright stem cells.

Meta-analyses were conducted using modified Rankin scale (mRS) and Barthel Index (BI) scores. In the clinical trials, mRS and BI scores are commonly used scales to assess functional outcome in stroke patients. The BI score was developed to measures the patients performance in 10 activities of daily life from self-care to mobility. An mRS score follows a similar outcome but measures the patients independence in daily tasks rather than performance. OpenMeta[Analyst], an open-source meta-analysis software, was used to produce random-effects meta-analyses and create the forest plots. The number of patients, mean, and standard deviation (SD) of the scores were calculated to determine the study weights and create the forest plots.

All 11 clinical trials were compared based on their clinical and functional outcomes (Table 1; Figure 4). The data shows that stem cell therapy is relatively safe and viable in the treatment of stroke, indicating an improvement in patients overall health. However, when compared to the control, the improvement is not significant as patients in the control group also exhibited an improved clinical and functional outcome. Across trials that assigned a control group, the patients either received a placebo, or alternative form of treatment including physiotherapy. Variance in functional and clinical tests used to assess patients, and the number of patients enrolled in each trial results in a discrepancy in reporting. Most of the trials failed to report whether the patients suffered from an acute, subacute or chronic stroke which also affects the results of the treatments, with acute and subacute being the optimal periods to receive treatment due to cell plasticity and inhibiting unwarranted inflammation.39 The deaths in both the treatment and control population were attributed to the progression of the disease and are likely not the result of the treatment. Albeit, it has been noted down as they had occurred during the follow-up period.

Table 1 Overview of Selected Clinical Trials

Figure 4 Overview of clinical outcomes of the 11 clinical trials (N=368). (A) The chart shows the percentages of patients who have either improved, remained stable, deteriorated, or deceased. Some clinical trials are without a control arm. (B) The plot shows the overall percentage of patients that have improved after receiving either the stem cell treatment versus the standard of care. (C) The plot shows the overall percentage of patients that have remained stable and showed no clinical or functional improvement in the follow up period. (D) The plot shows the overall percentage of the patients whose condition has deteriorated in the follow up period.

A meta-analysis was conducted using modified Rankin scale (mRS) and Barthel Index (BI) scores. The results of the mRS scores were analyzed (Figure 5A; Table 2). In terms of study weights, CT6 is the highest (40.07%) as shown in Table 2. The combined results of the mRS functional test from CT1, CT5, CT6, and CT11 show a non-significant statistical heterogeneity in the studies (p-value 0.113). In conjunction, BI scores were analyzed and a meta-analysis was conducted using four comparable trials (Figure 5B; Table 3). In terms of study weights, CT3 is the highest (32.384%) as shown in Table 3. The combined results of BI scores from CT5, CT3, CT10, and CT11 show a statistical heterogeneity in the results of the studies (p-value 0.004) thus, precision of results is uncertain. More comparable studies are needed to have a better outcome. Therefore, standardized testing in trails should be considered in future trials.

Table 2 Clinical Outcomes of mRS Test

Table 3 Clinical Outcomes of BI Test

Figure 5 Meta-analysis conducted using three comparable trials. (A) Meta-analysis conducted using four comparable trials (CT1, CT5, CT6, CT11) for the mRS test. (B) Meta-analysis conducted using four comparable trials (CT3, CT5, CT10, and CT11) for the BI test.

Across all trials, patients injected with the MSCs, and other cell types did not trigger a degradation of the patient conditions demonstrating the safety of the procedures. However, the efficacy of the use of adult stem cells is less clear when compared to patients in the control group. This discrepancy could, however, exhibit improvement in patients receiving the treatment compared to the baseline clinical outcomes. However, when therapy results are compared to the patients in the control population that either received a placebo, physiotherapy, or prescribed medication, the efficacy of the use of adult stem cells is less clear.

Although multiple adult stem cell types have been used, mesenchymal stem cells have been widely used in many clinical trials. Albeit there is a consensus that the therapeutic and clinical outcomes of mesenchymal stem cell treatments are not yet significantly effective compared to the control treatment. Some trials have shown patient improvements, such as CT6 and CT8, where the investigators used PBSCs or BMMNSC, respectively. Although subjectively, the cells appear to be therapeutic, objectively, there are many limitations to the study designs included in this review. Not all the trials enrolled a control arm for a better comparison as some were only testing safety rather than efficacy. Therefore, we cannot conclude whether autologous adult stem cells are an effective therapeutic stroke treatment. Only autologous cells were included in this review as they are non-immunogenic.

Another factor to consider is the evident discrepancy in the number of patients enrolled in each trial. The trials included in this review are in Phase I and II trials, which primarily focus on safety rather than efficacy. Intravenous injection was the most used method of cell delivery due to its convenience and safety. However, it is commonly considered that this approach is not the most effective way of delivery, as the majority of the transplanted cells get absorbed by non-targeted organs, and the remaining cells find difficulty passing the blood-brain barrier. Due to this dilemma, the most obvious approach would be to inject the cells directly into the brain. However, a stereotactic procedure is invasive and will require general anesthesia, which may compromise patients health, especially ones suffering from acute ischemic stroke.40 Thus, an intra-arterial delivery seems feasible to accomplish the task as it is less invasive and might be more effective than an intravenous treatment such as the cases observed in CT3 and CT8. In CT11, the patients demonstrated a visible fmRI recovery as well as recovery of motor function in patients that have received a stem cell treatment. However, the analysis and test scores show no significance between the treatment group and the control group.

Only a few studies were comparable using a similar evaluation approach. Considering these factors, better study designs enrolling a higher number of patients in randomized clinical trial against the standard of care are needed. Moreover, a better grouping of the patients based on the type and stage of stroke may provide more relevant information for the safety and efficacy of adult stem cells for the recovery and prevention of recurrence of stroke patients.

ADSVF, Adipose-derived stromal vascular fraction; ASCs, Adult stem cells; ALD-401, Aldehyde dehydrogenase 401; BI, Barthel Index; BM-MNC, Bone marrow-derived mononuclear cells; FLAIR, Fluid attenuated inversion recovery; fMRI, Functional magnetic resonance imaging; G-CSF, Granulocyte colony-stimulating factor; MRI, Magnetic resonance imaging; MSCs, Mesenchymal stem cells; mRS, modified Rankin Scale; NIHSS, National Institute of Health Stroke Scale; PBSC, Peripheral blood stem cells; SD, Standard deviation; tPA, tissue plasminogen activator.

All authors made a significant contribution to the work reported, whether that is in the conception, study design, execution, acquisition of data, analysis and interpretation, or in all these areas; took part in drafting, revising or critically reviewing the article; gave final approval of the version to be published; have agreed on the journal to which the article has been submitted; and agree to be accountable for all aspects of the work.

There is no funding to report.

We declare there is no conflict of interest.

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Autologous Adult Stem Cells in the Treatment of Stroke | SCCAA - Dove Medical Press

Dr Pradeep Mahajan, Regenerative Medicine Researcher, StemRx Bioscience Solutions highlights the importance and other aspects of stem cell technology

Globally, we are seeing a change in the type of age-specific, chronic, debilitating diseases. Thus, the manner in which we diagnose and treat such diseases is also seeing a paradigm shift. From empirical use of drugs to target-specific treatments, we are now advancing towards molecular dysfunction-based therapies.

I have been in the field of clinical medicine and surgery for over 3 decades now and I have always been fascinated by new research. Among the substantial advances in the healthcare field, I believe regenerative medicine and cell-based therapy have been game changers. We saw hematopoietic stem cells being used to treat blood cancers and related diseases for over 3-4 decades. Now we are seeing an expansion in the applications of stem cells in treating various acute, chronic, lifestyle, and even genetic and congenital diseases. The need arose because conventional medicine is gradually losing potency in treating diseases and patients are often left at the mercy of nature to take its course.

With increasing knowledge of stem cells, the trend to utilise the endogenous repair mechanisms of the human body gained popularity. Cells, growth factors and other biological products, when present at the right site; at the right moment, stimulate the natural healing mechanisms of the body and aid in management of health conditions. Cell-based therapy thus marked the beginning of a new era in regenerative medicine.

Stem cells are present in several tissues, namely, embryo, umbilical cord, placenta, as well as adult body tissues. These are the master cells of the body that have roles in development of the body, repairing and regenerating injured tissues (at a cellular level), and maintaining homeostasis even in an healthy individual. Of course, we have all heard of ethical issues regarding the use of embryonic stem cells as well as their tumor-forming issue. Regarding umbilical cord stem cells, the trend of banking this tissue has just begun; therefore, the majority of us would not have the umbilical cord as a source of stem cells. Keeping in mind these aspects, researchers started focusing on adult stem cells that can be derived from different tissues of the human body. The common sources are bone marrow, fat tissue, peripheral blood, and teeth, among others. The chief advantage is that, the source being autologous, the therapy is safe and is not associated with side effects.

Coming to the diseases that can be treated using stem cellswe have just scratched the tip of the iceberg. There are several health conditions that plague mankindarthritis, diabetes, nerve-related conditions, traumatic injuries, etc. Conventionally, one would be prescribed medications (often for prolong periods or even for their lifetime) or be advised surgery. Nonetheless, in several cases, the quality of life of a patient is compromised. The various properties of stem cells help reduce swelling in the body, regulate the immune system, enhance the functioning of other cells, and create a healthy environment for health cells to thrive. Through this, one can target a myriad of pathologies at the molecular level, in a minimally/non-invasive manner.

Patients today are quite aware of the benefits of regenerative medicine and cell based therapy, but there is still a long distance to cover. Countries are promoting research and development in the field of regenerative medicine and cell-based therapy. Research advances pertaining to introducing products with cell and scaffold based technology through tissue engineering are underway. Bioactive scaffolds that are capable of supporting activation and differentiation of host stem cells at the required site are being developed. In the future, it will be possible to use human native sites as micro-niche/micro-environment for potentiation of the human bodys site-specific response. Another breakthrough in the field of cell-based therapy is immunotherapy that aims to utilise certain parts of a persons immune system and stimulate them to fight diseases such as cancer.

The scope of cell-based therapy is endless. All we need is more research, awareness, and implementation to permit reach of the treatment to every stratum of the society. Soon, we will talk about treating diseases with cells and not pills and knives!

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Importance of stem cells-Past, present and future - Express Healthcare

Advance Market Analytics published a new research publication on Stem Cells Market Insights, to 2026 with 232 pages and enriched with self-explained Tables and charts in presentable format. In the Study you will find new evolving Trends, Drivers, Restraints, Opportunities generated by targeting market associated stakeholders. The growth of the Stem Cells Market was mainly driven by the increasing R&D spending across the world.

Some of the key players profiled in the study are:

Smith & Nephew (United Kingdom),Celgene Corporation (United States),BIOTIME, INC. (United States),Cynata (Australia),Applied Cell Technology (Hungary),STEMCELL Technologies Inc. (Canada),BioTime Inc. (United States),Cytori Therapeutics, Inc. (United States),Astellas Pharma Inc. (Japan),U.S. Stem Cell, Inc. (United States),Takara Holdings. (Japan)

Get Free Exclusive PDF Sample Copy of This Research @ https://www.advancemarketanalytics.com/sample-report/72815-global-stem-cells-market-1

Scope of the Report of Stem Cells

The stem cell is used for treating chronic diseases such as cardiovascular disorders, cancer, diabetes, and others. Growing research and development in stem cell isolation techniques propelling market growth. For instance, a surgeon from Turkey developed a method for obtaining stem cells from the human body without enzymes which are generally used for the isolation of stem cells. Further, growing healthcare infrastructure in the developing economies and government spending on the life science research and development expected to drive the demand for stem cell market over the forecasted period.

Market Trend:

Emphasizing On Development of Regenerative Medicine

Technological Advancement in Stem Cell Harvesting and Isolation Techniques

Market Drivers:

Rising Prevalence of Chronic Diseases such as Cardiovascular Disorders, Cancer, and others

Growing Healthcare Infrastructure in the Developing Economies

Challenges:

Lack of Awareness Regarding Stem Cell Therapy in the Low and Middle Income Group Countries

Opportunities:

Growing Demand for Cellular Therapies

Rising Application of Autologous Therapy

The titled segments and sub-section of the market are illuminated below:by Type (Adult Stem Cells (Neuronal, Hematopoietic, Mesenchymal, Umbilical Cord, Others), Human Embryonic Stem Cells (hESC), Induced Pluripotent Stem Cells, Very Small Embryonic-Like Stem Cells), Application (Regenerative Medicine (Neurology, Orthopedics, Oncology, Hematology, Cardiovascular and Myocardial Infraction, Injuries, Diabetes, Liver Disorder, Incontinence, Others), Drug Discovery and Development), Technology (Cell Acquisition (Bone Marrow Harvest, Umbilical Blood Cord, Apheresis), Cell Production (Therapeutic Cloning, In-vitro Fertilization, Cell Culture, Isolation), Cryopreservation, Expansion and Sub-Culture), Therapy (Autologous, Allogeneic)

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Region Included are: North America, Europe, Asia Pacific, Oceania, South America, Middle East & Africa

Country Level Break-Up: United States, Canada, Mexico, Brazil, Argentina, Colombia, Chile, South Africa, Nigeria, Tunisia, Morocco, Germany, United Kingdom (UK), the Netherlands, Spain, Italy, Belgium, Austria, Turkey, Russia, France, Poland, Israel, United Arab Emirates, Qatar, Saudi Arabia, China, Japan, Taiwan, South Korea, Singapore, India, Australia and New Zealand etc.

Strategic Points Covered in Table of Content of Global Stem Cells Market:

Chapter 1: Introduction, market driving force product Objective of Study and Research Scope the Stem Cells market

Chapter 2: Exclusive Summary the basic information of the Stem Cells Market.

Chapter 3: Displaying the Market Dynamics- Drivers, Trends and Challenges of the Stem Cells

Chapter 4: Presenting the Stem Cells Market Factor Analysis Porters Five Forces, Supply/Value Chain, PESTEL analysis, Market Entropy, Patent/Trademark Analysis.

Chapter 5: Displaying market size by Type, End User and Region 2015-2020

Chapter 6: Evaluating the leading manufacturers of the Stem Cells market which consists of its Competitive Landscape, Peer Group Analysis, BCG Matrix & Company Profile

Chapter 7: To evaluate the market by segments, by countries and by manufacturers with revenue share and sales by key countries (2021-2026).

Chapter 8 & 9: Displaying the Appendix, Methodology and Data Source

Finally, Stem Cells Market is a valuable source of guidance for individuals and companies in decision framework.

Read Detailed Index of full Research Study at @ https://www.advancemarketanalytics.com/reports/72815-global-stem-cells-market-1

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Stem Cells Market to Witness Gigantic Growth by 2026 LSMedia - LSMedia

PALM BEACH, Fla., Dec. 21, 2021 /PRNewswire/ -- FinancialNewsMedia.com News Commentary - Systemic mastocytosis is rare disease which affects very few people and it causes due to C-kit mutation which leads to higher number of mast cell production in the body resulting in accumulation of excessive mast cells in the internal body organs such as spleen, liver, bone marrow and small intestine etc. Recently, the World Health Organization (WHO) updated the prognosis, diagnosis and systemic mastocytosis treatment guidelines for the disease which in turn helped to bring uniformity in the approach by healthcare professionals. The manufacturers in the systemic mastocytosis treatment market are focusing on evaluating possible treatment options to cure the disease by investing heavily in the research & development. Various leading manufacturers are focusing on gaining FDA approval to respective drugs for the systemic mastocytosis treatment to enhance their revenue generation. A reportfrom Future Market Insights said:"Increasing awareness about the systemic mastocytosis treatment as well as symptoms of the disease due to extended effort by non-profit organizations, governmental associations and through other platforms expected to drive the growth of the systemic mastocytosis treatment market Increasing approvals and launches of drugs for the systemic mastocytosis treatment expected to drive the growth of the market Increasing spending on research & development by various pharmaceutical companies to develop novel systemic mastocytosis treatment expected to further fuel the growth of market. Increasing early diagnosis rate subsequently followed by increasing treatment seeking rate further expected to drive the growth of the systemic mastocytosis treatment market." Active companies in the markets today include: Hoth Therapeutics, Inc. (NASDAQ:HOTH), Longeveron Inc. (NASDAQ: LGVN), Bristol Myers Squibb (NYSE: BMY), Takeda Pharmaceutical Company Limited (NYSE: TAK), Amgen (NASDAQ: AMGN).

Future Market Insights continued:"The global systemic mastocytosis treatment market is expected to experience significant growth due to increasing novel treatment options. By drug class, systemic mastocytosis treatment market is expected to be dominated by the mast cell stabilizers due to superior efficacy. By indication, systemic mastocytosis treatment market is expected to be dominated by indolent systemic mastocytosis (ISM) due to higher prevalence. By route o administration, systemic mastocytosis treatment market is expected to be dominated by injectables. By distribution channel, systemic mastocytosis treatment market is expected to be dominated by the retail pharmacies due to higher patient footfall. The global systemic mastocytosis treatment market is expected to be dominated by the North America due to comparatively higher prevalence of the disease. Europe systemic mastocytosis treatment market is expected to be second most lucrative market due to higher treatment seeking rate. Latin America expected to show gradual growth in the systemic mastocytosis treatment market due to steadily increasing diagnosis. Asia-Pacific is emerging systemic mastocytosis treatment market due to increasing diagnosis subsequently followed by treatment. Middle East & Africa is the least lucrative systemic mastocytosis treatment market due to least diagnostic rate and lower awareness about the symptoms."

Hoth Therapeutics, Inc. (NASDAQ:HOTH) BREAKING NEWS: Hoth Therapeutics Announces Submission of Orphan Designation Application for HT-KIT to Treat Mastocytosis Hoth Therapeutics, Inc., a patient-focusedclinical-stage biopharmaceutical company, announced it submitted an Orphan Drug Designation Application to the US Food and Drug Administration (FDA) for HT-KIT for the treatment of mastocyctosis. HT-KIT is an antisense oligonucleotide that targets the proto-oncogene cKIT by inducing mRNA frame shifting, resulting in apoptosis of neoplastic mast cells. The KIT signaling pathway is implicated in multiple diseases, including all types of mastocytosis (such as aggressive systemic mastocytosis (ASM), mast cell leukemia (MCL), and systemic mastocytosis with associated hematological neoplasm (SM-AHN)), acute myeloid leukemia, gastrointestinal stromal tumors, and anaphylaxis.

Drugs intended to treat orphan diseases (rare diseases that affect less than 200,000 people in the US)are eligible to apply for Orphan Drug Designation (ODD), which provides multiple benefits to the sponsor during development and after approval. Hoth intends to pursue these benefits as part of the drug development for HT-KIT for treatment of mastocytosis, pending designation of the ODD application.

Benefits of Orphan Drug Designation - Under the Orphan Drug Act, drug companies can apply for ODD, and if granted, the drug will have a status which gives companies exclusive marketing and development rights along with other benefits to recover the costs of researching and developing the drug. A tax credit of 50% of the qualified clinical drug testing costs awarded upon drug approval is also possible. Regulatory streamlining and provide special assistance to companies that develop drugs for rare patient populations. In addition to exclusive rights and cost benefits, the FDA will provide protocol assistance, potential decreased wait-time for drug approval, discounts on registration fees, and eligibility for market exclusivity after approval.

Key benefits of ODD:

Hoth recently announcedthat its novelanti-cancer therapeuticexhibited highly positive results in humanized mast cell neoplasm models, representative in vitro and in vivo models for aggressive, mast cell-derived cancers such as mast cell leukemia and mast cell sarcoma. CONTINUED Read the Hoth Therapeutics full press release by going to: https://ir.hoththerapeutics.com/news-releases

In other news and developments of note in the markets this week:

Amgen (NASDAQ: AMGN) recently announced that the U.S. Food and Drug Administration (FDA) has approved Amgen and AstraZeneca'sTezspire (tezepelumab-ekko) for the add-on maintenance treatment of adult and pediatric patients aged 12 years and older with severe asthma.

Tezspirewas approved following a Priority Review by the FDA and based on results from the PATHFINDER clinical trial program. The application included results from the pivotal NAVIGATOR Phase 3 trial in whichTezspiredemonstrated superiority across every primary and key secondary endpoint in patients with severe asthma, compared to placebo, when added to standard therapy.

Longeveron Inc. (NASDAQ: LGVN), a clinical stage biotechnology company developing cellular therapies for chronic aging-related and certain life-threatening conditions, recently announced that the U.S. Food and Drug Administration (FDA) has granted Orphan Drug Designation (ODD) for Lomecel-B for the treatment of Hypoplastic Left Heart Syndrome (HLHS), a rare and life-threatening congenital heart defect in infants.

ODD is intended to assist and encourage companies to develop safe and effective therapies for the treatment of rare diseases or conditions. ODD positions Longeveron to be able to potentially leverage a range of financial and regulatory benefits, including government grants for conducting clinical trials, waiver of FDA user fees for the potential submission of a marketing application, and certain tax credits. Receiving ODD may also result in the product receiving seven years market exclusivity upon approval for use in the rare disease or condition for which the product was designated if all of the statutory and regulatory requirements are met.

Bristol Myers Squibb (NYSE: BMY) recently announced thatOrencia(abatacept) was approved by the U.S. Food and Drug Administration (FDA) for the prophylaxis, or prevention, of acute graft versus host disease (aGvHD), in combination with a calcineurin inhibitor (CNI) and methotrexate (MTX), in adults and pediatric patients 2 years of age and older undergoing hematopoietic stem cell transplantation (HSCT) from a matched or 1 allele-mismatched unrelated donor (URD).

"Orenciais the first FDA-approved therapy to prevent acute graft versus host disease following hematopoietic stem cell transplant, a potentially life-threatening complication that can pose a comparatively higher risk to racial and ethnic minority populations in the U.S. due to difficulty finding appropriately matched donors," said Tina Deignan, senior vice president, U.S. Immunology, Bristol Myers Squibb. "With this fourth indication forOrencia,Bristol Myers Squibb draws on its legacy and expertise in both immunology and hematology to deliver an important treatment option for patients in a disease with high unmet need.

Takeda Pharmaceutical Company Limited (NYSE: TAK) announced that the Committee for Medicinal Products for Human Use (CHMP) of the European Medicines Agency (EMA) has recommended the approval of intravenous (IV) vedolizumab for the treatment of adult patients with moderately to severely active chronic pouchitis, who have undergone proctocolectomy and ileal pouch-anal anastomosis (IPAA) for ulcerative colitis (UC), and have had an inadequate response with or lost response to antibiotic therapy. The CHMP opinion will now be reviewed by the European Commission. If approved, vedolizumab will become the first treatment indicated for active chronic pouchitis across the European Union.

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Systemic Mastocytosis Treatments Gain Hope Due To Increasing Novel Treatment Options - PRNewswire

Int J Cell Biol. 2016; 2016: 6940283.

Department of Biological Sciences, Indian Institute of Science Education and Research (IISER), Bhopal, Madhya Pradesh 462066, India

Department of Biological Sciences, Indian Institute of Science Education and Research (IISER), Bhopal, Madhya Pradesh 462066, India

Academic Editor: Paul J. Higgins

Received 2016 Mar 13; Accepted 2016 Jun 5.

This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Regenerative medicine, the most recent and emerging branch of medical science, deals with functional restoration of tissues or organs for the patient suffering from severe injuries or chronic disease. The spectacular progress in the field of stem cell research has laid the foundation for cell based therapies of disease which cannot be cured by conventional medicines. The indefinite self-renewal and potential to differentiate into other types of cells represent stem cells as frontiers of regenerative medicine. The transdifferentiating potential of stem cells varies with source and according to that regenerative applications also change. Advancements in gene editing and tissue engineering technology have endorsed the ex vivo remodelling of stem cells grown into 3D organoids and tissue structures for personalized applications. This review outlines the most recent advancement in transplantation and tissue engineering technologies of ESCs, TSPSCs, MSCs, UCSCs, BMSCs, and iPSCs in regenerative medicine. Additionally, this review also discusses stem cells regenerative application in wildlife conservation.

Regenerative medicine, the most recent and emerging branch of medical science, deals with functional restoration of specific tissue and/or organ of the patients suffering with severe injuries or chronic disease conditions, in the state where bodies own regenerative responses do not suffice [1]. In the present scenario donated tissues and organs cannot meet the transplantation demands of aged and diseased populations that have driven the thrust for search for the alternatives. Stem cells are endorsed with indefinite cell division potential, can transdifferentiate into other types of cells, and have emerged as frontline regenerative medicine source in recent time, for reparation of tissues and organs anomalies occurring due to congenital defects, disease, and age associated effects [1]. Stem cells pave foundation for all tissue and organ system of the body and mediates diverse role in disease progression, development, and tissue repair processes in host. On the basis of transdifferentiation potential, stem cells are of four types, that is, (1) unipotent, (2) multipotent, (3) pluripotent, and (4) totipotent [2]. Zygote, the only totipotent stem cell in human body, can give rise to whole organism through the process of transdifferentiation, while cells from inner cells mass (ICM) of embryo are pluripotent in their nature and can differentiate into cells representing three germ layers but do not differentiate into cells of extraembryonic tissue [2]. Stemness and transdifferentiation potential of the embryonic, extraembryonic, fetal, or adult stem cells depend on functional status of pluripotency factors like OCT4, cMYC, KLF44, NANOG, SOX2, and so forth [35]. Ectopic expression or functional restoration of endogenous pluripotency factors epigenetically transforms terminally differentiated cells into ESCs-like cells [3], known as induced pluripotent stem cells (iPSCs) [3, 4]. On the basis of regenerative applications, stem cells can be categorized as embryonic stem cells (ESCs), tissue specific progenitor stem cells (TSPSCs), mesenchymal stem cells (MSCs), umbilical cord stem cells (UCSCs), bone marrow stem cells (BMSCs), and iPSCs (; ). The transplantation of stem cells can be autologous, allogenic, and syngeneic for induction of tissue regeneration and immunolysis of pathogen or malignant cells. For avoiding the consequences of host-versus-graft rejections, tissue typing of human leucocyte antigens (HLA) for tissue and organ transplant as well as use of immune suppressant is recommended [6]. Stem cells express major histocompatibility complex (MHC) receptor in low and secret chemokine that recruitment of endothelial and immune cells is enabling tissue tolerance at graft site [6]. The current stem cell regenerative medicine approaches are founded onto tissue engineering technologies that combine the principles of cell transplantation, material science, and microengineering for development of organoid; those can be used for physiological restoration of damaged tissue and organs. The tissue engineering technology generates nascent tissue on biodegradable 3D-scaffolds [7, 8]. The ideal scaffolds support cell adhesion and ingrowths, mimic mechanics of target tissue, support angiogenesis and neovascularisation for appropriate tissue perfusion, and, being nonimmunogenic to host, do not require systemic immune suppressant [9]. Stem cells number in tissue transplant impacts upon regenerative outcome [10]; in that case prior ex vivo expansion of transplantable stem cells is required [11]. For successful regenerative outcomes, transplanted stem cells must survive, proliferate, and differentiate in site specific manner and integrate into host circulatory system [12]. This review provides framework of most recent (; Figures ) advancement in transplantation and tissue engineering technologies of ESCs, TSPSCs, MSCs, UCSCs, BMSCs, and iPSCs in regenerative medicine. Additionally, this review also discusses stem cells as the tool of regenerative applications in wildlife conservation.

Promises of stem cells in regenerative medicine: the six classes of stem cells, that is, embryonic stem cells (ESCs), tissue specific progenitor stem cells (TSPSCs), mesenchymal stem cells (MSCs), umbilical cord stem cells (UCSCs), bone marrow stem cells (BMSCs), and induced pluripotent stem cells (iPSCs), have many promises in regenerative medicine and disease therapeutics.

ESCs in regenerative medicine: ESCs, sourced from ICM of gastrula, have tremendous promises in regenerative medicine. These cells can differentiate into more than 200 types of cells representing three germ layers. With defined culture conditions, ESCs can be transformed into hepatocytes, retinal ganglion cells, chondrocytes, pancreatic progenitor cells, cone cells, cardiomyocytes, pacemaker cells, eggs, and sperms which can be used in regeneration of tissue and treatment of disease in tissue specific manner.

TSPSCs in regenerative medicine: tissue specific stem and progenitor cells have potential to differentiate into other cells of the tissue. Characteristically inner ear stem cells can be transformed into auditory hair cells, skin progenitors into vascular smooth muscle cells, mesoangioblasts into tibialis anterior muscles, and dental pulp stem cells into serotonin cells. The 3D-culture of TSPSCs in complex biomaterial gives rise to tissue organoids, such as pancreatic organoid from pancreatic progenitor, intestinal tissue organoids from intestinal progenitor cells, and fallopian tube organoids from fallopian tube epithelial cells. Transplantation of TSPSCs regenerates targets tissue such as regeneration of tibialis muscles from mesoangioblasts, cardiac tissue from AdSCs, and corneal tissue from limbal stem cells. Cell growth and transformation factors secreted by TSPSCs can change cells fate to become other types of cell, such that SSCs coculture with skin, prostate, and intestine mesenchyme transforms these cells from MSCs into epithelial cells fate.

MSCs in regenerative medicine: mesenchymal stem cells are CD73+, CD90+, CD105+, CD34, CD45, CD11b, CD14, CD19, and CD79a cells, also known as stromal cells. These bodily MSCs represented here do not account for MSCs of bone marrow and umbilical cord. Upon transplantation and transdifferentiation these bodily MSCs regenerate into cartilage, bones, and muscles tissue. Heart scar formed after heart attack and liver cirrhosis can be treated from MSCs. ECM coating provides the niche environment for MSCs to regenerate into hair follicle, stimulating hair growth.

UCSCs in regenerative medicine: umbilical cord, the readily available source of stem cells, has emerged as futuristic source for personalized stem cell therapy. Transplantation of UCSCs to Krabbe's disease patients regenerates myelin tissue and recovers neuroblastoma patients through restoring tissue homeostasis. The UCSCs organoids are readily available tissue source for treatment of neurodegenerative disease. Peritoneal fibrosis caused by long term dialysis, tendon tissue degeneration, and defective hyaline cartilage can be regenerated by UCSCs. Intravenous injection of UCSCs enables treatment of diabetes, spinal myelitis, systemic lupus erythematosus, Hodgkin's lymphoma, and congenital neuropathies. Cord blood stem cells banking avails long lasting source of stem cells for personalized therapy and regenerative medicine.

BMSCs in regenerative medicine: bone marrow, the soft sponge bone tissue that consisted of stromal, hematopoietic, and mesenchymal and progenitor stem cells, is responsible for blood formation. Even halo-HLA matched BMSCs can cure from disease and regenerate tissue. BMSCs can regenerate craniofacial tissue, brain tissue, diaphragm tissue, and liver tissue and restore erectile function and transdifferentiation monocytes. These multipotent stem cells can cure host from cancer and infection of HIV and HCV.

iPSCs in regenerative medicine: using the edge of iPSCs technology, skin fibroblasts and other adult tissues derived, terminally differentiated cells can be transformed into ESCs-like cells. It is possible that adult cells can be transformed into cells of distinct lineages bypassing the phase of pluripotency. The tissue specific defined culture can transform skin cells to become trophoblast, heart valve cells, photoreceptor cells, immune cells, melanocytes, and so forth. ECM complexation with iPSCs enables generation of tissue organoids for lung, kidney, brain, and other organs of the body. Similar to ESCs, iPSCs also can be transformed into cells representing three germ layers such as pacemaker cells and serotonin cells.

Stem cells in wildlife conservation: tissue biopsies obtained from dead and live wild animals can be either cryopreserved or transdifferentiated to other types of cells, through culture in defined culture medium or in vivo maturation. Stem cells and adult tissue derived iPSCs have great potential of regenerative medicine and disease therapeutics. Gonadal tissue procured from dead wild animals can be matured, ex vivo and in vivo for generation of sperm and egg, which can be used for assistive reproductive technology oriented captive breeding of wild animals or even for resurrection of wildlife.

Application of stem cells in regenerative medicine: stem cells (ESCs, TSPSCs, MSCs, UCSCs, BMSCs, and iPSCs) have diverse applications in tissue regeneration and disease therapeutics.

For the first time in 1998, Thomson isolated human ESCs (hESCs) [13]. ESCs are pluripotent in their nature and can give rise to more than 200 types of cells and promises for the treatment of any kinds of disease [13]. The pluripotency fate of ESCs is governed by functional dynamics of transcription factors OCT4, SOX2, NANOG, and so forth, which are termed as pluripotency factors. The two alleles of the OCT4 are held apart in pluripotency state in ESCs; phase through homologues pairing during embryogenesis and transdifferentiation processes [14] has been considered as critical regulatory switch for lineage commitment of ESCs. The diverse lineage commitment potential represents ESCs as ideal model for regenerative therapeutics of disease and tissue anomalies. This section of review on ESCs discusses transplantation and transdifferentiation of ESCs into retinal ganglion, hepatocytes, cardiomyocytes, pancreatic progenitors, chondrocytes, cones, egg sperm, and pacemaker cells (; ). Infection, cancer treatment, and accidents can cause spinal cord injuries (SCIs). The transplantation of hESCs to paraplegic or quadriplegic SCI patients improves body control, balance, sensation, and limbal movements [15], where transplanted stem cells do homing to injury sites. By birth, humans have fixed numbers of cone cells; degeneration of retinal pigment epithelium (RPE) of macula in central retina causes age-related macular degeneration (ARMD). The genomic incorporation of COCO gene (expressed during embryogenesis) in the developing embryo leads lineage commitment of ESCs into cone cells, through suppression of TGF, BMP, and Wnt signalling pathways. Transplantation of these cone cells to eye recovers individual from ARMD phenomenon, where transplanted cone cells migrate and form sheet-like structure in host retina [16]. However, establishment of missing neuronal connection of retinal ganglion cells (RGCs), cones, and PRE is the most challenging aspect of ARMD therapeutics. Recently, Donald Z Jacks group at John Hopkins University School of Medicine has generated RGCs from CRISPER-Cas9-m-Cherry reporter ESCs [17]. During ESCs transdifferentiation process, CRIPER-Cas9 directs the knock-in of m-Cherry reporter into 3UTR of BRN3B gene, which is specifically expressed in RGCs and can be used for purification of generated RGCs from other cells [17]. Furthermore, incorporation of forskolin in transdifferentiation regime boosts generation of RGCs. Coaxing of these RGCs into biomaterial scaffolds directs axonal differentiation of RGCs. Further modification in RGCs generation regime and composition of biomaterial scaffolds might enable restoration of vision for ARMD and glaucoma patients [17]. Globally, especially in India, cardiovascular problems are a more common cause of human death, where biomedical therapeutics require immediate restoration of heart functions for the very survival of the patient. Regeneration of cardiac tissue can be achieved by transplantation of cardiomyocytes, ESCs-derived cardiovascular progenitors, and bone marrow derived mononuclear cells (BMDMNCs); however healing by cardiomyocytes and progenitor cells is superior to BMDMNCs but mature cardiomyocytes have higher tissue healing potential, suppress heart arrhythmias, couple electromagnetically into hearts functions, and provide mechanical and electrical repair without any associated tumorigenic effects [18, 19]. Like CM differentiation, ESCs derived liver stem cells can be transformed into Cytp450-hepatocytes, mediating chemical modification and catabolism of toxic xenobiotic drugs [20]. Even today, availability and variability of functional hepatocytes are a major a challenge for testing drug toxicity [20]. Stimulation of ESCs and ex vivo VitK12 and lithocholic acid (a by-product of intestinal flora regulating drug metabolism during infancy) activates pregnane X receptor (PXR), CYP3A4, and CYP2C9, which leads to differentiation of ESCs into hepatocytes; those are functionally similar to primary hepatocytes, for their ability to produce albumin and apolipoprotein B100 [20]. These hepatocytes are excellent source for the endpoint screening of drugs for accurate prediction of clinical outcomes [20]. Generation of hepatic cells from ESCs can be achieved in multiple ways, as serum-free differentiation [21], chemical approaches [20, 22], and genetic transformation [23, 24]. These ESCs-derived hepatocytes are long lasting source for treatment of liver injuries and high throughput screening of drugs [20, 23, 24]. Transplantation of the inert biomaterial encapsulated hESCs-derived pancreatic progenitors (CD24+, CD49+, and CD133+) differentiates into -cells, minimizing high fat diet induced glycemic and obesity effects in mice [25] (). Addition of antidiabetic drugs into transdifferentiation regime can boost ESCs conservation into -cells [25], which theoretically can cure T2DM permanently [25]. ESCs can be differentiated directly into insulin secreting -cells (marked with GLUT2, INS1, GCK, and PDX1) which can be achieved through PDX1 mediated epigenetic reprogramming [26]. Globally, osteoarthritis affects millions of people and occurs when cartilage at joints wears away, causing stiffness of the joints. The available therapeutics for arthritis relieve symptoms but do not initiate reverse generation of cartilage. For young individuals and athletes replacement of joints is not feasible like old populations; in that case transplantation of stem cells represents an alternative for healing cartilage injuries [27]. Chondrocytes, the cartilage forming cells derived from hESC, embedded in fibrin gel effectively heal defective cartilage within 12 weeks, when transplanted to focal cartilage defects of knee joints in mice without any negative effect [27]. Transplanted chondrocytes form cell aggregates, positive for SOX9 and collagen II, and defined chondrocytes are active for more than 12wks at transplantation site, advocating clinical suitability of chondrocytes for treatment of cartilage lesions [27]. The integrity of ESCs to integrate and differentiate into electrophysiologically active cells provides a means for natural regulation of heart rhythm as biological pacemaker. Coaxing of ESCs into inert biomaterial as well as propagation in defined culture conditions leads to transdifferentiation of ESCs to become sinoatrial node (SAN) pacemaker cells (PCs) [28]. Genomic incorporation TBox3 into ESCs ex vivo leads to generation of PCs-like cells; those express activated leukocyte cells adhesion molecules (ALCAM) and exhibit similarity to PCs for gene expression and immune functions [28]. Transplantation of PCs can restore pacemaker functions of the ailing heart [28]. In summary, ESCs can be transdifferentiated into any kinds of cells representing three germ layers of the body, being most promising source of regenerative medicine for tissue regeneration and disease therapy (). Ethical concerns limit the applications of ESCs, where set guidelines need to be followed; in that case TSPSCs, MSCs, UCSCs, BMSCs, and iPSCs can be explored as alternatives.

TSPSCs maintain tissue homeostasis through continuous cell division, but, unlike ESCs, TSPSCs retain stem cells plasticity and differentiation in tissue specific manner, giving rise to few types of cells (). The number of TSPSCs population to total cells population is too low; in that case their harvesting as well as in vitro manipulation is really a tricky task [29], to explore them for therapeutic scale. Human body has foundation from various types of TSPSCs; discussing the therapeutic application for all types is not feasible. This section of review discusses therapeutic application of pancreatic progenitor cells (PPCs), dental pulp stem cells (DPSCs), inner ear stem cells (IESCs), intestinal progenitor cells (IPCs), limbal progenitor stem cells (LPSCs), epithelial progenitor stem cells (EPSCs), mesoangioblasts (MABs), spermatogonial stem cells (SSCs), the skin derived precursors (SKPs), and adipose derived stem cells (AdSCs) (; ). During embryogenesis PPCs give rise to insulin-producing -cells. The differentiation of PPCs to become -cells is negatively regulated by insulin [30]. PPCs require active FGF and Notch signalling; growing more rapidly in community than in single cell populations advocates the functional importance of niche effect in self-renewal and transdifferentiation processes. In 3D-scaffold culture system, mice embryo derived PPCs grow into hollow organoid spheres; those finally differentiate into insulin-producing -cell clusters [29]. The DSPSCs, responsible for maintenance of teeth health status, can be sourced from apical papilla, deciduous teeth, dental follicle, and periodontal ligaments, have emerged as regenerative medicine candidate, and might be explored for treatment of various kinds of disease including restoration neurogenic functions in teeth [31, 32]. Expansion of DSPSCs in chemically defined neuronal culture medium transforms them into a mixed population of cholinergic, GABAergic, and glutaminergic neurons; those are known to respond towards acetylcholine, GABA, and glutamine stimulations in vivo. These transformed neuronal cells express nestin, glial fibrillary acidic protein (GFAP), III-tubulin, and voltage gated L-type Ca2+ channels [32]. However, absence of Na+ and K+ channels does not support spontaneous action potential generation, necessary for response generation against environmental stimulus. All together, these primordial neuronal stem cells have possible therapeutic potential for treatment of neurodental problems [32]. Sometimes, brain tumor chemotherapy can cause neurodegeneration mediated cognitive impairment, a condition known as chemobrain [33]. The intrahippocampal transplantation of human derived neuronal stem cells to cyclophosphamide behavioural decremented mice restores cognitive functions in a month time. Here the transplanted stem cells differentiate into neuronal and astroglial lineage, reduce neuroinflammation, and restore microglial functions [33]. Furthermore, transplantation of stem cells, followed by chemotherapy, directs pyramidal and granule-cell neurons of the gyrus and CA1 subfields of hippocampus which leads to reduction in spine and dendritic cell density in the brain. These findings suggest that transplantation of stem cells to cranium restores cognitive functions of the chemobrain [33]. The hair cells of the auditory system produced during development are not postmitotic; loss of hair cells cannot be replaced by inner ear stem cells, due to active state of the Notch signalling [34]. Stimulation of inner ear progenitors with -secretase inhibitor ({"type":"entrez-nucleotide","attrs":{"text":"LY411575","term_id":"1257853995","term_text":"LY411575"}}LY411575) abrogates Notch signalling through activation of transcription factor atonal homologue 1 (Atoh1) and directs transdifferentiation of progenitors into cochlear hair cells [34]. Transplantation of in vitro generated hair cells restores acoustic functions in mice, which can be the potential regenerative medicine candidates for the treatment of deafness [34]. Generation of the hair cells also can be achieved through overexpression of -catenin and Atoh1 in Lrg5+ cells in vivo [35]. Similar to ear progenitors, intestine of the digestive tract also has its own tissue specific progenitor stem cells, mediating regeneration of the intestinal tissue [34, 36]. Dysregulation of the common stem cells signalling pathways, Notch/BMP/TGF-/Wnt, in the intestinal tissue leads to disease. Information on these signalling pathways [37] is critically important in designing therapeutics. Coaxing of the intestinal tissue specific progenitors with immune cells (macrophages), connective tissue cells (myofibroblasts), and probiotic bacteria into 3D-scaffolds of inert biomaterial, crafting biological environment, is suitable for differentiation of progenitors to occupy the crypt-villi structures into these scaffolds [36]. Omental implementation of these crypt-villi structures to dogs enhances intestinal mucosa through regeneration of goblet cells containing intestinal tissue [36]. These intestinal scaffolds are close approach for generation of implantable intestinal tissue, divested by infection, trauma, cancer, necrotizing enterocolitis (NEC), and so forth [36]. In vitro culture conditions cause differentiation of intestinal stem cells to become other types of cells, whereas incorporation of valproic acid and CHIR-99021 in culture conditions avoids differentiation of intestinal stem cells, enabling generation of indefinite pool of stem cells to be used for regenerative applications [38]. The limbal stem cells of the basal limbal epithelium, marked with ABCB5, are essential for regeneration and maintenance of corneal tissue [39]. Functional status of ABCB5 is critical for survival and functional integrity of limbal stem cells, protecting them from apoptotic cell death [39]. Limbal stem cells deficiency leads to replacement of corneal epithelium with visually dead conjunctival tissue, which can be contributed by burns, inflammation, and genetic factors [40]. Transplanted human cornea stem cells to mice regrown into fully functional human cornea, possibly supported by blood eye barrier phenomena, can be used for treatment of eye diseases, where regeneration of corneal tissue is critically required for vision restoration [39]. Muscle degenerative disease like duchenne muscular dystrophy (DMD) can cause extensive thrashing of muscle tissue, where tissue engineering technology can be deployed for functional restoration of tissue through regeneration [41]. Encapsulation of mouse or human derived MABs (engineered to express placental derived growth factor (PDGF)) into polyethylene glycol (PEG) fibrinogen hydrogel and their transplantation beneath the skin at ablated tibialis anterior form artificial muscles, which are functionally similar to those of normal tibialis anterior muscles [41]. The PDGF attracts various cell types of vasculogenic and neurogenic potential to the site of transplantation, supporting transdifferentiation of mesoangioblasts to become muscle fibrils [41]. The therapeutic application of MABs in skeletal muscle regeneration and other therapeutic outcomes has been reviewed by others [42]. One of the most important tissue specific stem cells, the male germline stem cells or spermatogonial stem cells (SSCs), produces spermatogenic lineage through mesenchymal and epithets cells [43] which itself creates niche effect on other cells. In vivo transplantation of SSCs with prostate, skin, and uterine mesenchyme leads to differentiation of these cells to become epithelia of the tissue of origin [43]. These newly formed tissues exhibit all physical and physiological characteristics of prostate and skin and the physical characteristics of prostate, skin, and uterus, express tissue specific markers, and suggest that factors secreted from SSCs lead to lineage conservation which defines the importance of niche effect in regenerative medicine [43]. According to an estimate, more than 100 million people are suffering from the condition of diabetic retinopathy, a progressive dropout of vascularisation in retina that leads to loss of vision [44]. The intravitreal injection of adipose derived stem cells (AdSCs) to the eye restores microvascular capillary bed in mice. The AdSCs from healthy donor produce higher amounts of vasoprotective factors compared to glycemic mice, enabling superior vascularisation [44]. However use of AdSCs for disease therapeutics needs further standardization for cell counts in dose of transplant and monitoring of therapeutic outcomes at population scale [44]. Apart from AdSCs, other kinds of stem cells also have therapeutic potential in regenerative medicine for treatment of eye defects, which has been reviewed by others [45]. Fallopian tubes, connecting ovaries to uterus, are the sites where fertilization of the egg takes place. Infection in fallopian tubes can lead to inflammation, tissue scarring, and closure of the fallopian tube which often leads to infertility and ectopic pregnancies. Fallopian is also the site where onset of ovarian cancer takes place. The studies on origin and etiology of ovarian cancer are restricted due to lack of technical advancement for culture of epithelial cells. The in vitro 3D organoid culture of clinically obtained fallopian tube epithelial cells retains their tissue specificity, keeps cells alive, which differentiate into typical ciliated and secretory cells of fallopian tube, and advocates that ectopic examination of fallopian tube in organoid culture settings might be the ideal approach for screening of cancer [46]. The sustained growth and differentiation of fallopian TSPSCs into fallopian tube organoid depend both on the active state of the Wnt and on paracrine Notch signalling [46]. Similar to fallopian tube stem cells, subcutaneous visceral tissue specific cardiac adipose (CA) derived stem cells (AdSCs) have the potential of differentiation into cardiovascular tissue [47]. Systemic infusion of CA-AdSCs into ischemic myocardium of mice regenerates heart tissue and improves cardiac function through differentiation to endothelial cells, vascular smooth cells, and cardiomyocytes and vascular smooth cells. The differentiation and heart regeneration potential of CA-AdSCs are higher than AdSCs [48], representing CA-AdSCs as potent regenerative medicine candidates for myocardial ischemic therapy [47]. The skin derived precursors (SKPs), the progenitors of dermal papilla/hair/hair sheath, give rise to multiple tissues of mesodermal and/or ectodermal origin such as neurons, Schwann cells, adipocytes, chondrocytes, and vascular smooth muscle cells (VSMCs). VSMCs mediate wound healing and angiogenesis process can be derived from human foreskin progenitor SKPs, suggesting that SKPs derived VSMCs are potential regenerative medicine candidates for wound healing and vasculature injuries treatments [49]. In summary, TSPSCs are potentiated with tissue regeneration, where advancement in organoid culture (; ) technologies defines the importance of niche effect in tissue regeneration and therapeutic outcomes of ex vivo expanded stem cells.

MSCs, the multilineage stem cells, differentiate only to tissue of mesodermal origin, which includes tendons, bone, cartilage, ligaments, muscles, and neurons [50]. MSCs are the cells which express combination of markers: CD73+, CD90+, CD105+, CD11b, CD14, CD19, CD34, CD45, CD79a, and HLA-DR, reviewed elsewhere [50]. The application of MSCs in regenerative medicine can be generalized from ongoing clinical trials, phasing through different state of completions, reviewed elsewhere [90]. This section of review outlines the most recent representative applications of MSCs (; ). The anatomical and physiological characteristics of both donor and receiver have equal impact on therapeutic outcomes. The bone marrow derived MSCs (BMDMSCs) from baboon are morphologically and phenotypically similar to those of bladder stem cells and can be used in regeneration of bladder tissue. The BMDMSCs (CD105+, CD73+, CD34, and CD45), expressing GFP reporter, coaxed with small intestinal submucosa (SIS) scaffolds, augment healing of degenerated bladder tissue within 10wks of the transplantation [51]. The combinatorial CD characterized MACs are functionally active at transplantation site, which suggests that CD characterization of donor MSCs yields superior regenerative outcomes [51]. MSCs also have potential to regenerate liver tissue and treat liver cirrhosis, reviewed elsewhere [91]. The regenerative medicinal application of MSCs utilizes cells in two formats as direct transplantation or first transdifferentiation and then transplantation; ex vivo transdifferentiation of MSCs deploys retroviral delivery system that can cause oncogenic effect on cells. Nonviral, NanoScript technology, comprising utility of transcription factors (TFs) functionalized gold nanoparticles, can target specific regulatory site in the genome effectively and direct differentiation of MSCs into another cell fate, depending on regime of TFs. For example, myogenic regulatory factor containing NanoScript-MRF differentiates the adipose tissue derived MSCs into muscle cells [92]. The multipotency characteristics represent MSCs as promising candidate for obtaining stable tissue constructs through coaxed 3D organoid culture; however heterogeneous distribution of MSCs slows down cell proliferation, rendering therapeutic applications of MSCs. Adopting two-step culture system for MSCs can yield homogeneous distribution of MSCs in biomaterial scaffolds. For example, fetal-MSCs coaxed in biomaterial when cultured first in rotating bioreactor followed with static culture lead to homogeneous distribution of MSCs in ECM components [7]. Occurrence of dental carries, periodontal disease, and tooth injury can impact individual's health, where bioengineering of teeth can be the alternative option. Coaxing of epithelial-MSCs with dental stem cells into synthetic polymer gives rise to mature teeth unit, which consisted of mature teeth and oral tissue, offering multiple regenerative therapeutics, reviewed elsewhere [52]. Like the tooth decay, both human and animals are prone to orthopedic injuries, affecting bones, joint, tendon, muscles, cartilage, and so forth. Although natural healing potential of bone is sufficient to heal the common injuries, severe trauma and tumor-recession can abrogate germinal potential of bone-forming stem cells. In vitro chondrogenic, osteogenic, and adipogenic potential of MSCs advocates therapeutic applications of MSCs in orthopedic injuries [53]. Seeding of MSCs, coaxed into biomaterial scaffolds, at defective bone tissue, regenerates defective bone tissues, within fourwks of transplantation; by the end of 32wks newly formed tissues integrate into old bone [54]. Osteoblasts, the bone-forming cells, have lesser actin cytoskeleton compared to adipocytes and MSCs. Treatment of MSCs with cytochalasin-D causes rapid transportation of G-actin, leading to osteogenic transformation of MSCs. Furthermore, injection of cytochalasin-D to mice tibia also promotes bone formation within a wk time frame [55]. The bone formation processes in mice, dog, and human are fundamentally similar, so outcomes of research on mice and dogs can be directional for regenerative application to human. Injection of MSCs to femur head of Legg-Calve-Perthes suffering dog heals the bone very fast and reduces the injury associated pain [55]. Degeneration of skeletal muscle and muscle cramps are very common to sledge dogs, animals, and individuals involved in adventurous athletics activities. Direct injection of adipose tissue derived MSCs to tear-site of semitendinosus muscle in dogs heals injuries much faster than traditional therapies [56]. Damage effect treatment for heart muscle regeneration is much more complex than regeneration of skeletal muscles, which needs high grade fine-tuned coordination of neurons with muscles. Coaxing of MSCs into alginate gel increases cell retention time that leads to releasing of tissue repairing factors in controlled manner. Transplantation of alginate encapsulated cells to mice heart reduces scar size and increases vascularisation, which leads to restoration of heart functions. Furthermore, transplanted MSCs face host inhospitable inflammatory immune responses and other mechanical forces at transplantation site, where encapsulation of cells keeps them away from all sorts of mechanical forces and enables sensing of host tissue microenvironment, and respond accordingly [57]. Ageing, disease, and medicine consumption can cause hair loss, known as alopecia. Although alopecia has no life threatening effects, emotional catchments can lead to psychological disturbance. The available treatments for alopecia include hair transplantation and use of drugs, where drugs are expensive to afford and generation of new hair follicle is challenging. Dermal papillary cells (DPCs), the specialized MSCs localized in hair follicle, are responsible for morphogenesis of hair follicle and hair cycling. The layer-by-layer coating of DPCs, called GAG coating, consists of coating of geletin as outer layer, middle layer of fibroblast growth factor 2 (FGF2) loaded alginate, and innermost layer of geletin. GAG coating creates tissue microenvironment for DPCs that can sustain immunological and mechanical obstacles, supporting generation of hair follicle. Transplantation of GAG-coated DPCs leads to abundant hair growth and maturation of hair follicle, where GAG coating serves as ECM, enhancing intrinsic therapeutic potential of DPCs [58]. During infection, the inflammatory cytokines secreted from host immune cells attract MSCs to the site of inflammation, which modulates inflammatory responses, representing MSCs as key candidate of regenerative medicine for infectious disease therapeutics. Coculture of macrophages (M) and adipose derived MSCs from Leishmania major (LM) susceptible and resistant mice demonstrates that AD-MSCs educate M against LM infection, differentially inducing M1 and M2 phenotype that represents AD-MSC as therapeutic agent for leishmanial therapy [93]. In summary, the multilineage differentiation potential of MSCs, as well as adoption of next-generation organoid culture system, avails MSCs as ideal regenerative medicine candidate.

Umbilical cord, generally thrown at the time of child birth, is the best known source for stem cells, procured in noninvasive manner, having lesser ethical constraints than ESCs. Umbilical cord is rich source of hematopoietic stem cells (HSCs) and MSCs, which possess enormous regeneration potential [94] (; ). The HSCs of cord blood are responsible for constant renewal of all types of blood cells and protective immune cells. The proliferation of HSCs is regulated by Musashi-2 protein mediated attenuation of Aryl hydrocarbon receptor (AHR) signalling in stem cells [95]. UCSCs can be cryopreserved at stem cells banks (; ), in operation by both private and public sector organization. Public stem cells banks operate on donation formats and perform rigorous screening for HLA typing and donated UCSCs remain available to anyone in need, whereas private stem cell banks operation is more personalized, availing cells according to donor consent. Stem cell banking is not so common, even in developed countries. Survey studies find that educated women are more eager to donate UCSCs, but willingness for donation decreases with subsequent deliveries, due to associated cost and safety concerns for preservation [96]. FDA has approved five HSCs for treatment of blood and other immunological complications [97]. The amniotic fluid, drawn during pregnancy for standard diagnostic purposes, is generally discarded without considering its vasculogenic potential. UCSCs are the best alternatives for those patients who lack donors with fully matched HLA typing for peripheral blood and PBMCs and bone marrow [98]. One major issue with UCSCs is number of cells in transplant, fewer cells in transplant require more time for engraftment to mature, and there are also risks of infection and mortality; in that case ex vivo propagation of UCSCs can meet the demand of desired outcomes. There are diverse protocols, available for ex vivo expansion of UCSCs, reviewed elsewhere [99]. Amniotic fluid stem cells (AFSCs), coaxed to fibrin (required for blood clotting, ECM interactions, wound healing, and angiogenesis) hydrogel and PEG supplemented with vascular endothelial growth factor (VEGF), give rise to vascularised tissue, when grafted to mice, suggesting that organoid cultures of UCSCs have promise for generation of biocompatible tissue patches, for treating infants born with congenital heart defects [59]. Retroviral integration of OCT4, KLF4, cMYC, and SOX2 transforms AFSCs into pluripotency stem cells known as AFiPSCs which can be directed to differentiate into extraembryonic trophoblast by BMP2 and BMP4 stimulation, which can be used for regeneration of placental tissues [60]. Wharton's jelly (WJ), the gelatinous substance inside umbilical cord, is rich in mucopolysaccharides, fibroblast, macrophages, and stem cells. The stem cells from UCB and WJ can be transdifferentiated into -cells. Homogeneous nature of WJ-SCs enables better differentiation into -cells; transplantation of these cells to streptozotocin induced diabetic mice efficiently brings glucose level to normal [7]. Easy access and expansion potential and plasticity to differentiate into multiple cell lineages represent WJ as an ideal candidate for regenerative medicine but cells viability changes with passages with maximum viable population at 5th-6th passages. So it is suggested to perform controlled expansion of WJ-MSCS for desired regenerative outcomes [9]. Study suggests that CD34+ expression leads to the best regenerative outcomes, with less chance of host-versus-graft rejection. In vitro expansion of UCSCs, in presence of StemRegenin-1 (SR-1), conditionally expands CD34+ cells [61]. In type I diabetic mellitus (T1DM), T-cell mediated autoimmune destruction of pancreatic -cells occurs, which has been considered as tough to treat. Transplantation of WJ-SCs to recent onset-T1DM patients restores pancreatic function, suggesting that WJ-MSCs are effective in regeneration of pancreatic tissue anomalies [62]. WJ-MSCs also have therapeutic importance for treatment of T2DM. A non-placebo controlled phase I/II clinical trial demonstrates that intravenous and intrapancreatic endovascular injection of WJ-MSCs to T2DM patients controls fasting glucose and glycated haemoglobin through improvement of -cells functions, evidenced by enhanced c-peptides and reduced inflammatory cytokines (IL-1 and IL-6) and T-cells counts [63]. Like diabetes, systematic lupus erythematosus (SLE) also can be treated with WJ-MSCs transplantation. During progression of SLE host immune system targets its own tissue leading to degeneration of renal, cardiovascular, neuronal, and musculoskeletal tissues. A non-placebo controlled follow-up study on 40 SLE patients demonstrates that intravenous infusion of WJ-MSC improves renal functions and decreases systematic lupus erythematosus disease activity index (SLEDAI) and British Isles Lupus Assessment Group (BILAG), and repeated infusion of WJ-MSCs protects the patient from relapse of the disease [64]. Sometimes, host inflammatory immune responses can be detrimental for HSCs transplantation and blood transfusion procedures. Infusion of WJ-MSC to patients, who had allogenic HSCs transplantation, reduces haemorrhage inflammation (HI) of bladder, suggesting that WJ-MSCs are potential stem cells adjuvant in HSCs transplantation and blood transfusion based therapies [100]. Apart from WJ, umbilical cord perivascular space and cord vein are also rich source for obtaining MSCs. The perivascular MSCs of umbilical cord are more primitive than WJ-MSCs and other MSCs from cord suggest that perivascular MSCs might be used as alternatives for WJ-MSCs for regenerative therapeutics outcome [101]. Based on origin, MSCs exhibit differential in vitro and in vivo properties and advocate functional characterization of MSCs, prior to regenerative applications. Emerging evidence suggests that UCSCs can heal brain injuries, caused by neurodegenerative diseases like Alzheimer's, Krabbe's disease, and so forth. Krabbe's disease, the infantile lysosomal storage disease, occurs due to deficiency of myelin synthesizing enzyme (MSE), affecting brain development and cognitive functions. Progression of neurodegeneration finally leads to death of babies aged two. Investigation shows that healing of peripheral nervous system (PNS) and central nervous system (CNS) tissues with Krabbe's disease can be achieved by allogenic UCSCs. UCSCs transplantation to asymptomatic infants with subsequent monitoring for 46 years reveals that UCSCs recover babies from MSE deficiency, improving myelination and cognitive functions, compared to those of symptomatic babies. The survival rate of transplanted UCSCs in asymptomatic and symptomatic infants was 100% and 43%, respectively, suggesting that early diagnosis and timely treatment are critical for UCSCs acceptance for desired therapeutic outcomes. UCSCs are more primitive than BMSCs, so perfect HLA typing is not critically required, representing UCSCs as an excellent source for treatment of all the diseases involving lysosomal defects, like Krabbe's disease, hurler syndrome, adrenoleukodystrophy (ALD), metachromatic leukodystrophy (MLD), Tay-Sachs disease (TSD), and Sandhoff disease [65]. Brain injuries often lead to cavities formation, which can be treated from neuronal parenchyma, generated ex vivo from UCSCs. Coaxing of UCSCs into human originated biodegradable matrix scaffold and in vitro expansion of cells in defined culture conditions lead to formation of neuronal organoids, within threewks' time frame. These organoids structurally resemble brain tissue and consisted of neuroblasts (GFAP+, Nestin+, and Ki67+) and immature stem cells (OCT4+ and SOX2+). The neuroblasts of these organoids further can be differentiated into mature neurons (MAP2+ and TUJ1+) [66]. Administration of high dose of drugs in divesting neuroblastoma therapeutics requires immediate restoration of hematopoiesis. Although BMSCs had been promising in restoration of hematopoiesis UCSCs are sparely used in clinical settings. A case study demonstrates that neuroblastoma patients who received autologous UCSCs survive without any associated side effects [12]. During radiation therapy of neoplasm, spinal cord myelitis can occur, although occurrence of myelitis is a rare event and usually such neurodegenerative complication of spinal cord occurs 624 years after exposure to radiations. Transplantation of allogenic UC-MSCs in laryngeal patients undergoing radiation therapy restores myelination [102]. For treatment of neurodegenerative disease like Alzheimer's disease (AD), amyotrophic lateral sclerosis (ALS), traumatic brain injuries (TBI), Parkinson's, SCI, stroke, and so forth, distribution of transplanted UCSCs is critical for therapeutic outcomes. In mice and rat, injection of UCSCs and subsequent MRI scanning show that transplanted UCSCs migrate to CNS and multiple peripheral organs [67]. For immunomodulation of tumor cells disease recovery, transplantation of allogenic DCs is required. The CD11c+DCs, derived from UCB, are morphologically and phenotypically similar to those of peripheral blood derived CTLs-DCs, suggesting that UCB-DCs can be used for personalized medicine of cancer patient, in need for DCs transplantation [103]. Coculture of UCSCs with radiation exposed human lung fibroblast stops their transdifferentiation, which suggests that factors secreted from UCSCs may restore niche identity of fibroblast, if they are transplanted to lung after radiation therapy [104]. Tearing of shoulder cuff tendon can cause severe pain and functional disability, whereas ultrasound guided transplantation of UCB-MSCs in rabbit regenerates subscapularis tendon in fourwks' time frame, suggesting that UCB-MSCs are effective enough to treat tendons injuries when injected to focal points of tear-site [68]. Furthermore, transplantation of UCB-MSCs to chondral cartilage injuries site in pig knee along with HA hydrogel composite regenerates hyaline cartilage [69], suggesting that UCB-MSCs are effective regenerative medicine candidate for treating cartilage and ligament injuries. Physiologically circulatory systems of brain, placenta, and lungs are similar. Infusion of UCB-MSCs to preeclampsia (PE) induced hypertension mice reduces the endotoxic effect, suggesting that UC-MSCs are potential source for treatment of endotoxin induced hypertension during pregnancy, drug abuse, and other kinds of inflammatory shocks [105]. Transplantation of UCSCs to severe congenital neutropenia (SCN) patients restores neutrophils count from donor cells without any side effect, representing UCSCs as potential alternative for SCN therapy, when HLA matched bone marrow donors are not accessible [106]. In clinical settings, the success of myocardial infarction (MI) treatment depends on ageing, systemic inflammation in host, and processing of cells for infusion. Infusion of human hyaluronan hydrogel coaxed UCSCs in pigs induces angiogenesis, decreases scar area, improves cardiac function at preclinical level, and suggests that the same strategy might be effective for human [107]. In stem cells therapeutics, UCSCs transplantation can be either autologous or allogenic. Sometimes, the autologous UCSCs transplants cannot combat over tumor relapse, observed in Hodgkin's lymphoma (HL), which might require second dose transplantation of allogenic stem cells, but efficacy and tolerance of stem cells transplant need to be addressed, where tumor replace occurs. A case study demonstrates that second dose allogenic transplants of UCSCs effective for HL patients, who had heavy dose in prior transplant, increase the long term survival chances by 30% [10]. Patients undergoing long term peritoneal renal dialysis are prone to peritoneal fibrosis and can change peritoneal structure and failure of ultrafiltration processes. The intraperitoneal (IP) injection of WJ-MSCs prevents methylglyoxal induced programmed cell death and peritoneal wall thickening and fibrosis, suggesting that WJ-MSCs are effective in therapeutics of encapsulating peritoneal fibrosis [70]. In summary, UCB-HSCs, WJ-MSCs, perivascular MSCs, and UCB-MSCs have tissue regeneration potential.

Bone marrow found in soft spongy bones is responsible for formation of all peripheral blood and comprises hematopoietic stem cells (producing blood cells) and stromal cells (producing fat, cartilage, and bones) [108] (; ). Visually bone marrow has two types, red marrow (myeloid tissue; producing RBC, platelets, and most of WBC) and yellow marrow (producing fat cells and some WBC) [108]. Imbalance in marrow composition can culminate to the diseased condition. Since 1980, bone marrow transplantation is widely accepted for cancer therapeutics [109]. In order to avoid graft rejection, HLA typing of donors is a must, but completely matched donors are limited to family members, which hampers allogenic transplantation applications. Since matching of all HLA antigens is not critically required, in that case defining the critical antigens for haploidentical allogenic donor for patients, who cannot find fully matched donor, might relieve from donor constraints. Two-step administration of lymphoid and myeloid BMSCs from haploidentical donor to the patients of aplastic anaemia and haematological malignancies reconstructs host immune system and the outcomes are almost similar to fully matched transplants, which recommends that profiling of critically important HLA is sufficient for successful outcomes of BMSCs transplantation. Haploidentical HLA matching protocol is the major process for minorities and others who do not have access to matched donor [71]. Furthermore, antigen profiling is not the sole concern for BMSCs based therapeutics. For example, restriction of HIV1 (human immune deficiency virus) infection is not feasible through BMSCs transplantation because HIV1 infection is mediated through CD4+ receptors, chemokine CXC motif receptor 4 (CXCR4), and chemokine receptor 5 (CCR5) for infecting and propagating into T helper (Th), monocytes, macrophages, and dendritic cells (DCs). Genetic variation in CCR2 and CCR5 receptors is also a contributory factor; mediating protection against infection has been reviewed elsewhere [110]. Engineering of hematopoietic stem and progenitor cells (HSPCs) derived CD4+ cells to express HIV1 antagonistic RNA, specifically designed for targeting HIV1 genome, can restrict HIV1 infection, through immune elimination of latently infected CD4+ cells. A single dose infusion of genetically modified (GM), HIV1 resistant HSPCs can be the alternative of HIV1 retroviral therapy. In the present scenario stem cells source, patient selection, transplantation-conditioning regimen, and postinfusion follow-up studies are the major factors, which can limit application of HIV1 resistant GM-HSPCs (CD4+) cells application in AIDS therapy [72, 73]. Platelets, essential for blood clotting, are formed from megakaryocytes inside the bone marrow [74]. Due to infection, trauma, and cancer, there are chances of bone marrow failure. To an extent, spongy bone marrow microenvironment responsible for lineage commitment can be reconstructed ex vivo [75]. The ex vivo constructed 3D-scaffolds consisted of microtubule and silk sponge, flooded with chemically defined organ culture medium, which mimics bone marrow environment. The coculture of megakaryocytes and embryonic stem cells (ESCs) in this microenvironment leads to generation of functional platelets from megakaryocytes [75]. The ex vivo 3D-scaffolds of bone microenvironment can stride the path for generation of platelets in therapeutic quantities for regenerative medication of burns [75] and blood clotting associated defects. Accidents, traumatic injuries, and brain stroke can deplete neuronal stem cells (NSCs), responsible for generation of neurons, astrocytes, and oligodendrocytes. Brain does not repopulate NSCs and heal traumatic injuries itself and transplantation of BMSCs also can heal neurodegeneration alone. Lipoic acid (LA), a known pharmacological antioxidant compound used in treatment of diabetic and multiple sclerosis neuropathy when combined with BMSCs, induces neovascularisation at focal cerebral injuries, within 8wks of transplantation. Vascularisation further attracts microglia and induces their colonization into scaffold, which leads to differentiation of BMSCs to become brain tissue, within 16wks of transplantation. In this approach, healing of tissue directly depends on number of BMSCs in transplantation dose [76]. Dental caries and periodontal disease are common craniofacial disease, often requiring jaw bone reconstruction after removal of the teeth. Traditional therapy focuses on functional and structural restoration of oral tissue, bone, and teeth rather than biological restoration, but BMSCs based therapies promise for regeneration of craniofacial bone defects, enabling replacement of missing teeth in restored bones with dental implants. Bone marrow derived CD14+ and CD90+ stem and progenitor cells, termed as tissue repair cells (TRC), accelerate alveolar bone regeneration and reconstruction of jaw bone when transplanted in damaged craniofacial tissue, earlier to oral implants. Hence, TRC therapy reduces the need of secondary bone grafts, best suited for severe defects in oral bone, skin, and gum, resulting from trauma, disease, or birth defects [77]. Overall, HSCs have great value in regenerative medicine, where stem cells transplantation strategies explore importance of niche in tissue regeneration. Prior to transplantation of BMSCs, clearance of original niche from target tissue is necessary for generation of organoid and organs without host-versus-graft rejection events. Some genetic defects can lead to disorganization of niche, leading to developmental errors. Complementation with human blastocyst derived primary cells can restore niche function of pancreas in pigs and rats, which defines the concept for generation of clinical grade human pancreas in mice and pigs [111]. Similar to other organs, diaphragm also has its own niche. Congenital defects in diaphragm can affect diaphragm functions. In the present scenario functional restoration of congenital diaphragm defects by surgical repair has risk of reoccurrence of defects or incomplete restoration [8]. Decellularization of donor derived diaphragm offers a way for reconstruction of new and functionally compatible diaphragm through niche modulation. Tissue engineering technology based decellularization of diaphragm and simultaneous perfusion of bone marrow mesenchymal stem cells (BM-MSCs) facilitates regeneration of functional scaffolds of diaphragm tissues [8]. In vivo replacement of hemidiaphragm in rats with reseeded scaffolds possesses similar myography and spirometry as it has in vivo in donor rats. These scaffolds retaining natural architecture are devoid of immune cells, retaining intact extracellular matrix that supports adhesion, proliferation, and differentiation of seeded cells [8]. These findings suggest that cadaver obtained diaphragm, seeded with BM-MSCs, can be used for curing patients in need for restoration of diaphragm functions (; ). However, BMSCs are heterogeneous population, which might result in differential outcomes in clinical settings; however clonal expansion of BMSCs yields homogenous cells population for therapeutic application [8]. One study also finds that intracavernous delivery of single clone BMSCs can restore erectile function in diabetic mice [112] and the same strategy might be explored for adult human individuals. The infection of hepatitis C virus (HCV) can cause liver cirrhosis and degeneration of hepatic tissue. The intraparenchymal transplantation of bone marrow mononuclear cells (BMMNCs) into liver tissue decreases aspartate aminotransferase (AST), alanine transaminase (ALT), bilirubin, CD34, and -SMA, suggesting that transplanted BMSCs restore hepatic functions through regeneration of hepatic tissues [113]. In order to meet the growing demand for stem cells transplantation therapy, donor encouragement is always required [8]. The stem cells donation procedure is very simple; with consent donor gets an injection of granulocyte-colony stimulating factor (G-CSF) that increases BMSCs population. Bone marrow collection is done from hip bone using syringe in 4-5hrs, requiring local anaesthesia and within a wk time frame donor gets recovered donation associated weakness.

The field of iPSCs technology and research is new to all other stem cells research, emerging in 2006 when, for the first time, Takahashi and Yamanaka generated ESCs-like cells through genetic incorporation of four factors, Sox2, Oct3/4, Klf4, and c-Myc, into skin fibroblast [3]. Due to extensive nuclear reprogramming, generated iPSCs are indistinguishable from ESCs, for their transcriptome profiling, epigenetic markings, and functional competence [3], but use of retrovirus in transdifferentiation approach has questioned iPSCs technology. Technological advancement has enabled generation of iPSCs from various kinds of adult cells phasing through ESCs or direct transdifferentiation. This section of review outlines most recent advancement in iPSC technology and regenerative applications (; ). Using the new edge of iPSCs technology, terminally differentiated skin cells directly can be transformed into kidney organoids [114], which are functionally and structurally similar to those of kidney tissue in vivo. Up to certain extent kidneys heal themselves; however natural regeneration potential cannot meet healing for severe injuries. During kidneys healing process, a progenitor stem cell needs to become 20 types of cells, required for waste excretion, pH regulation, and restoration of water and electrolytic ions. The procedure for generation of kidney organoids ex vivo, containing functional nephrons, has been identified for human. These ex vivo kidney organoids are similar to fetal first-trimester kidneys for their structure and physiology. Such kidney organoids can serve as model for nephrotoxicity screening of drugs, disease modelling, and organ transplantation. However generation of fully functional kidneys is a far seen event with today's scientific technologies [114]. Loss of neurons in age-related macular degeneration (ARMD) is the common cause of blindness. At preclinical level, transplantation of iPSCs derived neuronal progenitor cells (NPCs) in rat limits progression of disease through generation of 5-6 layers of photoreceptor nuclei, restoring visual acuity [78]. The various approaches of iPSCs mediated retinal regeneration including ARMD have been reviewed elsewhere [79]. Placenta, the cordial connection between mother and developing fetus, gets degenerated in certain pathophysiological conditions. Nuclear programming of OCT4 knock-out (KO) and wild type (WT) mice fibroblast through transient expression of GATA3, EOMES, TFAP2C, and +/ cMYC generates transgene independent trophoblast stem-like cells (iTSCs), which are highly similar to blastocyst derived TSCs for DNA methylation, H3K7ac, nucleosome deposition of H2A.X, and other epigenetic markings. Chimeric differentiation of iTSCs specifically gives rise to haemorrhagic lineages and placental tissue, bypassing pluripotency phase, opening an avenue for generation of fully functional placenta for human [115]. Neurodegenerative disease like Alzheimer's and obstinate epilepsies can degenerate cerebrum, controlling excitatory and inhibitory signals of the brain. The inhibitory tones in cerebral cortex and hippocampus are accounted by -amino butyric acid secreting (GABAergic) interneurons (INs). Loss of these neurons often leads to progressive neurodegeneration. Genomic integration of Ascl1, Dlx5, Foxg1, and Lhx6 to mice and human fibroblast transforms these adult cells into GABAergic-INs (iGABA-INs). These cells have molecular signature of telencephalic INs, release GABA, and show inhibition to host granule neuronal activity [81]. Transplantation of these INs in developing embryo cures from genetic and acquired seizures, where transplanted cells disperse and mature into functional neuronal circuits as local INs [82]. Dorsomorphin and SB-431542 mediated inhibition of TGF- and BMP signalling direct transformation of human iPSCs into cortical spheroids. These cortical spheroids consisted of both peripheral and cortical neurons, surrounded by astrocytes, displaying transcription profiling and electrophysiology similarity with developing fetal brain and mature neurons, respectively [83]. The underlying complex biology and lack of clear etiology and genetic reprogramming and difficulty in recapitulation of brain development have barred understanding of pathophysiology of autism spectrum disorder (ASD) and schizophrenia. 3D organoid cultures of ASD patient derived iPSC generate miniature brain organoid, resembling fetal brain few months after gestation. The idiopathic conditions of these organoids are similar with brain of ASD patients; both possess higher inhibitory GABAergic neurons with imbalanced neuronal connection. Furthermore these organoids express forkhead Box G1 (FOXG1) much higher than normal brain tissue, which explains that FOXG1 might be the leading cause of ASD [84]. Degeneration of other organs and tissues also has been reported, like degeneration of lungs which might occur due to tuberculosis infection, fibrosis, and cancer. The underlying etiology for lung degeneration can be explained through organoid culture. Coaxing of iPSC into inert biomaterial and defined culture leads to formation of lung organoids that consisted of epithelial and mesenchymal cells, which can survive in culture for months. These organoids are miniature lung, resemble tissues of large airways and alveoli, and can be used for lung developmental studies and screening of antituberculosis and anticancer drugs [87]. The conventional multistep reprogramming for iPSCs consumes months of time, while CRISPER-Cas9 system based episomal reprogramming system that combines two steps together enables generation of ESCs-like cells in less than twowks, reducing the chances of culture associated genetic abrasions and unwanted epigenetic [80]. This approach can yield single step ESCs-like cells in more personalized way from adults with retinal degradation and infants with severe immunodeficiency, involving correction for genetic mutation of OCT4 and DNMT3B [80]. The iPSCs expressing anti-CCR5-RNA, which can be differentiated into HIV1 resistant macrophages, have applications in AIDS therapeutics [88]. The diversified immunotherapeutic application of iPSCs has been reviewed elsewhere [89]. The -1 antitrypsin deficiency (A1AD) encoded by serpin peptidase inhibitor clade A member 1 (SERPINA1) protein synthesized in liver protects lungs from neutrophils elastase, the enzyme causing disruption of lungs connective tissue. A1AD deficiency is common cause of both lung and liver disease like chronic obstructive pulmonary disease (COPD) and liver cirrhosis. Patient specific iPSCs from lung and liver cells might explain pathophysiology of A1AD deficiency. COPD patient derived iPSCs show sensitivity to toxic drugs which explains that actual patient might be sensitive in similar fashion. It is known that A1AD deficiency is caused by single base pair mutation and correction of this mutation fixes the A1AD deficiency in hepatic-iPSCs [85]. The high order brain functions, like emotions, anxiety, sleep, depression, appetite, breathing heartbeats, and so forth, are regulated by serotonin neurons. Generation of serotonin neurons occurs prior to birth, which are postmitotic in their nature. Any sort of developmental defect and degeneration of serotonin neurons might lead to neuronal disorders like bipolar disorder, depression, and schizophrenia-like psychiatric conditions. Manipulation of Wnt signalling in human iPSCs in defined culture conditions leads to an in vitro differentiation of iPSCs to serotonin-like neurons. These iPSCs-neurons primarily localize to rhombomere 2-3 segment of rostral raphe nucleus, exhibit electrophysiological properties similar to serotonin neurons, express hydroxylase 2, the developmental marker, and release serotonin in dose and time dependent manner. Transplantation of these neurons might cure from schizophrenia, bipolar disorder, and other neuropathological conditions [116]. The iPSCs technology mediated somatic cell reprogramming of ventricular monocytes results in generation of cells, similar in morphology and functionality with PCs. SA note transplantation of PCs to large animals improves rhythmic heart functions. Pacemaker needs very reliable and robust performance so understanding of transformation process and site of transplantation are the critical aspect for therapeutic validation of iPSCs derived PCs [28]. Diabetes is a major health concern in modern world, and generation of -cells from adult tissue is challenging. Direct reprogramming of skin cells into pancreatic cells, bypassing pluripotency phase, can yield clinical grade -cells. This reprogramming strategy involves transformation of skin cells into definitive endodermal progenitors (cDE) and foregut like progenitor cells (cPF) intermediates and subsequent in vitro expansion of these intermediates to become pancreatic -cells (cPB). The first step is chemically complex and can be understood as nonepisomal reprogramming on day one with pluripotency factors (OCT4, SOX2, KLF4, and hair pin RNA against p53), then supplementation with GFs and chemical supplements on day seven (EGF, bFGF, CHIR, NECA, NaB, Par, and RG), and two weeks later (Activin-A, CHIR, NECA, NaB, and RG) yielding DE and cPF [86]. Transplantation of cPB yields into glucose stimulated secretion of insulin in diabetic mice defines that such cells can be explored for treatment of T1DM and T2DM in more personalized manner [86]. iPSCs represent underrated opportunities for drug industries and clinical research laboratories for development of therapeutics, but safety concerns might limit transplantation applications (; ) [117]. Transplantation of human iPSCs into mice gastrula leads to colonization and differentiation of cells into three germ layers, evidenced with clinical developmental fat measurements. The acceptance of human iPSCs by mice gastrula suggests that correct timing and appropriate reprogramming regime might delimit human mice species barrier. Using this fact of species barrier, generation of human organs in closely associated primates might be possible, which can be used for treatment of genetic factors governed disease at embryo level itself [118]. In summary, iPSCs are safe and effective for treatment of regenerative medicine.

The unstable growth of human population threatens the existence of wildlife, through overexploitation of natural habitats and illegal killing of wild animals, leading many species to face the fate of being endangered and go for extinction. For wildlife conservation, the concept of creation of frozen zoo involves preservation of gene pool and germ plasm from threatened and endangered species (). The frozen zoo tissue samples collection from dead or live animal can be DNA, sperms, eggs, embryos, gonads, skin, or any other tissue of the body [119]. Preserved tissue can be reprogrammed or transdifferentiated to become other types of tissues and cells, which opens an avenue for conservation of endangered species and resurrection of life (). The gonadal tissue from young individuals harbouring immature tissue can be matured in vivo and ex vivo for generation of functional gametes. Transplantation of SSCs to testis of male from the same different species can give rise to spermatozoa of donor cells [120], which might be used for IVF based captive breeding of wild animals. The most dangerous fact in wildlife conservation is low genetic diversity, too few reproductively capable animals which cannot maintain adequate genetic diversity in wild or captivity. Using the edge of iPSC technology, pluripotent stem cells can be generated from skin cells. For endangered drill, Mandrillus leucophaeus, and nearly extinct white rhinoceros, Ceratotherium simum cottoni, iPSC has been generated in 2011 [121]. The endangered animal drill (Mandrillus leucophaeus) is genetically very close to human and often suffers from diabetes, while rhinos are genetically far removed from other primates. The progress in iPSCs, from the human point of view, might be transformed for animal research for recapturing reproductive potential and health in wild animals. However, stem cells based interventions in wild animals are much more complex than classical conservation planning and biomedical research has to face. Conversion of iPSC into egg or sperm can open the door for generation of IVF based embryo; those might be transplanted in womb of live counterparts for propagation of population. Recently, iPSCs have been generated for snow leopard (Panthera uncia), native to mountain ranges of central Asia, which belongs to cat family; this breakthrough has raised the possibilities for cryopreservation of genetic material for future cloning and other assisted reproductive technology (ART) applications, for the conservation of cat species and biodiversity. Generation of leopard iPSCs has been achieved through retroviral-system based genomic integration of OCT4, SOX2, KLF4, cMYC, and NANOG. These iPSCs from snow leopard also open an avenue for further transformation of iPSCs into gametes [122]. The in vivo maturation of grafted tissue depends both on age and on hormonal status of donor tissue. These facts are equally applicable to accepting host. Ectopic xenografts of cryopreserved testis tissue from Indian spotted deer (Moschiola indica) to nude mice yielded generation of spermatocytes [123], suggesting that one-day procurement of functional sperm from premature tissue might become a general technique in wildlife conservation. In summary, tissue biopsies from dead or live animals can be used for generation of iPSCs and functional gametes; those can be used in assisted reproductive technology (ART) for wildlife conservation.

The spectacular progress in the field of stem cells research represents great scope of stem cells regenerative therapeutics. It can be estimated that by 2020 or so we will be able to produce wide array of tissue, organoid, and organs from adult stem cells. Inductions of pluripotency phenotypes in terminally differentiated adult cells have better therapeutic future than ESCs, due to least ethical constraints with adult cells. In the coming future, there might be new pharmaceutical compounds; those can activate tissue specific stem cells, promote stem cells to migrate to the side of tissue injury, and promote their differentiation to tissue specific cells. Except few countries, the ongoing financial and ethical hindrance on ESCs application in regenerative medicine have more chance for funding agencies to distribute funding for the least risky projects on UCSCs, BMSCs, and TSPSCs from biopsies. The existing stem cells therapeutics advancements are more experimental and high in cost; due to that application on broad scale is not feasible in current scenario. In the near future, the advancements of medical science presume using stem cells to treat cancer, muscles damage, autoimmune disease, and spinal cord injuries among a number of impairments and diseases. It is expected that stem cells therapies will bring considerable benefits to the patients suffering from wide range of injuries and disease. There is high optimism for use of BMSCs, TSPSCs, and iPSCs for treatment of various diseases to overcome the contradictions associated with ESCs. For advancement of translational application of stem cells, there is a need of clinical trials, which needs funding rejoinder from both public and private organizations. The critical evaluation of regulatory guidelines at each phase of clinical trial is a must to comprehend the success and efficacy in time frame.

Dr. Anuradha Reddy from Centre for Cellular and Molecular Biology Hyderabad and Mrs. Sarita Kumari from Department of Yoga Science, BU, Bhopal, India, are acknowledged for their critical suggestions and comments on paper.

There are no competing interests associated with this paper.

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Stem Cells Applications in Regenerative Medicine and ...

Stem cell therapy, sometimes called regenerative medicine, is one of the most exciting areas of the life sciences sector right now.

Since the pandemic, the sector has emerged into the publics spotlight with new developments in mRNA-based vaccines and therapies.

Nasdaq is the obvious breeding ground for world-class stem cell companies with the likes of Moderna and BioNTech, and lesser known names like Anavex and Enochian.

In Australia, Mesoblast (ASX:MSB) has long been the local poster child for the regenerative medicine industry.

Mesoblast has developed a platform of innovative cellular medicines, but the company has struggled since the FDA rejected its drug in October last year.

Now, other ASX companies like Cynata Therapeutics (ASX:CYP)are making rapid progress to take over the mantle from MSB in this hot field.

Cynata is developing a mesenchymal stem cells (or MSC) technology, which it says has huge therapeutic potential for numerous unmet medical needs.

This includes asthma, heart attack, sepsis, and acute respiratory distress syndrome (ARDS), which all add up to a market opportunity worth $46bn, says the company.

According to CEO Dr Ross Macdonald, who spoke to Stockhead today, MSC is the hottest segment of stem cell therapy at the moment, and has gained a lot of attention recently.

There is a huge interest, and theres been more than 1000 clinical trials conducted around the world using MSC, Dr Macdonald told Stockhead.

He explains that the humans immune system controls many of the bodys functions responsible for repairing tissue after injury or disease, and defending against invading germs like viruses or bacteria.

And just like an orchestral conductor, MSC seems to be playing a central role in that coordination within our immune system.

We now have a firm understanding of how those cells coordinate the bodys responses, and can use that knowledge to enhance those processes that they control, Dr Macdonald explained.

In short, MSC therapies work by expressing a variety of chemokines and cytokines that aid in repair of degraded tissue, restoration of normal tissue metabolism and, most importantly, counteracting inflammation.

And because MSCs play that co-ordination role within the immune system, they can be used to treat different diseases.

However theres one big problem with cell-based therapies, and its not to do with the safety and efficacy.

Its how to manufacture these products on a mass scale, that is the greatest challenge right now, says Dr Macdonald.

Unlike aspirin where it can be synthesised in a chemical lab and produced in bulk, manufacturing a living drug like a cell is a whole lot more complicated.

But that big challenge is the exact area of strength and competitive advantage that Cynata has, Dr Macdonald told Stockhead.

He says Cynata has a technology platform which allows it to manufacture essentially limitless quantities of MSCs, consistently and economically.

Dr Macdonald explains there are two approaches to using cell therapy, the autologous and the allogeneic approach.

The autologous approach is where the patient themselves serves as their own donor.

This is obviously bespoke and inefficient, because the drug can only be manufactured for that one patient, and is obviously not an industrialised process, he said.

But by taking an allogeneic approach, Cynata has the ability to start with a one time donation of cells from one single donor.

Well never have to go back to that human donor ever again, so our process of producing cells has become a very much more typical industrialised process.

The company has a patent for this, with two clinical trials underway and two more under preparation.

A Phase 3 clinical trial for osteoarthritis which is funded by a NHMRC grant has progressed the furthest, while a Phase 2 trial in COVID-19 is ongoing.

Meanwhile a Phase 1 study in GvHD, which was published in prestigious journal Nature Medicine, is probably the closest to commercialisation according to Dr Macdonald.

GvHD is a challenging disease which occurs in patients who have had a bone marrow transplant as part of their chemotherapy treatment for cancer.

Chemo is still very much a sledgehammer therapy where you use very toxic drugs that do kill the cancer cells, but they also kill the surrounding healthy cells that grow hair and bone marrow.

Unfortunately for many patients, the bone marrow transplant reacts against their body and starts to attack all of the tissues in the body, and its ultimately fatal.

Its a horrible death, destroying the lungs, liver, intestines and the skin, Macdonald explains.

Cynatas MSC therapy has been shown to reset that reaction, so the patient can recover from the GvHD, and also recover from their underlying cancer.

With all these clinical trials concurrently under way, Macdonald believes there is a clear significant upside potential for Cynata, particularly given its small market cap of $70m compared to other similar plays like Mesoblast ($1 billion market cap).

Osteopore (ASX:OSX) focuses in bones and specialises in the production of 3D printed bioresorbable implants that are used in surgical procedures to assist with the natural stages of bone healing.

The 3D bio-printer makes a scaffold that mimics bone, with a patented micro-architecture which traps the patients own stem cells.

Orthocell (ASX:OCC) develops collagen medical devices and cellular therapies for the repair and regeneration of human tendons, bone, nerve and cartilage defects.

Its flagship product, the CelGro, is a naturally derived collagen medical device for tissue repair.

Aroa Biosurgery (ASX:ARX) develops FDA-approved medical devices for wounds and tissue repair using its extracellular matrix (ECM) technology, mainly in the United States.

Recent study shows 100% success rates from the use of its Myriad product when patients underwent surgical reconstruction of exposed vital structures such as bone and tendon.

Regeneus (ASX:RGS) Progenza is a cellular therapy targeting pain and inflammation which uses Secretome to improve not only the resident tissue, but the MSCs themselves.

It fills a gap in the current treatment market for osteoarthritis, by providing disease modification and pain relief to address patient symptoms.

Anteris Technologies (ASX:AVR) claims that its Adapt Technology is the first and only bio-scaffold technology that completely re-engineers xenograft tissue into a pure collagen scaffold.

A recent study indicated that Adapt-treated tissue has superior anti-calcification attributes compared with tissues used in competitor valves.

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Mesoblast has long been the one poster child for stem cell therapy. Now Cynata and other ASX stocks have e ... - Stockhead

KENILWORTH, N.J.--(BUSINESS WIRE)--Merck (NYSE: MRK), known as MSD outside the United States and Canada, today announced that the U.S. Food and Drug Administration (FDA) has approved KEYTRUDA, Mercks anti-PD-1 therapy, for the adjuvant treatment of patients with renal cell carcinoma (RCC) at intermediate-high or high risk of recurrence following nephrectomy, or following nephrectomy and resection of metastatic lesions. The approval is based on data from the pivotal Phase 3 KEYNOTE-564 trial, in which KEYTRUDA demonstrated a statistically significant improvement in disease-free survival (DFS), reducing the risk of disease recurrence or death by 32% (HR=0.68 [95% CI, 0.53-0.87]; p=0.0010) compared to placebo. Median DFS has not been reached for either group.

Despite decades of research, limited adjuvant treatment options have been available for earlier-stage renal cell carcinoma patients who are often at risk for recurrence. In KEYNOTE-564, pembrolizumab reduced the risk of disease recurrence or death by 32%, providing a promising new treatment option for certain patients at intermediate-high or high risk of recurrence, said Dr. Toni K. Choueiri, director, Lank Center for Genitourinary Oncology, Dana-Farber Cancer Institute, and professor of medicine, Harvard Medical School. With this FDA approval, pembrolizumab may address a critical unmet treatment need and has the potential to become a new standard of care in the adjuvant setting for appropriately selected patients.

Immune-mediated adverse reactions, which may be severe or fatal, can occur in any organ system or tissue and can affect more than one body system simultaneously. Immune-mediated adverse reactions can occur at any time during or after treatment with KEYTRUDA, including pneumonitis, colitis, hepatitis, endocrinopathies, nephritis, dermatologic reactions, solid organ transplant rejection, and complications of allogeneic hematopoietic stem cell transplantation. Important immune-mediated adverse reactions listed here may not include all possible severe and fatal immune-mediated adverse reactions. Early identification and management of immune-mediated adverse reactions are essential to ensure safe use of KEYTRUDA. Based on the severity of the adverse reaction, KEYTRUDA should be withheld or permanently discontinued and corticosteroids administered if appropriate. KEYTRUDA can also cause severe or life-threatening infusion-related reactions. Based on its mechanism of action, KEYTRUDA can cause fetal harm when administered to a pregnant woman. For more information, see Selected Important Safety Information below.

KEYTRUDA is foundational for the treatment of patients with certain advanced cancers, and this approval marks the fourth indication for KEYTRUDA in earlier stages of cancer, said Dr. Scot Ebbinghaus, vice president, clinical research, Merck Research Laboratories. KEYTRUDA is now the first immunotherapy approved for the adjuvant treatment of certain patients with renal cell carcinoma. This milestone is a testament to our commitment to help more people living with cancer.

In RCC, Merck has a broad clinical development program exploring KEYTRUDA, as monotherapy or in combination, as well as other investigational products across multiple settings and stages of RCC, including adjuvant and advanced or metastatic disease.

Data Supporting the Approval

KEYTRUDA demonstrated a statistically significant improvement in DFS in patients with RCC at intermediate-high or high risk of recurrence following nephrectomy, or following nephrectomy and resection of metastatic lesions compared with placebo (HR=0.68 [95% CI, 0.53-0.87]; p=0.0010). The trial will continue to assess overall survival (OS) as a secondary outcome measure.

In KEYNOTE-564, the median duration of exposure to KEYTRUDA was 11.1 months (range, 1 day to 14.3 months). Serious adverse reactions occurred in 20% of these patients receiving KEYTRUDA. Serious adverse reactions (1%) were acute kidney injury, adrenal insufficiency, pneumonia, colitis and diabetic ketoacidosis (1% each). Fatal adverse reactions occurred in 0.2% of those treated with KEYTRUDA, including one case of pneumonia. Adverse reactions leading to discontinuation occurred in 21% of patients receiving KEYTRUDA; the most common (1%) were increased alanine aminotransferase (1.6%), colitis and adrenal insufficiency (1% each). The most common adverse reactions (all grades 20%) in the KEYTRUDA arm were musculoskeletal pain (41%), fatigue (40%), rash (30%), diarrhea (27%), pruritus (23%) and hypothyroidism (21%).

About KEYNOTE-564

KEYNOTE-564 (ClinicalTrials.gov, NCT03142334) is a multicenter, randomized, double-blind, placebo-controlled Phase 3 trial evaluating KEYTRUDA as adjuvant therapy for RCC in 994 patients with intermediate-high or high risk of recurrence of RCC or M1 no evidence of disease (NED). Patients must have undergone a partial nephroprotective or radical complete nephrectomy (and complete resection of solid, isolated, soft tissue metastatic lesion[s] in M1 NED participants) with negative surgical margins for at least four weeks prior to the time of screening. Patients were excluded from the trial if they had received prior systemic therapy for advanced RCC. Patients with active autoimmune disease or a medical condition that required immunosuppression were also ineligible. The major efficacy outcome measure was investigator-assessed DFS, defined as time to recurrence, metastasis or death. An additional outcome measure was OS. Patients were randomized (1:1) to receive KEYTRUDA 200 mg administered intravenously every three weeks or placebo for up to one year until disease recurrence or unacceptable toxicity.

About Renal Cell Carcinoma (RCC)

Renal cell carcinoma is by far the most common type of kidney cancer; about nine out of 10 kidney cancer diagnoses are RCCs. Renal cell carcinoma is about twice as common in men than in women. Most cases of RCC are discovered incidentally during imaging tests for other abdominal diseases. Worldwide, it is estimated there were more than 431,000 new cases of kidney cancer diagnosed and more than 179,000 deaths from the disease in 2020. In the U.S., it is estimated there will be more than 76,000 new cases of kidney cancer diagnosed and almost 14,000 deaths from the disease in 2021.

About Mercks Early-Stage Cancer Clinical Program

Finding cancer at an earlier stage may give patients a greater chance of long-term survival. Many cancers are considered most treatable and potentially curable in their earliest stage of disease. Building on the strong understanding of the role of KEYTRUDA in later-stage cancers, Merck is studying KEYTRUDA in earlier disease states, with approximately 20 ongoing registrational studies across multiple types of cancer.

About KEYTRUDA (pembrolizumab) Injection, 100 mg

KEYTRUDA is an anti-programmed death receptor-1 (PD-1) therapy that works by increasing the ability of the bodys immune system to help detect and fight tumor cells. KEYTRUDA is a humanized monoclonal antibody that blocks the interaction between PD-1 and its ligands, PD-L1 and PD-L2, thereby activating T lymphocytes which may affect both tumor cells and healthy cells.

Merck has the industrys largest immuno-oncology clinical research program. There are currently more than 1,600 trials studying KEYTRUDA across a wide variety of cancers and treatment settings. The KEYTRUDA clinical program seeks to understand the role of KEYTRUDA across cancers and the factors that may predict a patient's likelihood of benefitting from treatment with KEYTRUDA, including exploring several different biomarkers.

Selected KEYTRUDA (pembrolizumab) Indications in the U.S.

Melanoma

KEYTRUDA is indicated for the treatment of patients with unresectable or metastatic melanoma.

KEYTRUDA is indicated for the adjuvant treatment of patients with melanoma with involvement of lymph node(s) following complete resection.

Non-Small Cell Lung Cancer

KEYTRUDA, in combination with pemetrexed and platinum chemotherapy, is indicated for the first-line treatment of patients with metastatic nonsquamous non-small cell lung cancer (NSCLC), with no EGFR or ALK genomic tumor aberrations.

KEYTRUDA, in combination with carboplatin and either paclitaxel or paclitaxel protein-bound, is indicated for the first-line treatment of patients with metastatic squamous NSCLC.

KEYTRUDA, as a single agent, is indicated for the first-line treatment of patients with NSCLC expressing PD-L1 [tumor proportion score (TPS) 1%] as determined by an FDA-approved test, with no EGFR or ALK genomic tumor aberrations, and is:

KEYTRUDA, as a single agent, is indicated for the treatment of patients with metastatic NSCLC whose tumors express PD-L1 (TPS 1%) as determined by an FDA-approved test, with disease progression on or after platinum-containing chemotherapy. Patients with EGFR or ALK genomic tumor aberrations should have disease progression on FDA-approved therapy for these aberrations prior to receiving KEYTRUDA.

Head and Neck Squamous Cell Cancer

KEYTRUDA, in combination with platinum and fluorouracil (FU), is indicated for the first-line treatment of patients with metastatic or with unresectable, recurrent head and neck squamous cell carcinoma (HNSCC).

KEYTRUDA, as a single agent, is indicated for the first-line treatment of patients with metastatic or with unresectable, recurrent HNSCC whose tumors express PD-L1 [combined positive score (CPS 1)] as determined by an FDA-approved test.

KEYTRUDA, as a single agent, is indicated for the treatment of patients with recurrent or metastatic HNSCC with disease progression on or after platinum-containing chemotherapy.

Classical Hodgkin Lymphoma

KEYTRUDA is indicated for the treatment of adult patients with relapsed or refractory classical Hodgkin lymphoma (cHL).

KEYTRUDA is indicated for the treatment of pediatric patients with refractory cHL, or cHL that has relapsed after 2 or more lines of therapy.

Primary Mediastinal Large B-Cell Lymphoma

KEYTRUDA is indicated for the treatment of adult and pediatric patients with refractory primary mediastinal large B-cell lymphoma (PMBCL), or who have relapsed after 2 or more prior lines of therapy. KEYTRUDA is not recommended for treatment of patients with PMBCL who require urgent cytoreductive therapy.

Urothelial Carcinoma

KEYTRUDA is indicated for the treatment of patients with locally advanced or metastatic urothelial carcinoma (mUC):

Non-muscle Invasive Bladder Cancer

KEYTRUDA is indicated for the treatment of patients with Bacillus Calmette-Guerin-unresponsive, high-risk, non-muscle invasive bladder cancer (NMIBC) with carcinoma in situ with or without papillary tumors who are ineligible for or have elected not to undergo cystectomy.

Microsatellite Instability-High or Mismatch Repair Deficient Cancer

KEYTRUDA is indicated for the treatment of adult and pediatric patients with unresectable or metastatic microsatellite instability-high (MSI-H) or mismatch repair deficient (dMMR) solid tumors that have progressed following prior treatment and who have no satisfactory alternative treatment options.

This indication is approved under accelerated approval based on tumor response rate and durability of response. Continued approval for this indication may be contingent upon verification and description of clinical benefit in the confirmatory trials. The safety and effectiveness of KEYTRUDA in pediatric patients with MSI-H central nervous system cancers have not been established.

Microsatellite Instability-High or Mismatch Repair Deficient Colorectal Cancer

KEYTRUDA is indicated for the treatment of patients with unresectable or metastatic MSI-H or dMMR colorectal cancer (CRC).

Gastric Cancer

KEYTRUDA, in combination with trastuzumab, fluoropyrimidine- and platinum-containing chemotherapy, is indicated for the first-line treatment of patients with locally advanced unresectable or metastatic HER2-positive gastric or gastroesophageal junction (GEJ) adenocarcinoma.

This indication is approved under accelerated approval based on tumor response rate and durability of response. Continued approval for this indication may be contingent upon verification and description of clinical benefit in the confirmatory trials.

Esophageal Cancer

KEYTRUDA is indicated for the treatment of patients with locally advanced or metastatic esophageal or GEJ (tumors with epicenter 1 to 5 centimeters above the GEJ) carcinoma that is not amenable to surgical resection or definitive chemoradiation either:

Cervical Cancer

KEYTRUDA, in combination with chemotherapy, with or without bevacizumab, is indicated for the treatment of patients with persistent, recurrent, or metastatic cervical cancer whose tumors express PD-L1 (CPS 1) as determined by an FDA-approved test.

KEYTRUDA, as a single agent, is indicated for the treatment of patients with recurrent or metastatic cervical cancer with disease progression on or after chemotherapy whose tumors express PD-L1 (CPS 1) as determined by an FDA-approved test.

Hepatocellular Carcinoma

KEYTRUDA is indicated for the treatment of patients with hepatocellular carcinoma (HCC) who have been previously treated with sorafenib. This indication is approved under accelerated approval based on tumor response rate and durability of response. Continued approval for this indication may be contingent upon verification and description of clinical benefit in the confirmatory trials.

Merkel Cell Carcinoma

KEYTRUDA is indicated for the treatment of adult and pediatric patients with recurrent locally advanced or metastatic Merkel cell carcinoma (MCC). This indication is approved under accelerated approval based on tumor response rate and durability of response. Continued approval for this indication may be contingent upon verification and description of clinical benefit in the confirmatory trials.

Renal Cell Carcinoma

KEYTRUDA, in combination with axitinib, is indicated for the first-line treatment of adult patients with advanced renal cell carcinoma (RCC).

KEYTRUDA is indicated for the adjuvant treatment of patients with RCC at intermediate-high or high risk of recurrence following nephrectomy, or following nephrectomy and resection of metastatic lesions.

Tumor Mutational Burden-High Cancer

KEYTRUDA is indicated for the treatment of adult and pediatric patients with unresectable or metastatic tumor mutational burden-high (TMB-H) [10 mutations/megabase] solid tumors, as determined by an FDA-approved test, that have progressed following prior treatment and who have no satisfactory alternative treatment options. This indication is approved under accelerated approval based on tumor response rate and durability of response. Continued approval for this indication may be contingent upon verification and description of clinical benefit in the confirmatory trials. The safety and effectiveness of KEYTRUDA in pediatric patients with TMB-H central nervous system cancers have not been established.

Cutaneous Squamous Cell Carcinoma

KEYTRUDA is indicated for the treatment of patients with recurrent or metastatic cutaneous squamous cell carcinoma (cSCC) or locally advanced cSCC that is not curable by surgery or radiation.

Triple-Negative Breast Cancer

KEYTRUDA is indicated for the treatment of patients with high-risk early-stage triple-negative breast cancer (TNBC) in combination with chemotherapy as neoadjuvant treatment, and then continued as a single agent as adjuvant treatment after surgery.

KEYTRUDA, in combination with chemotherapy, is indicated for the treatment of patients with locally recurrent unresectable or metastatic TNBC whose tumors express PD-L1 (CPS 10) as determined by an FDA-approved test.

Selected Important Safety Information for KEYTRUDA

Severe and Fatal Immune-Mediated Adverse Reactions

KEYTRUDA is a monoclonal antibody that belongs to a class of drugs that bind to either the PD-1 or the PD-L1, blocking the PD-1/PD-L1 pathway, thereby removing inhibition of the immune response, potentially breaking peripheral tolerance and inducing immune-mediated adverse reactions. Immune-mediated adverse reactions, which may be severe or fatal, can occur in any organ system or tissue, can affect more than one body system simultaneously, and can occur at any time after starting treatment or after discontinuation of treatment. Important immune-mediated adverse reactions listed here may not include all possible severe and fatal immune-mediated adverse reactions.

Monitor patients closely for symptoms and signs that may be clinical manifestations of underlying immune-mediated adverse reactions. Early identification and management are essential to ensure safe use of antiPD-1/PD-L1 treatments. Evaluate liver enzymes, creatinine, and thyroid function at baseline and periodically during treatment. For patients with TNBC treated with KEYTRUDA in the neoadjuvant setting, monitor blood cortisol at baseline, prior to surgery, and as clinically indicated. In cases of suspected immune-mediated adverse reactions, initiate appropriate workup to exclude alternative etiologies, including infection. Institute medical management promptly, including specialty consultation as appropriate.

Withhold or permanently discontinue KEYTRUDA depending on severity of the immune-mediated adverse reaction. In general, if KEYTRUDA requires interruption or discontinuation, administer systemic corticosteroid therapy (1 to 2 mg/kg/day prednisone or equivalent) until improvement to Grade 1 or less. Upon improvement to Grade 1 or less, initiate corticosteroid taper and continue to taper over at least 1 month. Consider administration of other systemic immunosuppressants in patients whose adverse reactions are not controlled with corticosteroid therapy.

Immune-Mediated Pneumonitis

KEYTRUDA can cause immune-mediated pneumonitis. The incidence is higher in patients who have received prior thoracic radiation. Immune-mediated pneumonitis occurred in 3.4% (94/2799) of patients receiving KEYTRUDA, including fatal (0.1%), Grade 4 (0.3%), Grade 3 (0.9%), and Grade 2 (1.3%) reactions. Systemic corticosteroids were required in 67% (63/94) of patients. Pneumonitis led to permanent discontinuation of KEYTRUDA in 1.3% (36) and withholding in 0.9% (26) of patients. All patients who were withheld reinitiated KEYTRUDA after symptom improvement; of these, 23% had recurrence. Pneumonitis resolved in 59% of the 94 patients.

Pneumonitis occurred in 8% (31/389) of adult patients with cHL receiving KEYTRUDA as a single agent, including Grades 3-4 in 2.3% of patients. Patients received high-dose corticosteroids for a median duration of 10 days (range: 2 days to 53 months). Pneumonitis rates were similar in patients with and without prior thoracic radiation. Pneumonitis led to discontinuation of KEYTRUDA in 5.4% (21) of patients. Of the patients who developed pneumonitis, 42% interrupted KEYTRUDA, 68% discontinued KEYTRUDA, and 77% had resolution.

Immune-Mediated Colitis

KEYTRUDA can cause immune-mediated colitis, which may present with diarrhea. Cytomegalovirus infection/reactivation has been reported in patients with corticosteroid-refractory immune-mediated colitis. In cases of corticosteroid-refractory colitis, consider repeating infectious workup to exclude alternative etiologies. Immune-mediated colitis occurred in 1.7% (48/2799) of patients receiving KEYTRUDA, including Grade 4 (<0.1%), Grade 3 (1.1%), and Grade 2 (0.4%) reactions. Systemic corticosteroids were required in 69% (33/48); additional immunosuppressant therapy was required in 4.2% of patients. Colitis led to permanent discontinuation of KEYTRUDA in 0.5% (15) and withholding in 0.5% (13) of patients. All patients who were withheld reinitiated KEYTRUDA after symptom improvement; of these, 23% had recurrence. Colitis resolved in 85% of the 48 patients.

Hepatotoxicity and Immune-Mediated Hepatitis

KEYTRUDA as a Single Agent

KEYTRUDA can cause immune-mediated hepatitis. Immune-mediated hepatitis occurred in 0.7% (19/2799) of patients receiving KEYTRUDA, including Grade 4 (<0.1%), Grade 3 (0.4%), and Grade 2 (0.1%) reactions. Systemic corticosteroids were required in 68% (13/19) of patients; additional immunosuppressant therapy was required in 11% of patients. Hepatitis led to permanent discontinuation of KEYTRUDA in 0.2% (6) and withholding in 0.3% (9) of patients. All patients who were withheld reinitiated KEYTRUDA after symptom improvement; of these, none had recurrence. Hepatitis resolved in 79% of the 19 patients.

KEYTRUDA with Axitinib

KEYTRUDA in combination with axitinib can cause hepatic toxicity. Monitor liver enzymes before initiation of and periodically throughout treatment. Consider monitoring more frequently as compared to when the drugs are administered as single agents. For elevated liver enzymes, interrupt KEYTRUDA and axitinib, and consider administering corticosteroids as needed. With the combination of KEYTRUDA and axitinib, Grades 3 and 4 increased alanine aminotransferase (ALT) (20%) and increased aspartate aminotransferase (AST) (13%) were seen at a higher frequency compared to KEYTRUDA alone. Fifty-nine percent of the patients with increased ALT received systemic corticosteroids. In patients with ALT 3 times upper limit of normal (ULN) (Grades 2-4, n=116), ALT resolved to Grades 0-1 in 94%. Among the 92 patients who were rechallenged with either KEYTRUDA (n=3) or axitinib (n=34) administered as a single agent or with both (n=55), recurrence of ALT 3 times ULN was observed in 1 patient receiving KEYTRUDA, 16 patients receiving axitinib, and 24 patients receiving both. All patients with a recurrence of ALT 3 ULN subsequently recovered from the event.

Immune-Mediated Endocrinopathies

Adrenal Insufficiency

KEYTRUDA can cause primary or secondary adrenal insufficiency. For Grade 2 or higher, initiate symptomatic treatment, including hormone replacement as clinically indicated. Withhold KEYTRUDA depending on severity. Adrenal insufficiency occurred in 0.8% (22/2799) of patients receiving KEYTRUDA, including Grade 4 (<0.1%), Grade 3 (0.3%), and Grade 2 (0.3%) reactions. Systemic corticosteroids were required in 77% (17/22) of patients; of these, the majority remained on systemic corticosteroids. Adrenal insufficiency led to permanent discontinuation of KEYTRUDA in <0.1% (1) and withholding in 0.3% (8) of patients. All patients who were withheld reinitiated KEYTRUDA after symptom improvement.

Hypophysitis

KEYTRUDA can cause immune-mediated hypophysitis. Hypophysitis can present with acute symptoms associated with mass effect such as headache, photophobia, or visual field defects. Hypophysitis can cause hypopituitarism. Initiate hormone replacement as indicated. Withhold or permanently discontinue KEYTRUDA depending on severity. Hypophysitis occurred in 0.6% (17/2799) of patients receiving KEYTRUDA, including Grade 4 (<0.1%), Grade 3 (0.3%), and Grade 2 (0.2%) reactions. Systemic corticosteroids were required in 94% (16/17) of patients; of these, the majority remained on systemic corticosteroids. Hypophysitis led to permanent discontinuation of KEYTRUDA in 0.1% (4) and withholding in 0.3% (7) of patients. All patients who were withheld reinitiated KEYTRUDA after symptom improvement.

Thyroid Disorders

KEYTRUDA can cause immune-mediated thyroid disorders. Thyroiditis can present with or without endocrinopathy. Hypothyroidism can follow hyperthyroidism. Initiate hormone replacement for hypothyroidism or institute medical management of hyperthyroidism as clinically indicated. Withhold or permanently discontinue KEYTRUDA depending on severity. Thyroiditis occurred in 0.6% (16/2799) of patients receiving KEYTRUDA, including Grade 2 (0.3%). None discontinued, but KEYTRUDA was withheld in <0.1% (1) of patients.

Hyperthyroidism occurred in 3.4% (96/2799) of patients receiving KEYTRUDA, including Grade 3 (0.1%) and Grade 2 (0.8%). It led to permanent discontinuation of KEYTRUDA in <0.1% (2) and withholding in 0.3% (7) of patients. All patients who were withheld reinitiated KEYTRUDA after symptom improvement. Hypothyroidism occurred in 8% (237/2799) of patients receiving KEYTRUDA, including Grade 3 (0.1%) and Grade 2 (6.2%). It led to permanent discontinuation of KEYTRUDA in <0.1% (1) and withholding in 0.5% (14) of patients. All patients who were withheld reinitiated KEYTRUDA after symptom improvement. The majority of patients with hypothyroidism required long-term thyroid hormone replacement. The incidence of new or worsening hypothyroidism was higher in 1185 patients with HNSCC, occurring in 16% of patients receiving KEYTRUDA as a single agent or in combination with platinum and FU, including Grade 3 (0.3%) hypothyroidism. The incidence of new or worsening hypothyroidism was higher in 389 adult patients with cHL (17%) receiving KEYTRUDA as a single agent, including Grade 1 (6.2%) and Grade 2 (10.8%) hypothyroidism.

Type 1 Diabetes Mellitus (DM), Which Can Present With Diabetic Ketoacidosis

Monitor patients for hyperglycemia or other signs and symptoms of diabetes. Initiate treatment with insulin as clinically indicated. Withhold KEYTRUDA depending on severity. Type 1 DM occurred in 0.2% (6/2799) of patients receiving KEYTRUDA. It led to permanent discontinuation in <0.1% (1) and withholding of KEYTRUDA in <0.1% (1) of patients. All patients who were withheld reinitiated KEYTRUDA after symptom improvement.

Immune-Mediated Nephritis With Renal Dysfunction

KEYTRUDA can cause immune-mediated nephritis. Immune-mediated nephritis occurred in 0.3% (9/2799) of patients receiving KEYTRUDA, including Grade 4 (<0.1%), Grade 3 (0.1%), and Grade 2 (0.1%) reactions. Systemic corticosteroids were required in 89% (8/9) of patients. Nephritis led to permanent discontinuation of KEYTRUDA in 0.1% (3) and withholding in 0.1% (3) of patients. All patients who were withheld reinitiated KEYTRUDA after symptom improvement; of these, none had recurrence. Nephritis resolved in 56% of the 9 patients.

Immune-Mediated Dermatologic Adverse Reactions

KEYTRUDA can cause immune-mediated rash or dermatitis. Exfoliative dermatitis, including Stevens-Johnson syndrome, drug rash with eosinophilia and systemic symptoms, and toxic epidermal necrolysis, has occurred with antiPD-1/PD-L1 treatments. Topical emollients and/or topical corticosteroids may be adequate to treat mild to moderate nonexfoliative rashes. Withhold or permanently discontinue KEYTRUDA depending on severity. Immune-mediated dermatologic adverse reactions occurred in 1.4% (38/2799) of patients receiving KEYTRUDA, including Grade 3 (1%) and Grade 2 (0.1%) reactions. Systemic corticosteroids were required in 40% (15/38) of patients. These reactions led to permanent discontinuation in 0.1% (2) and withholding of KEYTRUDA in 0.6% (16) of patients. All patients who were withheld reinitiated KEYTRUDA after symptom improvement; of these, 6% had recurrence. The reactions resolved in 79% of the 38 patients.

Other Immune-Mediated Adverse Reactions

The following clinically significant immune-mediated adverse reactions occurred at an incidence of <1% (unless otherwise noted) in patients who received KEYTRUDA or were reported with the use of other antiPD-1/PD-L1 treatments. Severe or fatal cases have been reported for some of these adverse reactions. Cardiac/Vascular: Myocarditis, pericarditis, vasculitis; Nervous System: Meningitis, encephalitis, myelitis and demyelination, myasthenic syndrome/myasthenia gravis (including exacerbation), Guillain-Barr syndrome, nerve paresis, autoimmune neuropathy; Ocular: Uveitis, iritis and other ocular inflammatory toxicities can occur. Some cases can be associated with retinal detachment. Various grades of visual impairment, including blindness, can occur. If uveitis occurs in combination with other immune-mediated adverse reactions, consider a Vogt-Koyanagi-Harada-like syndrome, as this may require treatment with systemic steroids to reduce the risk of permanent vision loss; Gastrointestinal: Pancreatitis, to include increases in serum amylase and lipase levels, gastritis, duodenitis; Musculoskeletal and Connective Tissue: Myositis/polymyositis, rhabdomyolysis (and associated sequelae, including renal failure), arthritis (1.5%), polymyalgia rheumatica; Endocrine: Hypoparathyroidism; Hematologic/Immune: Hemolytic anemia, aplastic anemia, hemophagocytic lymphohistiocytosis, systemic inflammatory response syndrome, histiocytic necrotizing lymphadenitis (Kikuchi lymphadenitis), sarcoidosis, immune thrombocytopenic purpura, solid organ transplant rejection.

Infusion-Related Reactions

KEYTRUDA can cause severe or life-threatening infusion-related reactions, including hypersensitivity and anaphylaxis, which have been reported in 0.2% of 2799 patients receiving KEYTRUDA. Monitor for signs and symptoms of infusion-related reactions. Interrupt or slow the rate of infusion for Grade 1 or Grade 2 reactions. For Grade 3 or Grade 4 reactions, stop infusion and permanently discontinue KEYTRUDA.

Complications of Allogeneic Hematopoietic Stem Cell Transplantation (HSCT)

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FDA Approves Merck's KEYTRUDA (pembrolizumab) as Adjuvant Therapy for Certain Patients With Renal Cell Carcinoma (RCC) Following Surgery - Business...

Passage Of California Stem Cell Proposition Boosts Research

For the last decade and more, Stem Cell research and regenerative medicine have been the rave of the healthcare industry, a delicate area that has seen steady advancements over the last few years.

The promise of regenerative medicine is simple but profound that one day medical experts will be able to diagnose a problem, remove some of our body cells called stem cells and use them to grow a cure for our ailment. Using our body cells will create a highly personalized therapy attuned to our genes and systems.

The terminologies often used in this field of medicine can get a bit fuzzy for the uninitiated, so in this article, I have relied heavily on the insights of Christian Drapeau, a neurophysiologist and stem cell expert.

Drapeau was one of the first voices who discovered and began to speak about stem cells being the bodys repair system in the early 2000s. Since then, he has gone on to discover the first stem cell mobilizer, and his studies and research delivered the proof of concept that the AFA (Aphanizomenon flos-aquae) extract was capable of enhancing repair from muscle injury.

Christian Drapeau is also the founder of Kalyagen, astem cell research-based company, and the manufacturers of Stemregen. This stem cell mobilizer combines some of the most effective stem cell mobilizers Drapeau has discovered to create an effective treatment for varying diseases.

How exactly do stem cell-based treatments work? And how is it delivering on its promise of boosting our abilities to regenerate or self-heal?

Drapeau explains the concept for us;

Stem cells are mother cells or blank cells produced by the bone marrow. As they are released from the bone marrow stem cells can travel to any organ and tissue of the body, where they can transform into cells of that tissue.Stem cells constitute the repair system of the body.

The discovery of this function has led scientists on a long journey to discover how to use stem cells to cure diseases, which are essentially caused by cellular loss. Diseases like Diabetes and age-related degenerative diseases are all associated with the loss of a type of cell or cellular function.

However, what Drapeaus research has unearthed over the last few decades is that there are naturally occurring substances that show a demonstrated ability to induce the release of stem cells from the bone marrow. These stem cells then enter the bloodstream, from where they can travel to sites of cell deficiency or injury in the body to aid healing and regeneration. This process is referred to as Endogenous Stem Cell Mobilization (ESCM).

Stemregen is our most potent creation so far, explains Drapeau, and it has shown excellent results with the treatment of problems in the endocrine system, muscles, kidneys, respiratory systems, and even with issues of erectile dysfunction.

Despite the stunning advancements that have been made so far, a concern that both Drapeau and I share is how this innovation can be merged with another exciting innovation; AI.

Is it even a possibility? Drapeau, an AI enthusiast, explains that AI has already been a life-saver in stem cell research and has even more potential.

On closer observation, there are a few areas in which AI has greatly benefited stem cell research and regenerative medicine.

One obstacle that scientists have consistently faced with delivering the full promise of regenerative medicine is the complexity of the available data.Cells are so different from each other that scientists can struggle with predicting what the cells will do in any given therapeutic scenario. Scientists are faced with millions of ways that medical therapy could go wrong.

Most AI experts believe that in almost any field, AI can provide a solution whenever there is a problem with data analysis and predictive analysis.

Carl Simon, a biologist at the National Institute of Standards and Technology (NIST) and Nicholas Schaub recentlytested this hypothesiswhen they applied Deep Neural Networks (DNN), an AI program to the data they had collected in their experiments on eye cells. Their research revolved around causes and solutions for age-related eye degeneration. The results were stunning; the AI made only one incorrect prediction about cell changes out of 36 predictions it was asked to make.

Their program learned how to predict cell function in different scenarios and settings from annotated images of cells. It soon could rapidly analyze images of the lab-grown eye tissues to classify the tissues as good or bad. This discovery has raised optimism in the stem cell research space.

Drapeau explains why this is so exciting;

When we talk about stem cells in general, we say stem cells as if they were all one thing, but there are many different types of stem cells.For example, hair follicle and dental pulp stem cells contain neuronal markers and can easily transform into neurons to repair the brain. Furthermore, the tissue undergoing repair must signal to attract stem cells and must secrete compounds to stimulate stem cell function. A complex analysis of the tissue that needs repair and the conditions of that tissue using AI, in any specific individual, will help select the right type of stem cells and the best cells in that stem cell population, along with the accompanying treatment to optimize stem cell-based tissue repair.

Christian Drapeau

Ina study published in Februaryof this year inStem Cells, researchers from Tokyo Medical and Dental University (TMDU) reported that their AI system, called DeepACT, had successfully identified healthy, productive skin stem cells with the same accuracy that a human could. This discovery further strengthens Drapeaus argument on the potentials of AI in this field.

This experiment owes its success to AIs machine learning capabilities, but it is expected that Deep Learning can be beneficially introduced into regenerative medicine.There are many futuristic projections for these possibilities, but many of them are not as far-fetched as they may first seem.

Researchers believe that AI can help fast-track the translation of regenerative medicine into clinical practice; the technology can be used to predict cell behavior in different environments. Therefore, hypothetically, it can be used to simulate the human environment. This means that researchers can gain in-depth information more rapidly.

Perhaps the most daring expectation is the possibility of using AI to pioneer the 3D printing of organs. In a world where organ shortage is a harsh reality, this would certainly come in handy. AI algorithms can be utilized to identify the best materials for artificial organs, understand the anatomic challenges during treatment, and design the organ.

Can stem cells actually be used along with other biological materials to grow functional 3D-printed organs? If this is possible, then pacemakers will soon give way to 3D-printed hearts. A 3D-printedheart valvehas already become a reality in India, making this even more of an imminent possibility.

While all of these possibilities excite Drapeau, he is confident that AIs capabilities with data analysis and prediction, which is already largely in use, would go down as its most beneficial contribution to stem cell research;

It was already shown that stem cells laid on the connective tissue of the heart, the soft skeleton of the heart, can lead the entire formation of a new heart. Stem cells have this enormous regenerative potential. AI can take this to another level by helping establish the conditions in which this type of regeneration can be orchestrated inside the body.But we have to be grateful for what we already have, over the last 20 years, I have studied endogenous stem cell mobilization and today the fact that we have such amazing results with Stemregen is testament that regenerative medicine is already a success.

As AI continues to scale over industry boundaries, we can only sit back and hope it delivers on its full potential promise. Who knows? Perhaps AI really can change the world.

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How The Overlap Between Artificial Intelligence And Stem Cell Research Is Producing Exciting Results - Forbes

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Although stem cells are known to work wonders, there is still a lot of misunderstanding about what they are, what they do, and how they work.

The good news is that StemCells21 can clear everything up for you. SC21 produces all of its cellular medications in-house, and all of its treatments are performed at its cutting-edge medical centre in Bangkok. Its a one-stop shop that adheres to high-quality standards.

This company will be on display at the Thailand International Boat Show, which will be hosted at Royal Phuket Marina from January 6 to 9 next year. Staff from StemCells21 will be on hand to walk you through the producers, pricing, and techniques.

StemCells21s laboratory is a full-scale culture & analysis laboratory specialising in the production & treatment of Mesenchymal Stem Cells (StemCells21), and Natural Killer Cells (ImmuneCells21). It has also launched a new generation of regenerative medicine called Pluripotent Stem Cells (iPSC21), which hold great potential for impacting chronic diseases in the quest for anti-ageing.

The lab has seven scientists & stem cell researchers, a couple of who have worked with Professor Shinya Yamanaka, who was awarded the Nobel Prize in Physiology or Medicine in 2012 for the discovery that mature cells can be reprogrammed to become pluripotent (iPS cells).

Photo Via: Stemcells 21

Before StemCells21 was created, Managing Director Paul Collier and co-founder Sergei Dmitrievs experienced the power of stem cells either first hand or through the treatment of someone close to them. They knew that stem cells could deliver positive health results, and also knew stem cell treatmentsand the clinics that administered themhad room for improvement.

After deep laboratory investigation, they came to see that most clinics utilised relatively low-quality stem cells and incomplete treatments. While these clinics could deliver a certain level of positive results, they were only scratching the surface of the promise that stem cell treatments could deliver.

Furthermore, the clinics themselves frequently provided a less-than-ideal patient experience. Clinics were generally hectic, unprofessional, and unwelcoming. Patients were often administered a single treatment and sent on their way, unsure if they had experienced an efficacious treatment or if they had travelled and paid for nothing.

StemCells21 was created to offer superior results and give you a welcoming experience. It was set up to provide the global community with access to treatments that few people are aware of, and to offer health benefits that are superior to what most people ever imagined were possible.

The SC21 complex in Bangkok houses the StemCells21, ImmuneCells21, and IPS21 laboratories, as well as the premium 5* IntelliHealth+ (IH+) Clinic.

IntelliHealth+ is a state-of-the-art medical centre licensed by the Thai medical authorities. The luxurious design, efficient workflow layouts, and modern treatments make it the ideal choice for customers seeking a premium level of healthcare in 5* settings.

The centre treats patients from all over the world and has staff who speak fluent English, Arabic, Chinese, Russian, Thai and Spanish.

Furthermore, SC21s come from all corners of the globe for these cutting edge treatments. Many VIPs travel to the clinic including presidents, prime ministers, sports stars, football managers, bank owners and heads of major corporations, many of whom return every six to twelve months and have been doing so for years.

Recently, SC21 treated a ten-year-old British boy who had Ewing sarcoma develop in his arm, which then spread to other areas. He had tried every treatment option in the UK. His trip and treatment were sponsored by UK football teams and the public. Since he started treatment hes put on weight, hes vibrant, and his demeanour has totally changed. Various tests and scans have shown he is responding very well to the immunotherapy course and will perform another round in a few months time.

SC21 focuses on three main areas: anti-ageing and longevity; orthopaedic and muscular-skeletal issues (knee, hip, back & shoulder); and chronic diseases (diabetes, liver cirrhosis, lung, respiratory, hearing & vision disorders). Aside from that, the clinic can also help with chronic fatigue and burn-out syndrome.

Outpatient services for anti-ageing, immunotherapy and regenerative medicine are available at the centre. The anti-ageing clinic has a cutting-edge approach to skin rejuvenation, dermatology, detoxification, and wellbeing. A youthful appearance, more energy, improved mental capacity and mobility, reduced aches and pains, and a stronger immune system are among the benefits.

Photo Via: Stemcells 21

The high level of traditional medicine and the unique protocols designed by the IH+ teams give patients real therapeutic benefits and longevity.

According to Paul Collier, a client typically receives two sessions of stem cell injections during a treatment intravenous for systemic and local to the target and is required to stay in Bangkok for two days following their procedure to monitor any complications that may arise. Then theyre given a two-month take-home kit that comprises self-administered injections (similar to insulin) that target specific growth factors in organs or tissues that need to be repaired. These can also be taken orally, but they are less effective.

He goes on to say that stem cells are the foundation of the human body. They split over and over to produce humans from an embryo at the start of our lives. They restore cells in your blood, bone, skin, and organs throughout your life to keep you alive and functioning. Stem cells have two distinct properties that distinguish them from other types of cells in our bodies.

First, they can self-renew (mitosis), which is a stage of the cell cycle in which replicated chromosomes are divided into two new nuclei. As a result, identical duplicated cells are produced.

Secondly, they have the ability to differentiate into specialized cells such as cartilage, heart cells, liver cells, and neurons. No other cell in the body has the natural ability to generate new cell types.

Mesenchymal Stem Cells (MSCs) are at the core of StemCells21s regenerative programs. They are multipotent stem cells derived from various adult and fetal tissues. A large number of studies have shown the beneficial effects of MSC-based therapies to treat different pathologies, including neurological disorders, cardiac ischemia, diabetes, and bone and cartilage diseases.

StemCells21 also has arthritis treatment, which reduces inflammation & joint pain, increases cartilage growth, improves mobility & joint stability and lessens dependence on medication. The clinics degenerative spine treatments help discs regenerate and stabilize the spine.

On top of that, it provides lung & liver disease treatment as well as treatments for autism, cerebral palsy, diabetes, motor neuron disease, multiple sclerosis and immune disorders.

Theres even eye treatment, which reduces blurred vision & field of vision defects, improves night vision & enhances colour texture.

Photo Via: Stemcells 21

SC21 can even help with certain types of cancer by taking a clients blood and growing their natural killer cells (immunotherapy) over a 21-day period. Through various stimuli, their cytotoxicity is increased which kills cancer and virally-affected cells.

Paul says stem cell therapy should be looked at before undergoing any kind of invasive surgery. The type of medicine should certainly be an intervention before surgery. If you are looking at knee replacement, why not consider an injection of a biologic that would only take a couple of days and has the potential to remodel the cartilage, because once you perform surgery there is no going back.

SC21 also produces a wide range of stem-cell extract-based cosmetics and nutritional supplements, which are available at their medical centres and online under the brand SC21 Biotech.

The Thailand International Boat Show will feature Paul Collier and his team. Theyll be able to answer any of your questions about the cost, procedure, and treatment. On top of that, they will also assist you in educating yourself and managing your expectations so that you do not expect more than stem cell therapy can provide. If you want to get treatment, they will also provide you with a complete report on all treatments. SC21 is fully compliant with international regulations and guidelines.

http://www.stemcells21.com http://www.intellihealthplus.com

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SC21- 21st century cellular medicines specialists - The Thaiger

NEW YORK, Nov. 21, 2021 (GLOBE NEWSWIRE) -- Mesoblast Limited (Nasdaq:MESO; ASX:MSB), global leader in allogeneic cellular medicines for inflammatory diseases, today announced that it has successfully refinanced its existing senior debt facility with a new US$90 million five year facility provided by funds managed by Oaktree Capital Management, L.P. (“Oaktree”).

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Mesoblast and Oaktree Capital Enter Into Refinancing and Expansion of Senior Debt Facility

UW Health treats first patient in U.S. with investigational cell therapy for heart disease

Appleton resident Donald Krause became the first patient in the country last week to undergo an investigational cell therapy for a debilitating heart condition called chronic myocardial ischemia (CMI). Krause was treated by Amish Raval, MD, an interventional cardiologist at UW Health, supported by Peiman Hematti, MD, a bone marrow transplantation hematologist at the UW School of Medicine and Public Health.

October 29, 2021SMPH News

Center members Dr. Anita Bhattacharyy and Dr. Su-Chun Zhang, in collaboration with Waisman and the University of Washington-Seattle and Seattle Childrens Hospital, have been awarded an $11 million Transformative Research grant from the National Institutes of Health to create a new approach using stem cells that may reveal how brain development in individuals with Down syndrome differs from typically developing individuals, identify features that will help understand their intellectual disability, and find potential targets for therapy. They will also address questions that remain unanswered about brain development overall.

October 7th, 2021UW News

The U.S. Food and Drug Administration on Tuesday approved StrataGraft, a topical treatment for severe burns made from skin tissue, providing a boost for Madison-based firm Stratatech. Stratatech was founded in 2000 by SCRMC member Lynn Allen-Hoffman, the first female University of Wisconsin-Madison faculty member to start a biotech company.

June 16, 2021The Cap Times

The Food and Drug Administration-approved trial will use a form of transplant that replaces a patients bone marrow with alpha-beta T-cell depleted peripheral blood stem cells from closely matched unrelated donors or family members.

May 27, 2021

Over the past two decades, stem cell research at UW-Madison has grown from involving a handful of scientists to nearly 100 from more than 30 schools, colleges and departments.

May 25, 2021Quarterly Magazine, Vol. 23, No. 1

Nine University of WisconsinMadison postdoctoral researchers have been recognized with the inaugural Postdoc Excellence Awards for their teaching, service and mentoring. Daniel Z. Radecki (Comparative Biosciences) received one of these awards.

The defining feature of Dans work with the (UWMadison Postdoctoral Association) and others is his commitment to bettering the lives of all postdocs. He envisions how each event and initiative can best impact the individual, through the lenses of diversity and inclusion, immigration status, postdocs personal lives (e.g. childcare considerations), department/discipline, and more.

Congratulations, Daniel!

April 29, 2021

Researchers at UWMadison have made new photoreceptors from human pluripotent stem cells. However, it remains challenging to precisely deliver those photoreceptors within the diseased or damaged eye so that they can form appropriate connections, says David Gamm, director of the McPherson Eye Research Institute and professor of ophthalmology and visual sciences at the UW School of Medicine and Public Health.

While it was a breakthrough to be able to make the spare parts these photoreceptors its still necessary to get them to the right spot so they can effectively reconstruct the retina, he says. So, we started thinking, How can we deliver these cells in a more intelligent way? Thats when we reached out to our world-class engineers at UWMadison.

Research from the University of WisconsinMadison finds that a new therapeutic approach for heart failure could help restore cardiac function by regenerating heart muscle. In a study recently published in the journal Circulation, the UW team describes its success in improving, in a mouse model, the function of heart muscle by temporarily blocking a key metabolic enzyme after a heart attack. This simple intervention, the researchers say, could ultimately help people regain cardiac function. Our goal was to gain new understanding of how the heart can heal itself following injury at the molecular and cellular level and see if there was a way to restore cardiac function to an earlier state, says UWMadisons Ahmed Mahmoud, professor of cell and regenerative biology in the School of Medicine and Public Health.

Learn more about the research here.April 15, 2021

Grafting neurons grown from monkeys own cells into their brains relieved the debilitating movement and depression symptoms associated with Parkinsons disease, researchers at the University of WisconsinMadison reported today. In a study published in the journal Nature Medicine the UW team describes its success with neurons made from cells from the monkeys own bodies after reprogramming to induced pluripotent stem cells. UWMadison neuroscientist Su-Chun Zhang, whose Waisman Center lab grew the brain cells, said this approach avoided complications with the primates immune systems and takes an important step toward a treatment for millions of human Parkinsons patients. Learn more about their work here.March 1, 2021

The project, led by David Gamm, MD, PhD, director of the McPherson Eye Research Institute and professor of ophthalmology and visual sciences at the UW School of Medicine and Public Health, will develop a transplantable patch to restore vision to members of the armed forces who have been injured by blasts or lasers.December 11, 2020

This week, the NIH Office of Research Infrastructure Programs highlights Dr. Marina Emborg, her WNPRC lab team and their UWMadison colleagues advances in detecting heart disease in Parkinsons and evaluating new therapies that specifically target nerve disease within the human heart.December 2020

Its been 25 years since University of WisconsinMadison scientist James Thomson became the first in the world to successfully isolate and culture primate embryonic stem cells. He accomplished this breakthrough first with nonhuman primates at the Wisconsin National Primate Research Center in 1995, using rhesus monkey cells, then in 1996 with marmoset cells. Thomson then published his world-changing breakthrough on human embryonic stem cell derivation in Science on Nov. 6, 1998.November 6, 2020

EEMs and exosomes each have attractive characteristics as therapeutics, Dr. Hematti, UW-Madisons Department of Medicine, noted. As a cell therapy, EEMs will not proliferate or differentiate to undesirable cell types, which remains a concern for many stem cell therapies. Moreover, EEMs could be generated from a patients own monocytes using off-the-shelf exosomes, resulting in a faster and more facile process compared to autologous MSCs. Alternatively, exosome therapy could be a cell free, shelf-stable therapeutic to deliver biologically active components. Altogether, we believe our studies results support the use of EEMs and/or exosomes to improve ligament healing by modulating inflammation and tissue remodeling, Dr. Vanderby concluded.November 3, 2020

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Our Need For Things Lab-Grown

What was once something of the movies objects forming themselves in thin air is real now. Various things can be grown in a laboratory setting, some even on a large scale for commercial distribution. This technology could be a big part of the solution to establish sustainable societies. At the moment, we harvest organs from the deceased, rear animals for meat and dairy, destroy forests by cutting down trees for wood, mine the earth for diamonds, and the list goes on. All these things can already be lab-made or are on the brink of reality.

Once these staples of society can be mass-made affordably, they could supply the world while minimally impacting the natural environment. Acres of land wouldnt need to be used for food and building materials, meaning deforestation can cease, for starters. Looking at lab-grown meats alone: they require 99% less land than traditionally farmed meats, generate up to 96% fewer emissions, use up to 96% less water, and no animals need to be slaughtered in the process.

Naturally, there will be short-term disruptions, particularly job-related. For example, eco-friendly agriculture will mean fewer farms and agriculture jobs. But new employment opportunities will emerge in the scientific and technical fields related to lab-grown foods.

Whats the difference between 3D printing (additive manufacturing) and lab-grown, you may be wondering? 3D printing uses material as ink anything from plastic to cellular material whereas lab-grown materials start off as a bit of material that multiplies on its own, replicating natural processes. Thus, lab-grown material has the same cellular structure as the naturally occurring material and mimics the natural formation process but within a much shorter period.

In the future, we are bound to see various lab-grown breakthroughs coming from the medical field. Eventually, there should be alternative sources for organs and blood cultured from stem cells. In addition, there will likely be lab-produced medicines (lotions, ointments, balms, nutraceuticals, energy drinks, etc.), breast milk, and more.

Scientists are well on the way to functioning full-sized organs, with several innovations in fully functional mini-organs, or organoids, making headlines in recent years. For now, these organoids are tools for testing new drugs and studying human diseases. But soon enough, these research teams will take the technology to the next level and develop organs that can be used for implantation when someone needs an organ replacement. So far, the brain, liver, lungs, thymus, heart, blood, and blood vessels are among the growing list of lab-grown medical accomplishments.

A team of scientists from the University of Pittsburgh managed to grow miniature human livers using induced pluripotent stem cells (IPSCs) made from human skin cells. Meaning, in the far future, someone needing a liver transplant could have the organ grown from their own skin cells! This method may even reduce the chances of a patients immune system rejecting the new tissue because it would recognize the cells as self. Whats more, their lab-grown livers matured in under a month compared to two years in a natural environment.

The scientists tested their fully-functional mini-livers by transplanting them into rats. In this proof-of-concept study, the lab-made organs survived for four days inside their animal hosts, secreting bile acids and urea like a healthy liver would.

A research team led by the University Hospital Dsseldorf induced pluripotent stem cells (iPSCs) to grow into pea-sized brain organoids with rudimentary eye structures that sense light and send signals to the rest of the brain. They used skin cells taken from adult donors, reverted them back into stem cells, and placed them into a culture mimicking a developing brains environment, which encourages them to form specific brain cells. Their mini-brains grew optic cups, vision structures of the eye found where the optic nerve and retina meet. The cups even grew symmetrically, as eyes would, and were functional!

Jay Gopalakrishnan, a senior author of the study, said:

Our work highlights the remarkable ability of brain organoids to generate primitive sensory structures that are light sensitive and harbor cell types similar to those found in the body. These organoids can help to study brain-eye interactions during embryo development, model congenital retinal disorders, and generate patient-specific retinal cell types for personalized drug testing and transplantation therapies.

This achievement is the first time an in vitro system shows nerve fibers of retinal ganglion cells reaching out to connect with their brain target an essential aspect of the mammalian brain.

Scientists from Michigan State University developed functional miniature human heart models grown from stem cells complete with all primary heart cell types and with functioning chambers and vascular tissue. The models could help researchers better understand how hearts develop and provide an ethical platform for treating disease and testing drugs or new treatments.

The teams lab-grown mini hearts follow the fetal development of a human heart, offering a new view into that process. The organoids start beating by day six, and they grow into spheres approximately 1 mm (0.4 in) wide, with all significant cardiac cell types and multiple internal chambers by day 15.

Aside from research purposes, full-sized lab-grown hearts could solve the shortage problem of hearts the world faces today. More than 25 million people suffer heart failure each year. In the United States, approximately 2,500 of the 4,000 people in line for heart transplants receive them. That means almost 50% of the people needing a new heart to keep them alive wont get it.

Unlimited supplies of blood for transfusions are possible with lab-growing technology. Blood has been challenging to grow in the lab. However, real breakthroughs in creating artificial blood have sprung up!

A couple of years ago, Japanese researchers developed universal artificial blood that worked for all blood types. It even has a shelf life of one year stored at room temperature, therefore eliminating the problem of identifying blood type and storage simultaneously.

Like that wasnt impressive enough, last year, a team of scientists from the South China University of Technology, the University of New Mexico, and Sandia National Laboratories created artificial red blood cells (RBCs) with more potential capabilities than real ones! The synthetic RBCs mimic the properties of natural ones such as oxygen transport, flexibility, and long circulation times with the addition of a few new tricks up their sleeves, such as toxin detection, magnetic targeting, and therapeutic drug delivery. In addition, blood contains platelets and red blood cells, so these new cells could be used to make superior artificial blood.

Researchers from the University of British Columbia successfully coaxed stem cells to grow into human blood vessels. The thing that is so remarkable about this study is that the system of blood vessels grown in the lab is virtually identical to the ones currently transporting blood throughout the body. They are using this now to generate new leads in diabetes treatment. They put the lab-grown blood vessels in a petri dish designed to mimic a diabetic environment.

The global demand for meat and dairy is expected to rise by almost 90% over the next 30 years, regardless of the need to cut back on meat consumption. The risk of environmental damage and the rising food demand itself is a problem many have recently addressed. Thats why companies worldwide are on the verge of scaling up all sorts of lab processes to produce various food items, including steaks, chicken, cheese, milk, ice cream, fruits, and more.

Thinktank RethinkX even published research suggesting that proteins from precision fermentation (lab-grown protein using microbes) will be about ten times cheaper than animal protein by 2035, resulting in a collapse of the livestock industry. It says the new food economy will subsequently:

replace an extravagantly inefficient system that requires enormous quantities of inputs and produces considerable amounts of waste with one that is precise, targeted, and tractable. [Using tiny land areas, with a massively reduced requirement for water and nutrients, it] presents the most significant opportunity for environmental restoration in human historyFarm-free food offers hope where hope is missing. We will soon be able to feed the world without devouring it.

The worlds pace of meat consumption is placing a significant strain on the environment. Many studies show that eating less meat is just as crucial to slowing down global warming as using solar panels and zero-emissions vehicles. Unfortunately, animal farming generates an obscene amount of greenhouse gas emissions. Yet again, scientists come to the rescue, working diligently to fix this situation.

Over a decade ago, researchers created something akin to ground beef, but the complex structure of steak didnt happen until recently, with Aleph Farms debuting its thick-cut rib-eye steak in 2018. Furthermore, that first burger cost around US$345,000, but now the price has dropped dramatically to the point that lab-grown chicken is to be commercially produced and hit grocery store shelves as of this year.

SuperMeat, Eat Just, and Aleph Farms are todays most prominent startups working on getting lab-grown meats to people looking to lower their carbon and environmental footprints. In addition, their products are made from actual animal cells, so theyre real meat, but no animals had to be hurt or killed.

Speaking of Aleph Farms, the company also grew meat in space to show that it can even be done in a zero-gravity environment with limited resources.

Aside from Aleph Farms figuring out how to make steak like an authentic steak, a group of Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) researchers also devised a solution to the texture challenge. First, they made edible gelatin scaffolds that have the texture and consistency of real meat. Then, they grew rabbit and cow muscle cells on this scaffolding. The research demonstrates how realistic meat products are possible!

Parker and his Disease Biophysics Group developed a technique to produce the scaffolding. Its a fiber-production system inspired by cotton candy known as immersion Rotary Jet-Spinning (iRJS). It enabled the team to spin long nanofibers of a specific shape and size using centrifugal force. So, they spun food-safe gelatin fibers, creating the base upon which cells could grow.

Natural muscle tissue is composed of an extracellular matrix, which is the glue that holds the tissue together. As a result, it contributes to the texture of the meat. The spun gelatin fibers mimicked this extracellular matrix and provided the texture to make the lab-grown meat realistic. When the team seeded the fibers with animal (rabbit and cow) muscle cells, they anchored to the gelatin scaffolding and grew in long, thin structures, similar to real meat.

Meanwhile, Boston College developed a new, even greener technology that uses the skeleton of spinach leaves to support bovine animal protein growth. However, animal products arent eliminated from the process entirely. For example, lab-grown steak and chicken are created by painlessly harvesting muscle cells from a living cow, subsequently fed and nurtured to multiply and develop muscle tissue. But for this to have the same texture as real meat, the cells need structural support to flourish and are therefore placed in a scaffold.

Singapore is leading the way, becoming the first country in the world to approve the sale of Eat Justs cultured chicken. The company will start by selling nuggets at a restaurant. Meanwhile, SuperMeat has been handing out lab-grown chicken burgers in Israel for free. Theyre aiming to gain public acceptance of the idea.

The cultured chicken starts as a tiny number of harvested cells. Those cells are put into a bioreactor and fed the same nutrients the living animal would consume to grow. The cells multiply and turn into an edible portion of cultured chicken meat. The meats composition is identical to that of real chicken and offers the same nutritional value. And its cleaner because its antibiotic-free!

Labs are manufacturing dairy products by utilizing the fermentation process of living microbes to produce dairy proteins like whey and casein. These proteins are then used to make dairy products like butter, cheese, and ice cream. Two leading companies in this category are Imagindairy and Perfect Day, which already have several products on supermarket shelves in the United States.

Researchers havent figured out how to make fruits and vegetables yet, but a team is perfecting a cell cultivation process that generates plant biomass. The stuff tastes like the natural-grown product from which the cells were obtained and even exceeded its nutritional properties. Although, the texture of the biomass is different. For example, an apple isnt a solid apple akin to one grown from a tree. Instead, its like applesauce.

Lab-produced materials Including wood, diamonds, leather, glass, clothing, crystals, gels, cardboard, and plastics for making objects are either under development or already available. Many materials need to be taken from nature mined from the earth or cut down from forests. If they can be made in a lab instead, then people could leave nature alone!

A recent project led by a Ph.D. student at MIT paves the way for lab-grown wood one of the worlds most vital resources used to make paper, build houses, heat buildings, and so much more. The process begins with live plant cells cultivated in a growth medium coaxed using plant hormones to become wood-like structures. Next, a gel matrix is used to guide the shape of the cellular growth, and controlling the levels of plant hormones regulates the structural characteristics. Therefore, the technology could grow anything from tables and chairs to doors to boats and so on.

The environmental and socio-economic impact of traditionally mined diamonds has been exposed in recent years, and as awareness grows, the rising popularity of lab-grown diamonds does too. Mined diamonds are linked to bloody conflicts, and their excavation produces carbon emissions, requires substantial water use, and causes severe land disturbances.

Research has found that 1,000 tons of earth have to be shifted, 3,890 liters or more of water is used, and 108kg of carbon is emitted per one-carat stone produced. In addition, the traditional diamond mining industry causes irreversible damage to the environment, hence why, a decade ago, researchers started experimenting with how to grow them in the lab. Its been a feat a long time in the making, but we finally have lab-grown diamonds available for eco-conscious consumers to buy.

Diamonds are made of pure carbon. It takes extreme heat and pressure for carbon to crystalize. In nature, this happens hundreds of miles beneath the Earths surface. The ones being mined were shot out by a volcano millions of years ago. So how have scientists managed to hack such an intense and time-consuming process?

They began by investigating the mechanisms behind the diamond formation, zooming in at the atomic level. This led to the invention of a novel technology that utilizes the process of HPHT (high pressure, high temperature) to mimic the natural atmospheric conditions of diamond formation. Labs can use it to replicate the process and turn pure carbon into diamonds in 2-6 weeks.

Lab-grown gems are eco-friendly rocks, especially when theyre made entirely from the sky, like SkyDiamonds. Even the electricity used to grow its stones is from renewables, so theyll indeed be the worlds first zero-impact diamonds.

But how are the diamonds created out of thin air? They are made of carbon from the sky and rainwater. The sky mining facility is in Stroud. Energy is sourced from wind and sunlight. The CO2 is sourced directly from the air. Hydrogen is produced by splitting rainwater molecules in an electrolysis machine using renewable energy. The captured carbon and hydrogen are then used to make methane, used to grow the diamonds. The final product is a diamond anatomically identical to those mined from the ground. It is even accredited, fully certified, and graded by the International Gemological Institute.

Another company, Climeworks, is also making diamonds using carbon sucked from the sky. However, SkyDiamonds takes it a step forward by using rainwater and sunshine in the process.

The last lab-grown object were going to discuss is not something in the works, but an idea a fantastic and outlandish one thats jumping far into the future but was thought up in 2010 by Mercedes Benz. The luxury car companys ambitious BIOME idea shows just how wild imagination can get with lab-grown technology. It envisions a day when it can grow an entire supercar from scratch.

Mercedes-Benz explained when launching the concept:

The interior of the BIOME grows from the DNA in the Mercedes star on the front of the vehicle, while the exterior grows from the star on the rear. The Mercedes star is genetically engineered in each case to accommodate specific customer requirements, and the vehicle grows when the genetic code is combined with the seed capsule. The wheels are grown from four separate seeds.

This list of lab-grown possibilities is just the tip of the iceberg! Other materials in the pipeline include leather, chocolate, and silk. This intelligent technology can make anything a scientist can dream up! The only limit is the imagination and dedication of brilliant people.

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Lab-Growing Everything Might Be The Only Way To Attain A Sustainable World - Intelligent Living

Phovia is highly effective for treating superficial and deep skin infections.

This article is sponsored by Vetoquinol.

Superficial bacterial folliculitis, also called superficial pyoderma, is a commonly diagnosed dermatological condition in dogs.1,2 These infections are secondary to primary conditions affecting normal skin barrier function (eg, allergic skin disease, trauma, burns), keratinization (eg, nutritional deficiency, liver disease), and immune regulation (eg, neoplasia, autoimmunity, endocrinopathy).2 Cats less commonly develop superficial pyoderma perhaps because of decreased adhesion of staphylococci to feline corneocytes, but the primary issues causing infection are similar to those seen in dogs.3-8

The primary pathogen associated with superficial pyoderma in dogs and cats is a normal resident of the skin, Staphylococcus pseudintermedius, but other flora may be involved.2,8-12 As the normal homeostasis of this organism is disrupted from a primary disease, these gram-positive cocci invade deeper regions of the epidermis and hair follicle epithelium, increase in number, and enhance inflammation.

Classical clinical lesions of superficial pyoderma include papules and pustules that may eventually progress to alopecia, epidermal collarettes, scales, and crusts. Often the skin is erythematous and pruritic. Chronic cases may demonstrate lichenification, hyperpigmentation, and scarring alopecia from long-standing inflammation and infection.2 Cats may develop even more unique cutaneous reaction patterns and skin lesionsespecially when allergic skin disease is presentincluding miliary dermatitis, eosinophilic plaques, rodent ulcers, and eosinophilic granulomas.5

Identifying and addressing the primary disease is paramount in achieving complete, permanent resolution of the superficial pyoderma. Therefore, treatment is multifactorial and aimed at addressing the primary disease, reducing skin inflammation, and treating the infection directly. Current guidelines for the treatment of superficial pyoderma in dogs recommend the use of topical antimicrobials as sole therapy whenever possible; however, overuse of systemic antibiotics remains common.2,13-16

Topical therapy has many benefits including direct antimicrobial effects without use of an antibiotic, reduction in antibiotic-resistant bacterial populations, restoration of the normal skin barrier, enhancement of skin hydration, physical removal of keratinous debris, and removal of offending allergens from the haircoat.2,14 However, topical therapy is met with challenges that impede clinical application. Adherence is the biggest concern when recommending topical therapy to pet owners. Frequent bathing or application of medicated solutions to the skin can be difficult when busy owner lifestyles combine with a nonadherent patient. Skin inflammation can be painful and animals may be resistant to topical therapy. Cats are fastidious groomers and may lick away a medicated topical therapy before it can achieve appropriate contact time. Additionally, some topical agents can cause oral erosions and ulcerations or even gastrointestinal disturbance when groomed off. For these reasons, systemic antibiotics continue to be a common prescribing practice for superficial pyoderma.

All antibiotic use, despite duration or frequency, contributes to the development of antibiotic-resistant bacterial populations on the animal and in the environment.17-19 From that very first dose, bacteria are constantly evolving to implement inherent and acquired resistance mechanisms necessary for survival. One well-recognized mechanism is oxacillin resistance through the mecA gene, which produces a penicillin-binding protein receptor with poor affinity for -lactam antibiotics.2,14,15,20-23 Even more concerning than these oxacillin-resistant strains are those that develop multidrug resistance, which is defined as resistance to 3 or more antibiotic drug classes. This may happen over time with repeated antibiotic exposure or after a single dose of certain antibiotics such as fluorinated quinolones.2,20,23-25 The continued emergence of antibiotic-resistant bacteria inhibits the successful treatment of bacterial infections in pets and humans. As veterinarians consider how their antibiotic use contributes to this growing pandemic, they must look for alternative, safe, effective, affordable, and convenient antibacterial treatment modalities.

Phovia as a solution

Investigation into the photobiological effects of light therapy has been ongoing for the past 50 years. Photobiomodulation (PBM) therapy is a type of light treatment that uses visible or near infrared light to promote therapeutic benefits including induction of tissue healing and regeneration and inhibition of biological responses that induce pain or inflammation. The treatment distance, wavelength, fluence, pulse parameters, spot size, and irradiation time influence the effects of light energy on tissue. Visible light with wavelengths ranging from 400 to 700 nm can stimulate positive photobiomodulatory effects that promote wound healing, reduce inflammation and pain, modulate stem cell populations, and reduce bacterial contamination of wounds.26,27

Once visible light enters the skin, it is absorbed by the cells and initiates chemical changes dependent on the wavelength (or color) of light and the chromophore within the skin.27 Within each cell, membrane-bound organelles called mitochondria contain chromophores that absorb the light energy and begin making energy (adenosine triphosphate; ATP) via activation of cytochrome c oxidase. Outcomes of the mitochondrial respiratory pathway activation include stimulation of secondary messenger pathways, production of transcription factors and growth factors, and increased ATP production. However, excessive light energy exposure will overstimulate mitochondrial respiration and cause expenditure of all ATP reserves, which creates oxidative stress resulting in damaging elevations of nitric oxide, production of harmful free radicals, and activation of cytotoxic mitochondrial-signaling pathways leading to apoptosis.27,28 This is why creating PBM therapy protocols is important for targeting the beneficial effects while avoiding unintended harm.

Specific benefits of light energy within the visible light spectrum can be broken down into each color of light. Blue light (400-500 nm) has a lower penetration depth and primarily interacts with keratinocytes, reduces bacterial adhesion and growth, and increases intracellular calcium and osteoblast differentiation.29-31 Green light (495-570 nm) affects the superficial tissue and alters melanogenesis, reduces hyperpigmentation of the skin, and reduces tissue swelling.29,30 Red light (600-750 nm) penetrates deeper into the dermis and subcutis where it acts on cellular mitochondria to reduce inflammation and promote collagen synthesis through fibroblast proliferation and production of transforming growth factor-, fibroblast growth factor, platelet derived growth factor, and others.26-28,32,33 Red light has proliferative effects on mesenchymal stem cells and induces proliferation of epithelial colony forming units important for tissue repair and regeneration.34,35

Phovia, sold by Vetoquinol, is a form of fluorescent PBM therapy utilizing a blue light emitting diode (LED lamp, 400-460 nm) and topical photoconverter gel that emits low-energy fluorescent light (510-600 nm) when illuminated by the LED lamp.36,37 This interaction results in the formation of multiple wavelengths of visible light, each with a unique depth of penetration and effect on the tissue as described above. Application is fast and simple. The affected skin may be clipped free of hair and cellular debris removed with gentle cleaning. The skin is allowed to dry before application of the photoconverter gel. Just prior to application, 1 ampule of fluorescence chromophore gel is added to 1 container of photoconverter carrier gel and mixed thoroughly. The mixture is applied in a 2-mm layer to the affected skin, and the LED lamp is held 5 cm above the lesion and used to illuminate the area for 2 minutes. The gel is wiped away using saline-soaked gauze. The application can be repeated immediately after 5 to 10 minutes of rest or a second application can occur a few days later. Twice-weekly applications are continued until the wound is healed. Appropriate eyewear is required to protect the operator from the intensely bright light. Application is pain free and stress free for the patient, so sedation is not typically required.

Benefits of Phovia

Phovia shows great promise as a safe, effective therapy for treatment of numerous inflammatory dermatoses in dogs including superficial pyoderma,38 deep pyoderma,39 perianal fistula,40 interdigital dermatitis,41 calcinosis cutis,42 acute traumatic wounds,43 chronic wounds,37 surgical wounds,44 and otitis externa.45 Phovia as a sole therapy speeds time to healing by 36% in canine superficial pyoderma as compared with dogs receiving oral antibiotics alone.38 In one study, dogs with superficial pyoderma were treated with Phovia alone or with an oral antibiotic alone. Dogs treated twice weekly with Phovia demonstrated complete clinical healing in about 2.3 weeks (P < .05)whereas dogs receiving oral antibiotic healed in about 3.75 weeks.38 Additionally, Phovia speeds time to healing by nearly 50% in deep pyoderma when used with an oral antibiotic (5.7 weeks of treatment) compared with dogs receiving only oral antibiotic (11.7 weeks of treatment).39 The ability of this fluorescent PBM therapy to eliminate or significantly reduce duration of exposure to antibiotics will decrease the spread of antibiotic-resistant bacterial strains within pets and humans.

Phovias high safety profile makes it a beneficial tool to implement in everyday practice. Training the veterinary team to communicate therapy benefits with clients as well as to perform treatments is fast and easy. Training the veterinary technicians to perform treatments will give the veterinarian time to examine other patients. A single back-to-back application takes about 15 minutes, so pet owners can be in and out of the clinic quickly; however, the 2 weekly treatments can be separated by a few days if the veterinarian prefers to evaluate the patient more frequently. Additionally, when used as a sole therapy, clients are not required to administer oral or topical medications at home. This greatly improves treatment adherence and success. Instruct clients to use once-daily smartphone photos to document improvement at home. This can be useful when deciding how many treatments to perform. Most cases of superficial pyoderma will resolve completely by the third treatment.38 It is a good idea to communicate to clients that 3 to 4 weekly treatments may be required.

Conclusion

Phovia is a versatile, innovative therapeutic approach to numerous types of dermatitis.36 It is easy to implement in general practice, and is safe, pain free, and affordable. Phovia is highly effective for superficial and deep skin infections and eliminates the need for clients to administer numerous at-home treatments. This greatly improves the pet-owner bond and treatment outcomes by promoting adherence. Phovia accelerates time to wound healing, which decreases duration of antibiotic exposure and may reduce risk of antibiotic resistance development in these cases.2,13,36-39 Phovias efficacy against antibiotic-susceptible and antibiotic-resistant bacteria shows promise as an alternative therapeutic approach that promotes the principles of antimicrobial stewardship.36 If you are interested in purchasing this medical device for your practice, contact your Vetoquinol service representative.

Amelia G. White, DVM, MS, DACVD is an associate clinical professor of dermatology at Auburn University College of Veterinary Medicine.

REFERENCES

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Managing superficial pyoderma with light therapy - DVM 360

image:Dr. Ulrich G. Steidl view more

Credit: Albert Einstein College of Medicine

October 27, 2021(BRONX, NY)Ulrich G. Steidl, M.D., Ph.D., co-director of the Blood Cancer Institute and associate director of basic science at the Albert Einstein Cancer Center (AECC), has received a prestigious Outstanding Investigator Award from the National Cancer Institute (NCI). This award is accompanied by a seven-year, $7 million grant to study the molecular and cellular mechanisms that lead to two related blood diseases, myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML). Dr. Steidl is one of only 17 recipients of this award in 2021, which is given to accomplished leaders in cancer research who provide significant contributions in their field. The ultimate goal of this research is to develop new treatments and cures for these usually fatal disorders.

Clinical outcomes in MDS and AML have not significantly improved over the past half-century, and cure rates remain below 15% for most patients, said Dr. Steidl, who is also professor of cell biology and of medicine and the Diane and Arthur B. Belfer Faculty Scholar in Cancer Research at Einstein. There is an urgent need to improve our understanding of how these diseases develop and to devise more effective therapies.

MDS and AML Explained

MDS occurs when blood-forming (hematopoietic) stem cells in the bone marrow acquire genetic and non-genetic irregularities, leading to the production of abnormal, dysfunctional blood cells, which out-compete healthy cells. Common symptoms include anemia, infections, and bleeding.

The incidence of MDS in the United States is unclear, with estimates ranging from 10,000 to 40,000 new cases annually; about one-third of MDS patients will go on to develop AML. Treatment for MDS is generally limited to preventing or reducing complications, particularly severe anemia. The only cure is a bone-marrow transplanta therapy not easily tolerated and therefore often reserved for the youngest, most resilient patients. However, most people diagnosed with MDS are elderly.

AML, like MDS, begins with abnormal bone marrow stem cells. But in AML, those cells, after becoming cancerous, proliferate rapidly and quickly spread to the blood and other hematopoietic organs, such as the bone marrow and spleen, and sometimes to other tissues, causing many of the same symptoms seen in MDS, plus others. AML is often fatal within just a few months and afflicts about 21,000 Americans each year. It is usually treated with chemotherapy. Bone-marrow transplantation can cure AML in some patients.

From Stem Cells to Cancer

Recent studies led by Dr. Steidl and his research team have shown that both MDS and AML arise from pre-leukemic stems cells (pre-LSCs), a subpopulation of blood-forming stem cells that have genetic and non-genetic aberrations. Certain varieties (clones) of these pre-LSCs go on to develop into leukemic stem cells (LSCs)cancer cells that are capable of self-renewal. These LSCs lead to sustained leukemia growth and are particularly resistant to drugs. We now know that the considerable diversity of pre-LSC clones affects the development, progression, and treatment resistance of both MDS and AML, said Dr. Steidl, one of the nations leading authorities on both diseases.

What causes some pre-LSCs but not others to become leukemic is not clear, but transcription factors are thought to play a key role. Transcription factors are proteins that turn specific genes on or off, determining a cells function by regulating the activity of genes. In the case of stem cells, transcription factors guide their differentiation into mature cells. Our recent work has shown that the actions of key transcription factors are dysregulated in pre-LSCs and LSCs, meaning that the transcription factors and the molecular programs they govern behave abnormally, he added.

Thanks to his new NCI grant, Dr. Steidl hopes to:

To accomplish these goals, Dr. Steidls research team will employ novel tools for analyzing stem cell clones in patients, as well as newly developed mouse models of pre-LSC progression to MDS and AML.

Developing New Cancer Therapies

The knowledge we gain from this research should enable us to develop drugs that target pre-LSCs and their aberrant transcription factors, said Dr. Steidl. Such an approach holds the promise of achieving lasting remissions and, ultimately, even cures. Hopefully, our understanding of the early events in the progression of MDS and AML may even allow us in the future to prevent these diseases by interrupting the transformation of pre-LSCs to LSCs before overt leukemia can occur.

The grant (R35CA253127) is titled Molecular and Cellular Regulation of Pre-Leukemic Stem Cells and their Therapeutic Targeting.

***

About Albert Einstein College of Medicine

Albert Einstein College of Medicine is one of the nations premier centers for research, medical education and clinical investigation. During the 2020-21 academic year, Einstein is home to 721 M.D. students, 178 Ph.D. students, 109 students in the combined M.D./Ph.D. program, and 265 postdoctoral research fellows. The College of Medicine has more than 1,900 full-time faculty members located on the main campus and at its clinical affiliates. In 2020, Einstein received more than $197 million in awards from the National Institutes of Health (NIH). This includes the funding of major research centers at Einstein in aging, intellectual development disorders, diabetes, cancer, clinical and translational research, liver disease, and AIDS. Other areas where the College of Medicine is concentrating its efforts include developmental brain research, neuroscience, cardiac disease, and initiatives to reduce and eliminate ethnic and racial health disparities. Its partnership with Montefiore, the University Hospital and academic medical center for Einstein, advances clinical and translational research to accelerate the pace at which new discoveries become the treatments and therapies that benefit patients. Einstein runs one of the largest residency and fellowship training programs in the medical and dental professions in the United States through Montefiore and an affiliation network involving hospitals and medical centers in the Bronx, Brooklyn and on Long Island. For more information, please visit einsteinmed.org, read our blog, followus on Twitter, like us on Facebook, and view us on YouTube.

Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.

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Albert Einstein Cancer Center researcher receives NCI Outstanding Investigator Award to study two deadly blood diseases - EurekAlert

Curr Cardiol Rev. 2013 Feb; 9(1): 6372.

1Department of Medicine, University of Minnesota Medical School, Minneapolis, Minnesota, USA

2Stem Cell Institute, University of Minnesota Medical School, Minneapolis, Minnesota, USA

1Department of Medicine, University of Minnesota Medical School, Minneapolis, Minnesota, USA

1Department of Medicine, University of Minnesota Medical School, Minneapolis, Minnesota, USA

2Stem Cell Institute, University of Minnesota Medical School, Minneapolis, Minnesota, USA

3Department of Biomedical Engineering, University of Minnesota, Minneapolis, Minnesota, USA

1Department of Medicine, University of Minnesota Medical School, Minneapolis, Minnesota, USA

2Stem Cell Institute, University of Minnesota Medical School, Minneapolis, Minnesota, USA

3Department of Biomedical Engineering, University of Minnesota, Minneapolis, Minnesota, USA

Received 2012 Jun 11; Revised 2012 Jul 31; Accepted 2012 Aug 27.

Induced pluripotent stem (iPS) cells, are a type of pluripotent stem cell derived from adult somatic cells. They have been reprogrammed through inducing genes and factors to be pluripotent. iPS cells are similar to embryonic stem (ES) cells in many aspects. This review summarizes the recent progresses in iPS cell reprogramming and iPS cell based therapy, and describe patient specific iPS cells as a disease model at length in the light of the literature. This review also analyzes and discusses the problems and considerations of iPS cell therapy in the clinical perspective for the treatment of disease.

Keywords: Cellular therapy, disease model, embryonic stem cells, induced pluripotent stem cells, reprogramm.

Induced pluripotent stem (iPS) cells, are a type of pluripotent stem cell derived from adult somatic cells that have been genetically reprogrammed to an embryonic stem (ES) cell-like state through the forced expression of genes and factors important for maintaining the defining properties of ES cells.

Mouse iPS cells from mouse fibroblasts were first reported in 2006 by the Yamanaka lab at Kyoto University [1]. Human iPS cells were first independently produced by Yamanakas and Thomsons groups from human fibroblasts in late 2007 [2, 3]. iPS cells are similar to ES cells in many aspects, including the expression of ES cell markers, chromatin methylation patterns, embryoid body formation, teratoma formation, viable chimera formation, pluripotency and the ability to contribute to many different tissues in vitro.

The breakthrough discovery of iPS cells allow researchers to obtain pluripotent stem cells without the controversial use of embryos, providing a novel and powerful method to "de-differentiate" cells whose developmental fates had been traditionally assumed to be determined. Furthermore, tissues derived from iPS cells will be a nearly identical match to the cell donor, which is an important factor in research of disease modeling and drug screening. It is expected that iPS cells will help researchers learn how to reprogram cells to repair damaged tissues in the human body.

The purpose of this paper is to summarize the recent progresses in iPS cell development and iPS cell-based therapy, and describe patient specific iPS cells as a disease model, analyze the problems and considerations of iPS therapy in the clinical treatment of disease.

The methods of reprogramming somatic cells into iPS cells are summarized in Table . It was first demonstrated that genomic integration and high expression of four factors, Oct4/Sox2/Klf4/c-Myc or Oct4/Sox2/Nanog/LIN28 by virus, can reprogram fibroblast cells into iPS cells [1-3]. Later, it was shown that iPS cells can be generated from fibroblasts by viral integration of Oct4/Sox2/Klf4 without c-Myc [4]. Although these iPS cells showed reduced tumorigenicity in chimeras and progeny mice, the reprogramming process is much slower, and efficiency is substantially reduced. These studies suggest that the ectopic expression of these three transcription factors (Oct4/Klf4/Sox2) is required for reprogramming of somatic cells in iPS cells.

Various growth factors and chemical compounds have recently been found to improve the induction efficiency of iPS cells. Shi et al., [5] demonstrated that small molecules, able to compensate for Sox2, could successfully reprogram mouse embryonic fibroblasts (MEF) into iPS cells. They combined Oct4/Klf4 transduction with BIX-01294 and BayK8644s and derived MEF into iPS cells. Huangfu et al., [6, 7] reported that 5-azacytidine, DNA methyltransferase inhibitor, and valproic acid, a histone deacetylase inhibitor, improved reprogramming of MEF by more than 100 folds. Valproic acid enables efficient reprogramming of primary human fibroblasts with only Oct4 and Sox2.

Kim et al. showed that mouse neural stem cells, expressing high endogenous levels of Sox2, can be reprogrammed into iPS cells by transduction Oct4 together with either Klf4 or c-Myc [19]. This suggests that endogenous expression of transcription factors, that maintaining stemness, have a role in the reprogramming process of pluripotency. More recently, Tsai et al., [20] demonstrated that mouse iPS cells could be generated from the skin hair follicle papilla (DP) cell with Oct4 alone since the skin hair follicle papilla cells expressed endogenously three of the four reprogramming factors: Sox2, c-Myc, and Klf4. They showed that reprogramming could be achieved after 3 weeks with efficiency similar to other cell types reprogrammed with four factors, comparable to ES cells.

Retroviruses are being extensively used to reprogram somatic cells into iPS cells. They are effective for integrating exogenous genes into the genome of somatic cells to produce both mouse and human iPS cells. However, retroviral vectors may have significant risks that could limit their use in patients. Permanent genetic alterations, due to multiple retroviral insertions, may cause retrovirus-mediated gene therapy as seen in treatment of severe combined immunodeficiency [25]. Second, although retroviral vectors are silenced during reprogramming [26], this silencing may not be permanent, and reactivation of transgenes may occur upon the differentiation of iPS cells. Third, expression of exogenous reprogramming factors could occur. This may trigger the expression of oncogenes that stimulate cancer growth and alter the properties of the cells. Fourth, the c-Myc over-expression may cause tumor development after transplantation of iPS derived cells. Okita et al. [10] reported that the chimeras and progeny derived from iPS cells frequently showed tumor formation. They found that the retroviral expression of c-Myc was reactivated in these tumors. Therefore, it would be desirable to produce iPS cells with minimal, or free of, genomic integration. Several new strategies have been recently developed to address this issue (Table ).

Stadtfeld et al. [16] used an adenoviral vector to transduce mouse fibroblasts and hepatocytes, and generated mouse iPS cells at an efficiency of about 0.0005%. Fusaki et al. [22] used Sendai virus to efficiently generate iPS cells from human skin fibroblasts without genome integration. Okita et al. [27] repeatedly transfected MEF with two plasmids, one carrying the complementary DNAs (cDNAs) of Oct3/4, Sox2, and Klf4 and the other carrying the c-Myc cDNA. This generated iPS cells without evidence of plasmid integration. Using a polycistronic plasmid co-expressing Oct4, Sox2, Klf4, and c-Myc, Gonzalez et al., [28] reprogrammed MEF into iPS cells without genomic integration. Yu et al. [29] demonstrated that oriP/EBNA1 (EpsteinBarr nuclear antigen-1)-based episomal vectors could be used to generate human iPS cells free of exogenous gene integration. The reprogramming efficiency was about 36 colonies/1 million somatic cells. Narsinh et al., [21] derived human iPS cells via transfection of human adipocyte stromal cells with a nonviral minicircle DNA by repeated transfection. This produced hiPS cells colonies from an adipose tissue sample in about 4 weeks.

When iPS cells generated from either plasmid transfection or episomes were carefully analyzed to identify random vector integration, it was possible to have vector fragments integrated somewhere. Thus, reprogramming strategies entirely free of DNA-based vectors are being sought. In April 2009, it was shown that iPS cells could be generated using recombinant cell-penetrating reprogramming proteins [30]. Zhou et al. [30] purified Oct4, Sox2, Klf4 and c-Myc proteins, and incorporated poly-arginine peptide tags. It allows the penetration of the recombinant reprogramming proteins through the plasma membrane of MEF. Three iPS cell clones were successfully generated from 5x 104 MEFs after four rounds of protein supplementation and subsequent culture of 2328 days in the presence of valproic acid.

A similar approach has also been demonstrated to be able to generate human iPS cells from neonatal fibroblasts [31]. Kim et al. over-expressed reprogramming factor proteins in HEK293 cells. Whole cell proteins of the transduced HEK293 were extracted and used to culture fibroblast six times within the first week. After eight weeks, five cell lines had been established at a yield of 0.001%, which is one-tenth of viral reprogramming efficiency. Strikingly, Warren et al., [24] demonstrated that human iPS cells can be derived using synthetic mRNA expressing Oct3/4, Klf4, Sox2 and c-Myc. This method efficiently reprogrammed fibroblast into iPS cells without genome integration.

Strenuous efforts are being made to improve the reprogramming efficiency and to establish iPS cells with either substantially fewer or no genetic alterations. Besides reprogramming vectors and factors, the reprogramming efficiency is also affected by the origin of iPS cells.

A number of somatic cells have been successfully reprogrammed into iPS cells (Table ). Besides mouse and human somatic cells, iPS cells from other species have been successfully generated (Table ).

The origin of iPS cells has an impact on choice of reprogramming factors, reprogramming and differentiation efficiencies. The endogenous expression of transcription factors may facilitate the reprogramming procedure [19]. Mouse neural stem cells express higher endogenous levels of Sox2 and c-Myc than ES cells. Thus, two transcription factors, exogenous Oct4 together with either Klf4 or c-Myc, are sufficient to generate iPS cells from neural stem cells [19]. Ahmed et al. [14] demonstrated that mouse skeletal myoblasts endogenously expressed Sox2, Klf4, and c-Myc and can be easily reprogrammed to iPS cells.

It is possible that iPS cells may demonstrate memory of parental source and therefore have low differentiation efficiency into other tissue cells. Kim et al. [32] showed that iPS cells reprogrammed from peripheral blood cells could efficiently differentiate into the hematopoietic lineage cells. It was found, however, that these cells showed very low differentiation efficiency into neural cells. Similarly, Bar-Nur et al. found that human cell-derived iPS cells have the epigenetic memory and may differentiate more readily into insulin producing cells [33]. iPS cells from different origins show similar gene expression patterns in the undifferentiated state. Therefore, the memory could be epigenetic and are not directly related to the pluripotent status.

The cell source of iPS cells can also affect the safety of the established iPS cells. Miura et al. [54] compared the safety of neural differentiation of mouse iPS cells derived from various tissues including MEFs, tail-tip fibroblasts, hepatocyte and stomach. Tumorigenicity was examined. iPS cells that reprogrammed from tail-tip fibroblasts showed many undifferentiated pluripotent cells after three weeks of in vitro differentiation into the neural sphere. These cells developed teratoma after transplantation into an immune-deficient mouse brain. The possible mechanism of this phenomenon may be attributable to epigenetic memory and/or genomic stability. Pre-evaluated, non-tumorigenic and safe mouse iPS cells have been reported by Tsuji et al. [55]. Safe iPS cells were transplanted into non-obese diabetic/severe combined immunodeficiency mouse brain, and found to produce electrophysiologically functional neurons, astrocytes, and oligodendrocytes in vitro.

The cell source of iPS cells is important for patients as well. It is important to carefully evaluate clinically available sources. Human iPS cells have been successfully generated from adipocyte derived stem cells [35], amniocytes [36], peripheral blood [38], cord blood [39], dental pulp cells [40], oral mucosa [41], and skin fibroblasts (Table ). The properties and safety of these iPS cells should be carefully examined before they can be used for treatment.

Shimada et al. [17] demonstrated that combination of chemical inhibitors including A83-01, CHIR99021, PD0325901, sodium butyrate, and Y-27632 under conditions of physiological hypoxia human iPS cells can be rapidly generated from adipocyte stem cells via retroviral transduction of Oct4, Sox2, Klf4, and L-Myc. Miyoshi et al., [42] generated human iPS cells from cells isolated from oral mucosa via the retroviral gene transfer of Oct4, Sox2, c-Myc, and Klf4. Reprogrammed cells showed ES-like morphology and expressed undifferentiated markers. Yan et al., [40] demonstrated that dental tissue-derived mesenchymal-like stem cells can easily be reprogrammed into iPS cells at relatively higher rates as compared to human fibroblasts. Human peripheral blood cells have also been successfully reprogrammed into iPS cells [38]. Anchan et al. [36] described a system that can efficiently derive iPS cells from human amniocytes, while maintaining the pluripotency of these iPS cells on mitotically inactivated feeder layers prepared from the same amniocytes. Both cellular components of this system are autologous to a single donor. Takenaka et al. [39] derived human iPS cells from cord blood. They demonstrated that repression of p53 expression increased the reprogramming efficiency by 100-fold.

All of the human iPS cells described here are indistinguishable from human ES cells with respect to morphology, expression of cell surface antigens and pluripotency-associated transcription factors, DNA methylation status at pluripotent cell-specific genes and the capacity to differentiate in vitro and in teratomas. The ability to reprogram cells from human somatic cells or blood will allow investigating the mechanisms of the specific human diseases.

The iPS cell technology provides an opportunity to generate cells with characteristics of ES cells, including pluripotency and potentially unlimited self-renewal. Studies have reported a directed differentiation of iPS cells into a variety of functional cell types in vitro, and cell therapy effects of implanted iPS cells have been demonstrated in several animal models of disease.

A few studies have demonstrated the regenerative potential of iPS cells for three cardiac cells: cardiomyocytes, endothelial cells, and smooth muscle cells in vitro and in vivo. Mauritz [56] and Zhang [57] independently demonstrated the ability of mouse and human iPS cells to differentiate into functional cardiomyocytes in vitro through embryonic body formation. Rufaihah [58], et al. derived endothelial cells from human iPS cells, and showed that transplantation of these endothelial cells resulted in increased capillary density in a mouse model of peripheral arterial disease. Nelson et al. [59] demonstrated for the first time the efficacy of iPS cells to treat acute myocardial infarction. They showed that iPS cells derived from MEF could restore post-ischemic contractile performance, ventricular wall thickness, and electrical stability while achieving in situ regeneration of cardiac, smooth muscle, and endothelial tissue. Ahmed et al. [14] demonstrated that beating cardiomyocyte-like cells can be differentiated from iPS cells in vitro. The beating cells expressed early and late cardiac-specific markers. In vivo studies showed extensive survival of iPS and iPS-derived cardiomyocytes in mouse hearts after transplantation in a mouse experimental model of acute myocardial infarction. The iPs derived cardiomyocyte transplantation attenuated infarct size and improved cardiac function without tumorgenesis, while tumors were observed in the direct iPS cell transplantation animals.

Strategies to enhance the purity of iPS derived cardiomyocytes and to exclude the presence of undifferentiated iPS are required. Implantation of pre-differentiation or guided differentiation of iPS would be a safer and more effective approach for transplantation. Selection of cardiomyocytes from iPS cells, based on signal-regulatory protein alpha (SIRPA) or combined with vascular cell adhesion protein-1 (VCAM-1), has been reported. Dubois et al. [60] first demonstrated that SIRPA was a marker specifically expressed on cardiomyocytes derived from human ES cells and human iPS cells. Cell sorting with an antibody against SIRPA could enrich cardiac precursors and cardiomyocytes up to 98% troponin T+ cells from human ESC or iPS cell differentiation cultures. Elliott et al. [61] adopted a cardiac-specific reporter gene system (NKX2-5eGFP/w) and identified that VCAM-1 and SIRPA were cell-surface markers of cardiac lineage during differentiation of human ES cells.

Regeneration of functional cells from human stem cells represents the most promising approach for treatment of type 1 diabetes mellitus (T1DM). This may also benefit the patients with type 2 diabetes mellitus (T2DM) who need exogenous insulin. At present, technology for reprogramming human somatic cell into iPS cells brings a remarkable breakthrough in the generation of insulin-producing cells.

Human ES cells can be directed to become fully developed cells and it is expected that iPS cells could also be similarly differentiated. Stem cell based approaches could also be used for modulation of the immune system in T1DM, or to address the problems of obesity and insulin resistance in T2DM.

Tateishi et al., [62] demonstrated that insulin-producing islet-like clusters (ILCs) can be generated from the human iPS cells under feeder-free conditions. The iPS cell derived ILCs not only contain C-peptide positive and glucagon-positive cells but also release C-peptide upon glucose stimulation. Similarly, Zhang et al., [63] reported a highly efficient approach to induce human ES and iPS cells to differentiate into mature insulin-producing cells in a chemical-defined culture system. These cells produce insulin/C-peptide in response to glucose stimuli in a manner comparable to that of adult human islets. Most of these cells co-expressed mature cell-specific markers such as NKX6-1 and PDX1, indicating a similar gene expression pattern to adult islet beta cells in vivo.

Alipo et al. [64] used mouse skin derived iPS cells for differentiation into -like cells that were similar to the endogenous insulin-secreting cells in mice. These -like cells were able to secrete insulin in response to glucose and to correct a hyperglycemic phenotype in mouse models of both T1DM and T2DM after iPS cell transplant. A long-term correction of hyperglycemia could be achieved as determined by hemoglobin A1c levels. These results are encouraging and suggest that induced pluripotency is a viable alternative to directing iPS cell differentiation into insulin secreting cells, which has great potential clinical applications in the treatment of T1DM and T2 DM.

Although significant progress has been made in differentiating pluripotent stem cells to -cells, several hurdles remain to be overcome. It is noted in several studies that the general efficiency of in vitro iPS cell differentiation into functional insulin-producing -like cells is low. Thus, it is highly essential to develop a safe, efficient, and easily scalable differentiation protocol before its clinical application. In addition, it is also important that insulin-producing b-like cells generated from the differentiation of iPS cells have an identical phenotype resembling that of adult human pancreatic cells in vivo.

Currently, the methodology of neural differentiation has been well established in human ES cells and shown that these methods can also be applied to iPS cells. Chambers et al. [65] demonstrated that the synergistic action of Noggin and SB431542 is sufficient to induce rapid and complete neural conversion of human ES and iPS cells under adherent culture conditions. Swistowsk et al. [66] used a completely defined (xenofree) system, that has efficiently differentiated human ES cells into dopaminergic neurons, to differentiate iPS cells. They showed that the process of differentiation into committed neural stem cells (NSCs) and subsequently into dopaminergic neurons was similar to human ES cells. Importantly, iPS cell derived dopaminergic neurons were functional as they survived and improved behavioral deficits in 6-hydroxydopamine-leasioned rats after transplantation. Lee et al. [67] provided detailed protocols for the step-wise differentiation of human iPS and human ES into neuroectodermal and neural crest cells using either the MS5 co-culture system or a defined culture system (Noggin with a small-molecule SB431542), NSB system. The average time required for generating purified human NSC precursors will be 25 weeks. The success of deriving neurons from human iPS cells provides a study model of normal development and impact of genetic disease during neural crest development.

Wernig et al., [68] showed that iPS cells can give rise to neuronal and glial cell types in culture. Upon transplantation into the fetal mouse brain, the cells differentiate into glia and neurons, including glutamatergic, GABAergic, and catecholaminergic subtypes. Furthermore, iPS cells were induced to differentiate into dopamine neurons of midbrain character and were able to improve behavior in a rat model of Parkinson's disease (PD) upon transplantation into the adult brain. This study highlights the therapeutic potential of directly reprogrammed fibroblasts for neural cell replacement in the animal model of Parkinsons disease.

Tsuji et al., [55] used pre-evaluated iPS cells derived for treatment of spinal cord injury. These cells differentiated into all three neural lineages, participated in remyelination and induced the axonal regrowth of host 5HT+ serotonergic fibers, promoting locomotor function recovery without forming teratomas or other tumors. This study suggests that iPS derived neural stem/progenitor cells may be a promising cell source for treatment of spinal cord injury.

Hargus et al., [69] demonstrated proof of principle of survival and functional effects of neurons derived from iPS cells reprogrammed from patients with PD. iPS cells from patients with Parkinsons disease were differentiated into dopaminergic neurons that could be transplanted without signs of neuro-degeneration into the adult rodent striatum. These cells survived and showed arborization, and mediated functional effects in an animal model of Parkinsons disease. This study suggests that disease specific iPS cells can be generated from patients with PD, which be used to study the PD development and in vitro drug screen for treatment of PD.

Reprogramming technology is being applied to derive patient specific iPS cell lines, which carry the identical genetic information as their patient donor cells. This is particularly interesting to understand the underlying disease mechanism and provide a cellular and molecular platform for developing novel treatment strategy.

Human iPS cells derived from somatic cells, containing the genotype responsible for the human disease, hold promise to develop novel patient-specific cell therapies and research models for inherited and acquired diseases. The differentiated cells from reprogrammed patient specific human iPS cells retain disease-related phenotypes to be an in vitro model of pathogenesis (Table ). This provides an innovative way to explore the molecular mechanisms of diseases.

Disease Modeling Using Human iPS Cells

Recent studies have reported the derivation and differentiation of disease-specific human iPS cells, including autosomal recessive disease (spinal muscular atrophy) [70], cardiac disease [71-75], blood disorders [13, 76], diabetes [77], neurodegenerative diseases (amyotrophic lateral sclerosis [78], Huntingtons disease [79]), and autonomic nervous system disorder (Familial Dysautonomia) [80]. Patient-specific cells make patient-specific disease modeling possible wherein the initiation and progression of this poorly understood disease can be studied.

Human iPS cells have been reprogrammed from spinal muscular atrophy, an autosomal recessive disease. Ebert et al., [70] generated iPS cells from skin fibroblast taken from a patient with spinal muscular atrophy. These cells expanded robustly in culture, maintained the disease genotype and generated motor neurons that showed selective deficits compared to those derived from the patients' unaffected relative. This is the first study to show that human iPS cells can be used to model the specific pathology seen in a genetically inherited disease. Thus, it represents a promising resource to study disease mechanisms, screen new drug compounds and develop new therapies.

Similarly, three other groups reported their findings on the use of iPS cells derived cardiomyocytes (iPSCMs) as disease models for LQTS type-2 (LQTS2). Itzhaki et al., [72] obtained dermal fibroblasts from a patient with LQTS2 harboring the KCNH2 gene mutation and showed that action potential duration was prolonged and repolarization velocity reduced in LQTS2 iPS-CMs compared with normal cardiomyocytes. They showed that Ikr was significantly reduced in iPS-CMs derived from LQTS2. They also tested the potential therapeutic effects of nifedipine and the KATP channel opener pinacidil (which augments the outward potassium current) and demonstrated that they shortened the action potential duration and abolished early after depolarization. Similarly, Lahti et al., [73] demonstrated a more pronounced inverse correlation between the beating rate and repolarization time of LQTS2 disease derived iPS-CMs compared with normal control cells. Prolonged action potential is present in LQT2-specific cardiomyocytes derived from a mutation. Matsa et al., [74] also successfully generated iPS-CMs from a patient with LQTS2 with a known KCNH2 mutation. iPS-CMs with LQTS2 displayed prolonged action potential durations on patch clamp analysis and prolonged corrected field potential durations on microelectrode array mapping. Furthermore, they demonstrated that the KATP channel opener nicorandil and PD-118057, a type 2 IKr channel enhancer attenuate channel closing.

LQTS3 has been recapitulated in mouse iPS cells [75]. Malan et al. [75] generated disease-specific iPS cells from a mouse model of a human LQTS3. Patch-clamp measurements of LQTS 3-specific cardiomyocytes showed the biophysical effects of the mutation on the Na+ current, withfaster recovery from inactivation and larger late currents than observed in normal control cells. Moreover, LQTS3-specific cardiomyocytes had prolonged action potential durations and early after depolarizations at low pacing rates, both of which are classic features of the LQTS3 mutation.

Human iPS cells have been used to recapitulate diseases of blood disorder. Ye et al. [13] demonstrated that human iPS cells derived from periphery blood CD34+ cells of patients with myeloproliferative disorders, have the JAK2-V617F mutation in blood cells. Though the derived iPS cells contained the mutation, they appeared normal in phenotypes, karyotype, and pluripotency. After hematopoietic differentiation, the iPS cell-derived hematopoietic progenitor (CD34+/CD45+) cells showed the increased erythropoiesis and expression of specific genes, recapitulating features of the primary CD34+ cells of the corresponding patient from whom the iPS cells were derived. This study highlights that iPS cells reprogrammed from somatic cells from patients with blood disease provide a prospective hematopoiesis model for investigating myeloproliferative disorders.

Raya et al., [76] reported that somatic cells from Fanconi anaemia patients can be reprogrammed to pluripotency after correction of the genetic defect. They demonstrated that corrected Fanconi-anaemia specific iPS cells can give rise to haematopoietic progenitors of the myeloid and erythroid lineages that are phenotypically normal. This study offers proof-of-concept that iPS cell technology can be used for the generation of disease-corrected, patient-specific cells with potential value for cell therapy applications.

Maehr et al., [77] demonstrated that human iPS cells can be generated from patients with T1DM by reprogramming their adult fibroblasts. These cells are pluripotent and differentiate into three lineage cells, including insulin-producing cells. These cells provide a platform to assess the interaction between cells and immunocytes in vitro, which mimic the pathological phenotype of T1DM. This will lead to better understanding of the mechanism of T1DM and developing effective cell replacement therapeutic strategy.

Lee et al., [80] reported the derivation of human iPS cells from patient with Familial Dysautonomia, an inherited disorder that affects the development and function of nerves throughout the body. They demonstrated that these iPS cells can differentiate into all three germ layers cells. However gene expression analysis demonstrated tissue-specific mis-splicing of IKBKAP in vitro, while neural crest precursors showed low levels of normal IKBKAP transcript. Transcriptome analysis and cell-based assays revealed marked defects in neurogenic differentiation and migration behavior. All these recaptured familial Dysautonomia pathogenesis, suggesting disease specificity of the with familial Dysautonomia human iPS cells. Furthermore, they validated candidate drugs in reversing and ameliorating neuronal differentiation and migration. This study illustrates the promise of disease specific iPS cells for gaining new insights into human disease pathogenesis and treatment.

Human iPS cells derived reprogrammed from patients with inherited neurodegenerative diseases, amyotrophic lateral sclerosis [78] and Huntingtons disease 79, have also been reported. Dimos et al., [78] showed that they generated iPS cells from a patient with a familial form of amyotrophic lateral sclerosis. These patient-specific iPS cells possess the properties of ES cells and were reprogrammed successfully to differentiate into motor neurons. Zhang et al., [79] derived iPS cells from fibroblasts of patient with Huntingtons disease. They demonstrated that striatal neurons and neuronal precursors derived from these iPS cells contained the same CAG repeat expansion as the mutation in the patient from whom the iPS cell line was established. This suggests that neuronal progenitor cells derived from Huntingtons disease cell model have endogenous CAG repeat expansion that is suitable for mechanistic studies and drug screenings.

Disease specific somatic cells derived from patient-specific human iPS cells will generate a wealth of information and data that can be used for genetically analyzing the disease. The genetic information from disease specific-iPS cells will allow early and more accurate prediction and diagnosis of disease and disease progression. Further, disease specific iPS cells can be used for drug screening, which in turn correct the genetic defects of disease specific iPS cells.

iPS cells appear to have the greatest promise without ethical and immunologic concerns incurred by the use of human ES cells. They are pluripotent and have high replicative capability. Furthermore, human iPS cells have the potential to generate all tissues of the human body and provide researchers with patient and disease specific cells, which can recapitulate the disease in vitro. However, much remains to be done to use these cells for clinical therapy. A better understanding of epigenetic alterations and transcriptional activity associated with the induction of pluripotency and following differentiation is required for efficient generation of therapeutic cells. Long-term safety data must be obtained to use human iPS cell based cell therapy for treatment of disease.

These works were supported by NIH grants HL95077, HL67828, and UO1-100407.

The authors confirm that this article content has no conflicts of interest.

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