Oncology drugs are therapeutics used to treat cancer, a group of diseases caused by uncontrolled growth and division of abnormal cells. Oncology drugs include a range of different types of medications, such as chemotherapy agents, targeted therapies, immunotherapies, and hormone therapies. There are also different types of drugs available to help treat the side effects from oncology drugs.

If you have cancer, its likely youll have a few options when it comes to treatment. Cancer treatment is constantly evolving and progressing. You now have more drug options to choose from than ever before.

A doctor may recommend that you treat your cancer with one or more of the following types of oncology drugs:

Chemotherapy drugs are chemical agents that work by destroying fast-growing cells in the body. Cancer cells grow and divide more rapidly than other cells. The goal of chemotherapy is to lower the total number of cancer cells in your body and reduce the chances that the cancer will spread to other parts of the body (metastasize).

There are at least 61 chemotherapy drugs approved in the United States. Your doctor may decide to treat your cancer with a a single chemotherapy drug or a combination of chemotherapy drugs.

Hormone therapy is used to treat cancers that rely on hormones to grow. This may include certain types of breast cancer and prostate cancer. Breast cancers may be fed by estrogen or progesterone, while prostate cancers often depend on the hormone androgen.

Some examples of hormone therapies include:

Targeted therapies are part of a new approach known as personalized medicine or precision medicine. Targeted therapies are able to seek out and kill cancerous cells without harming the normal cells in your body. These drugs work by blocking the molecular pathways that are critical to tumor growth.

To see if youre eligible for a particular targeted therapy, a doctor will first perform genetic or biomarker testing. The results of this testing will allow your doctor to make an informed decision about which drug is more likely to work for your type of cancer, based on the genetic mutations or other molecular characteristics of your tumor.

Examples of targeted oncology drugs include:

Immunotherapy is a type of targeted therapy that uses the bodys own immune system to attack cancer cells. Cancer cells sometimes have strategic ways of hiding from your immune system, but immunotherapies work by blocking these mechanisms.

Immunotherapies are approved to treat a variety of cancers. Examples include:

To counter the side effects of oncology drugs, your oncologist may prescribe additional medications. Examples include:

Oncology drugs have many benefits. Depending on your individual cancer, these drugs may:

On the other hand, oncology drugs often have side effects and risks. Chemotherapy, for example, can attack some of the normal cells in your body especially blood cells, skin, hair, and the cells lining the intestine and mouth. This can cause serious side effects that can negatively impact your quality of life.

Common side effects of chemotherapy include:

Targeted therapies and immunotherapies often have fewer side effects compared to chemotherapy since they only attack cancer cells while sparing healthy cells from harm, but they can still cause side effects. These may include:

Hormone therapies can block your bodys ability to make hormones, and can interfere with how hormones act in your body. Some common side effects of hormone therapies include:

Apart from oncology drugs, there are other treatments available for cancer, including:

Other therapies such as acupuncture, meditation, and herbal supplements may help with side effects of cancer treatment, but are ineffective at treating the cancer itself.

Yes, you can have a say in your cancer treatment, including making the decision to delay treatment or not have treatment at all. You can also seek a second opinion from another qualified doctor. Dont hesitate to ask your doctor for resources so you can do your own research on available treatments before you make a decision.

Ask your doctor about clinical trials taking place in your area. The National Institutes of Health (NIH) maintains a large database of clinical trials at clinicaltrials.gov. You can also search the National Cancer Institute (NCI)s online tool or contact them for help at 800-4-CANCER.

There are over 100 types of cancer, according to the National Cancer Institute (NCI). Your oncologist will formulate a recommended treatment plan based on the type of cancer you have, the stage or grade of the cancer, the characteristics of your tumor, your age, overall health, and several other considerations.

To determine the best treatment for you, your oncologist may perform molecular testing on your tumor among other imaging and blood tests. He or she will also likely consult with medical guidelines, such as those set forth by the National Comprehensive Cancer Network (NCCN).

To treat cancer, your doctor may recommend one type of oncology drug or a combination of drugs alongside surgery, radiation, or other types of treatment.

Before deciding to move forward with a cancer drug, learn as much as you can about the recommended treatment. Ask your doctor about benefits and risks of your recommended treatment plan and work together to make an informed decision.

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Types of Oncology Drugs - Healthline

Bone Marrow Stem Cells Comments Off on Types of Oncology Drugs – Healthline | October 28th, 2021

The COVID-19 pandemic has created a sense of urgency to generate new drugs and vaccines. In many cases, this urgency became a regulatory opportunity to bypass established regulatory pathways for new drugs.

While this has led to the fast emergence of many useful drugs and vaccines for COVID-19, it has also led to a general reduction in the quality of medical research from which to derive conclusions.

For example, according to Janet Woodcock, former director of the Food and Drug Administrations (FDA) Center for Drug Evaluation and Research, an FDA analysis found that 6% of clinical trials are yielding results the agency deems actionable.

The lack of regulation coupled with a sense of urgency has also led to overhype and rushed development of certain treatments, including cell-based therapies often sold as stem cell treatments.

While some of these products have undergone well-designed, adequately controlled trials, most are in the early stages. Some clinics are nevertheless offering these unproven and unlicensed treatments to people, promising to boost their immune system or overall health to protect against COVID-19.

Promoting and selling unproven and unlicensed treatments can harm public health and could lead many to undergo untested and potentially harmful treatments.

Recently, a group of researchers from the University of California, Irvine, the Georgia Institute of Technology, the University at Buffalo, NY, and the University of Melbourne in Australia, published a report outlining misinformation around cell-based treatments for COVID-19, calling for their stronger regulation.

Efforts to rapidly develop therapeutic interventions should never occur at the expense of the ethical and scientific standards that are at the heart of responsible clinical research and innovation, said Dr. Laertis Ikonomou, assistant professor of Oral Biology at the University at Buffalo, and co-author of the study.

Scientists, regulators, and policymakers must guard against the proliferation of poorly designed, underpowered, and duplicative studies that are launched with undue haste because of the pandemic, but are unlikely to provide convincing, clinically meaningful safety and efficacy data, said co-author Dr. Leigh Turner, professor of Health, Society and Behavior at the University of California, Irvine.

The researchers published their report in Stem Cell Reports.

Researchers conducted a study in August 2020 of 70 clinical trials involving cell-based treatments for COVID-19. They found that most were small, with an average of 51.8 participants, and only 22.8% were randomized, double-blinded, and controlled experiments.

The authors concluded that the cell-based interventions for COVID-19 were likely to have a relatively small collective clinical impact.

Cell-based treatments for COVID-19 are still at an experimental stage, Dr. Ikonomou told Medical News Today. There are tens of clinical trials, of varied complexity and rigor, that evaluate various cell types, such as mesenchymal stromal cells, for COVID-19 treatment.

Expanded or compassionate use of cell-based interventions has also been reported, but these individual cases are unlikely to tell us whether and how cell therapies could help with COVID-19 and do not substitute for the systematic clinical evaluation of cell-based products, he added.

A few completed phase 1/2 trials have shown a favorable safety profile, but larger size trials are required. Eventually, properly-powered, controlled, randomized, double-blinded clinical trials will help determine whether cell-based treatments are a viable therapeutic option for COVID-19 and its complications, he explained.

The urgency of the pandemic has made it easy to exaggerate early-stage research. The scientists highlight this is especially the case in press releases, where media professionals can over-hype findings and understate or omit limitations to gain more media coverage.

The researchers also say that even when online media include limitations and key aspects of studies, other communication channels can strip these away easily. What is left then gets amplified, as the public is desperate to see positive news.

To address this, the researchers say science communicators should ensure they have an accurate understanding of the information they report and highlight the required steps for the science to advance without exaggerating its speed.

The researchers also say that simply feeding the public more information in what is known as the information deficit model alone is insufficient. They also suggest science communicators should strive for an engaged or dialogue-based communication approach.

Over-hyping of promising treatments and in particular cell-based treatments has been a longstanding problem, and it did not first emerge with the COVID-19 pandemic, said Dr. Ikonomou. It has become a salient issue during these times due to the global nature of this health emergency and the resulting devastation and health toll.

Therefore, it is even more important to communicate promising developments in COVID-19-related science and clinical management [responsibly]. Key features of good communication are an accurate understanding of new findings, including study limitations and avoidance of sensationalist language, he explained.

Realistic timeframes for clinical translation are equally important as is the realization that promising interventions at preliminary stages may not always translate to proven treatments following rigorous testing, he added.

The researchers say that commercial investments by biotechnology companies to develop cell-based therapies for COVID-19 have led to well-designed and rigorous clinical trials.

However, some other businesses have overlooked the demanding process of pre-marketing authorization of their products. Instead, they made unsubstantiated and inaccurate claims about their stem cell products for COVID-19 based on hyperbolic reporting of cell-based therapies in early testing.

Some clinics advertise unproven and unlicensed mesenchymal stem cell treatments or exosome therapies as immune boosters that prevent COVID-19 and repair and regenerate lungs.

Often, these businesses make their treatments available via infusion or injection. However, one anti-aging clinic in California shipped its kits to clients, where they were to self-administer with a nebulizer and mask.

Such companies often market stem cell treatments via online and social media. In an initial review of many of these brands, the researchers could not find published findings from preclinical studies and clinical trials to support their commercial activities.

Instead, they found that these companies drew from uncritical news media reports, preliminary clinical studies, or case reports in which those diagnosed with COVID-19 received stem cell interventions.

Promoting such therapies that have not undergone proper tests for safety and efficacy have the potential for significant physical and financial harm.

Health experts have documented adverse events due to unlicensed stem cell products, including vision loss and autoimmune, infectious, neurological, and cardiovascular complications.

Early in the pandemic, scientific and professional societies, including the Alliance for Regenerative Medicine and the International Society for Stem Cell Research, have warned the public against businesses engaged in the marketing of cell-based treatments that have not undergone adequate testing.

The researchers highlight that it is unclear whether these warnings reached individuals and their loved ones or significantly affected public understanding of the risks of receiving unlicensed and unproven stem cell treatments for COVID-19.

They also indicate that it is unclear whether these societies and organizations have an important role in convincing regulatory bodies to increase enforcement in this space. Nevertheless, at the time of writing, the FDA and Federal Trade Commission have issued 22 letters to businesses selling unproven and unlicensed cell-based therapies.

And while many of these companies have ceased market activity, the presence of other companies continuing to pedal the same claims makes it clear that regulatory bodies must increase their enforcement.

Additionally, the researchers question whether warning letters are sufficient to disincentivize clinicians and others to sell unlicensed products. They write:

If companies and affiliated clinicians are not fined, forced to return to patients whatever profits they have made, confronted with criminal charges, subject to revocation of medical licensure, or otherwise subject to serious legal and financial consequences, it is possible that more businesses will be drawn to this space because of the profits that can be generated from selling unlicensed and unproven cell-based products in the midst of a pandemic.

The researchers conclude that regulators should increase enforcement against unproven and unlicensed therapies for COVID-19.

They also say that science communicators should report on scientific claims more realistically and include the public in more discourse.

In the U.S. and elsewhere, there are regulations and enforcement mechanisms that deal with harms caused by unproven and unlicensed cell-based interventions and false advertising claims, said Dr. Ikonomou. It may be preferable to implement existing regulations more vigorously than introduce new ones.

Stakeholders, such as scientific, professional, and medical associations, can contribute towards this goal with reporting and monitoring of cell therapy misinformation. There is a shared responsibility to combat cell-therapy related misinformation and disinformation that undercuts legitimate research and clinical efforts and portrays unproven interventions as silver bullets for COVID-19, he concluded.

For live updates on the latest developments regarding the novel coronavirus and COVID-19, click here.

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COVID-19: Researchers warn against overhyping early-stage therapies - Medical News Today

Skin Stem Cells Comments Off on COVID-19: Researchers warn against overhyping early-stage therapies – Medical News Today | October 28th, 2021

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

Original post:
Managing superficial pyoderma with light therapy - DVM 360

Skin Stem Cells Comments Off on Managing superficial pyoderma with light therapy – DVM 360 | October 28th, 2021

At 42, Kate Hudson makes aging look effortlessand now we finally know why. In an Instagram video shared by True Botanicals, the actress revealed two products she can't live without in the morning: The Juice Beauty Stem Cellular Instant Eye Lift Algae Mask and True Botanicals Resurfacing Face Mask.

Organic Resurfacing Moisture Mask

$65.00

"Everybody loves a beauty tip. This is my morning routine: Juice Beauty Eye Patches and this Resurfacing Mask," Hudson says in the video. First, she puts on the eye patches and lets them set. Then, she applies the resurfacing face mask, making sure to cover her face and neck.

"Sometimes a little mask in the morning is my favorite way to wake up my skin. Cause my skin can get tiiiirrrreeeed ," she wrote in an Instagram post from April.

With stem cellular activator fluid and freeze-dried biomatrix algae, the Juice Beauty Eye Patches smooth out fine lines around the eyes in just 10 minutes. The best part? They only cost $10, and Juice Beauty customers say they really work. "There were instant results," one shopper wrote in a review. "The dark circles and puffiness under my eyes were almost gone."

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As for the True Botanicals Resurfacing Mask, this facial-in-a-jar has lactic acid, a chemical fermentation of lactoseto increase cell turnover and eliminate dead skin cells on the surface of the skin. In addition to exfoliating your pores, the face mask uses avocado butter to hydrate the skin. Basically, it's everything your skin needs to stay hydrated through the cold, dry winter months ahead.

Amazon shoppers love it, too. "This is the only resurfacing mask that doesn't irritate my skin and I use it once a week. Absolutely in love with this!" one customer wrote. Another person said they "could not be happier" with the results: "It leaves skin glowing and silky smooth."

Hudson previously told InStyle, she was inspired by her mom Goldie Hawn to start taking care of her skin. "For her, it's all about eating right, detoxifying, energizing your body, drinking water. But we do love our makeup and creams."

This content is imported from Instagram. You may be able to find the same content in another format, or you may be able to find more information, at their web site.

In addition to the Juice Beauty Eye Patches and True Botanical Resurfacing Face Mask, Hudson shared in an Instagram post that she also loves Symbiomes The Renewal Daily Cleanser, Tata Harpers Regenerating Cleanser, and Juice Beautys Resurfacing Micro-Exfoliant. She also never leaves the house without sunscreen.

But ultimately, for the actress, beauty starts on the inside. "I think number one is managing your stress, because when were stressed out, it shows all over. And if you are stressed, there are all sorts of things you can do," she told The Skincare Edit. "I think for me that's sort of where the beauty regimen starts, with healthmental and physical healthand then the fun stuff."

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Kate Hudson Shares Her Morning Beauty Routine on Instagram - Prevention.com

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Using BK virus (BKV)-specific T cells from healthy donors to treat BKV-associated hemorrhagic cystitis, a painful side effect associated with immunosuppression from stem cell transplants, may relieve the complication faster in patients with lymphoma or leukemia, according to trial results.

What was very important was that within a week of giving the cells, the majority of patients symptoms improved, Dr. Katy Rezvani, professor of stem cell transplantation and cellular therapy at The University of Texas MD Anderson Cancer Center in Houston and lead study author, said in an interview with CURE. The effect of the cells is relatively rapid.

BKV-associated hemorrhagic cystitis occurs more frequently in patients with leukemia or lymphoma who received a treatment of allogeneic stem cell transplantation. As a result, it can lead to patients having blood in their urine and passing clots, which can cause urinary retention (difficulty urinating or completely emptying the bladder) and, in more severe cases, kidney disease.

In patients who receive stem cell transplants, those who have a half match (when patients only have some genetic similarities with the donors immune system) are at an increased risk for BKV-associated hemorrhagic cystitis because they are more immunosuppressed. Approximately 40% of patients who have a half match develop this complication.

In the phase 2 trial, BKV-specific T cells, which recognize and attack BKV, from healthy donors were given once intravenously, with the option to receive additional doses every two weeks if needed. Of the 59 patients enrolled in the trial, 67.7% had complete (all symptoms resolved) or partial (almost all symptoms resolved) responses within 14 days. This increased to 81.6% after 28 days.

Some intolerance was observed in patients who were previously treated with steroids, which can kill T cells. There were no side effects, and there were no reports of new liver or gastrointestinal graft-versus-host disease (GVHD, occurs when the donor's cells attack the patient's cells) associated with the antiviral T cells, aside from a few cases of skin GVHD that quickly resolved with corticosteroids.

This treatment has the potential to stop the vicious cycle that comes with the current standard of care, which consists of hospitalization with continuous bladder irrigation (using a catheter to wash out the bladder) and morphine infusion to help patients tolerate the pain, according to Rezvani.

This outpatient treatment is preventing patients from having to be admitted (to the hospital), which is wonderful because patients come into hospital with one thing, they stay in the hospital for a few weeks, then they develop other complications, Rezvani explained. They start getting other infections, they get pneumonia, they become malnourished, etc.

According to Rezvani, one donor can produce up to 50 doses of T cells, which are frozen until needed. Every time the patient comes (into the hospital), within 24 hours we can treat them, she said.

Of note, the therapy is only available at MD Anderson, so patients with the complication would need to travel to the health center to receive it an option that may not be possible because of physical condition or finances. Im hoping that we will get to a situation where well be able to start a multicenter study at some point, Rezvani said, which would make the care more accessible to patients. In the meantime, I think the greatest limitation really is that patients will have to come to MD Anderson to receive the treatment, and for many patients with the terrible BKV hemorrhagic cystitis, this is not obviously possible.

Until then, Rezvani is focusing on the next generation of the treatment: genetically modifying BKV-specific T cells that are more resistant to steroids, thus broadening the patient spectrum that the treatment could help.

Its important to realize that the use of immunotherapy against viruses and cancers (has) opened up a very exciting new era of treatment for our patients, she concluded. We are learning a lot more from the immune system (and are harnessing) the power of the immune system to fight infections and cancers. ... I think the field is going to continue to grow, and many more such treatments to target both viruses and cancers (are) going to become available.

For more news on cancer updates, research and education, dont forget tosubscribe to CUREs newsletters here.

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The Power of the Immune System: New Treatment for Painful Blood Cancer Side Effect - Curetoday.com

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Opinions expressed by Entrepreneur contributors are their own.

You're reading Entrepreneur India, an international franchise of Entrepreneur Media.

India is currently home to over 10-plus million pets. Over time, pet parents have realized the importance of medicine and innovation and the change it can bring about in a pets life. Pet innovation today is booming across treats, food, grooming, wearables, insurance, online veterinary services, genetic testing, stem cell therapy, diagnostics and much more. According to PETEX INDIA 2021, the pet food market alone is projected to cross $310 million by FY22. The pet care industry is globally expanding horizontally and vertically with innovative and challenging minds at work. Medical innovation has brought about effective growth thus making way for new products, services and medicines for pets. Medical procedures such as lasers for joint pains and joint care have helped pet owners make the lives of their furry babies a little less painful.

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A few medical innovations in India have particularly taken the Indian pet care sector a notch higher:

CBD & Hemp Seed Oil For Overall Health & Wellness

CBD, or cannabidiol, is a chemical found in the cannabis sativa plant and is known to have wonderful pain-relieving properties. CBD is one of the most effective natural therapies for dogs suffering from arthritis and many other diseases. It is safe and has no side effects. CBD oil interacts with the cells in the muscle, skin and nerves of pets thereby reducing their pain. CBD and hemp seed oils are now available in the form of oil, shampoos and treats. It also benefits pets with anxiety issues triggered due to loud noises, people or travel and keeps them calm and relaxed. CBD oil is finding an innovative use in health and wellness based products for pets and its multiple visible benefits.Omega 3 and Omega 6 fatty acids in hemp seed oil help control skin breakouts and protect the skin.

They are responsible for creating a healthy cell membrane and help to avoid excessive fur shedding. Hemp serves as the optimum plant-based nutrition that is easily digestible and includes antioxidants that aid elevated health in pets. Hemp seed oil has recently been added to pet food and treats and is also being used in healing balms for dry paws and skin.

Prebiotics & Probiotics For Gut Health

Probiotics are the billions of good bacteria that live in the gastrointestinal tract of animals. Pets respond to supplements in the form of immunity boosters and probiotic strips are easy dissolving strips unlike pills, powders or tablets which the pet might refuse to intake. Probiotics treat diarrhoea, stomach related issues, irritable bowel syndrome, improve digestive health, prevent anxiety, reduce stress and improve general health and well-being. Given its health benefits, prebiotics and probiotics have found their way in pet food as they help to maintain the pH balance in the gut and keep the digestive tract healthy. Probiotics have also recently been introduced in shampoos as they help in supporting a healthy microbiome and defend against common skin problems such as itching dryness, dandruff, hot spots, excessive shedding and yeast in pets.

Assistive Devices To Aid Mobility

Harnesses and slings for dogs suffering from hip dysplasia are gaining popularity among vets and pet parents. These act as a wheel-chair and support the pets rear body and enable them to move around. They also help pets who have lost their hind legs in accidents. Harnesses for pets who are blind have been created such that they form a halo around their head and this will alert the pet if they happen to bump against any object. These innovations may alter the pets appearance but what is important is that it helps pets to live a normal life. The same goes for pets afflicted with arthritis. Elevated feeding stations, ramps to reduce the stress on joints have also become common to households who have aging pets.

Veterinary Diagnostics

Innovation in the use of technology that equips veterinarians to view real-time information on internal bone and muscle structure is in the fray. This will help to speed up the prototype required to create an animal bone model that is generated using the tomography scan technology. This technology is building steam though still in its nascent stage. Two new blood types, Langereis and Junior, have been identified in pets apart from the 12 dog blood types. New diagnostic techniques through tests which can help to diagnose the possibility of diseases in pets, confirm or even classify disease status in pets, is the need of the hour.

According to a study by Grand View Research on veterinary medicine, the global veterinary medicine market size was estimated at $29.2 billion in 2020 and is expected to expand at a CAGR of 7.4 per cent from 2021 to 2028. Steady medical innovation is solving unsolved and unattended problems that pets have faced since decades. While the offline gap has been filled in by the online D2C revolution in pet care and wellness, advancements in medical innovation remain unhindered despite the pandemic.

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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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MELVILLE, N.Y., Oct. 26, 2021 (GLOBE NEWSWIRE) -- BioRestorative Therapies, Inc. (BioRestorative or the Company) (OTC: BRTX), a life sciences company focused on stem cell-based therapies, today announced the nomination of two new independent members to its Board of Directors with industry and medical device experience: Patrick F. Williams, Chief Financial Officer at STAAR Surgical, and David Rosa, President and Chief Executive Officer at NeuroOne. Their election to the Board will take effect in the event the Companys pending registration statement becomes effective.

Our new board member nominations represent qualified and diverse executives who bring new perspectives, relevant expertise and leadership experience, positioning BioRestorative to fulfill our mission of bringing cell therapies to patients said Lance Alstodt, Chief Executive Officer of BioRestorative. The addition of Patrick and David is part of a strategic effort to add meaningful leadership experience to BioRestoratives Board of Directors to support the companys focus on driving future growth, enhancing its corporate governance, and creating additional shareholder value.

Patrick F. Williams

Patrick F. Williams has more than 20 years of experience across medical device, consumer product goods and technology sectors. Appointed as Chief Financial Officer of STAAR Surgical Company in July 2020, Mr. Williams is responsible for optimizing the financial performance of STAAR and ensuring the scalability of various functions to support high growth expansion. From 2016 to 2019, he served as the Chief Financial Officer of Sientra, Inc. before transitioning to General Manager for its miraDry business unit. From 2012 to 2016, Mr. Williams served as Chief Financial Officer of ZELTIQ Aesthetics, Inc., a publicly-traded medical device company that was acquired by Allergan. Previously, he served as Vice President in finance, strategy and investor relations roles from 2007 to 2012 at NuVasive, Inc., a San-Diego based medical device company servicing the spine sector. He has also held finance roles with Callaway Golf and Kyocera Wireless. Mr. Williams received an MBA in Finance and Management from San Diego State University and a Bachelor of Arts in Economics from the University of California, San Diego.

David Rosa

DavidRosa has served as the Chief Executive Officer, President and a director of NeuroOne Medical Technologies Corporation, or NeuroOne (Nasdaq: NMTC), since July2017 and served as Chief Executive Officer and a director of NeuroOne, Inc., formerly its wholly-ownedsubsidiary, from October2016 until December2019, when NeuroOne, Inc. merged with and into NeuroOne. NeuroOne is committed to providing minimally invasive and hi-definition solutions for EEG recording, brain stimulation and ablation solutions for patients suffering from epilepsy, Parkinsons disease, dystonia, essential tremors, chronic pain due to failed back surgeries and other related neurological disorders that may improve patient outcomes and reduce procedural costs. From November2009 to November2015, Mr.Rosa served as the Chief Executive Officer and President of Sunshine Heart, Inc., n/k/a Nuwellis, Inc. (Nasdaq: NUWE), a publicly-heldearly-stagemedical device company. From 2008 to November2009, he served as Chief Executive Officer of Milksmart, Inc., a company that specializes in medical devices for animals. From 2004 to 2008, Mr.Rosa served as the Vice President of Global Marketing for Cardiac Surgery and Cardiology at St. Jude Medical, Inc. He serves as a director on the board of directors of Biotricity Inc (Nasdaq: BTCY) and is Chairman of the Board at Neuro Event Labs, a privately held AI-based diagnostics company in Finland.

About BioRestorative Therapies, Inc.

BioRestorative Therapies, Inc. (www.biorestorative.com) develops therapeutic products using cell and tissue protocols, primarily involving adult stem cells. Our two core programs, as described below, relate to the treatment of disc/spine disease and metabolic disorders:

Disc/Spine Program (brtxDISC): Our lead cell therapy candidate, BRTX-100, is a product formulated from autologous (or a persons own) cultured mesenchymal stem cells collected from the patients bone marrow. We intend that the product will be used for the non-surgical treatment of painful lumbosacral disc disorders or as a complementary therapeutic to a surgical procedure. The BRTX-100 production process utilizes proprietary technology and involves collecting a patients bone marrow, isolating and culturing stem cells from the bone marrow and cryopreserving the cells. In an outpatient procedure, BRTX-100 is to be injected by a physician into the patients damaged disc. The treatment is intended for patients whose pain has not been alleviated by non-invasive procedures and who potentially face the prospect of surgery. We have received authorization from the Food and Drug Administration to commence a Phase 2 clinical trial using BRTX-100 to treat chronic lower back pain arising from degenerative disc disease.

Metabolic Program (ThermoStem): We are developing a cell-based therapy candidate to target obesity and metabolic disorders using brown adipose (fat) derived stem cells to generate brown adipose tissue (BAT). BAT is intended to mimic naturally occurring brown adipose depots that regulate metabolic homeostasis in humans. Initial preclinical research indicates that increased amounts of brown fat in animals may be responsible for additional caloric burning as well as reduced glucose and lipid levels. Researchers have found that people with higher levels of brown fat may have a reduced risk for obesity and diabetes.

Forward-Looking Statements

This press release contains "forward-looking statements" within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended, and such forward-looking statements are made pursuant to the safe harbor provisions of the Private Securities Litigation Reform Act of 1995. You are cautioned that such statements are subject to a multitude of risks and uncertainties that could cause future circumstances, events or results to differ materially from those projected in the forward-looking statements as a result of various factors and other risks, including, without limitation, those set forth in the Company's latest Form 10-K filed with the Securities and Exchange Commission. You should consider these factors in evaluating the forward-looking statements included herein, and not place undue reliance on such statements. The forward-looking statements in this release are made as of the date hereof and the Company undertakes no obligation to update such statements.

CONTACT:Email: ir@biorestorative.com

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The scientists, Christopher Rathnam and colleagues, say they have designed a way of controlling the formation of 3D spheroids made from stem cells, while enhancing the spheroids ability to differentiate into functional neurons.

The technology led to an increase in stem cell survival and differentiation two challenges with existing stem cell therapy systems in a mouse model of spinal cord injury, noted the team in a paper published inScience Advances

We believe that our technology platform is an ideal candidate for improving many other types of cell therapies that require high cell survival and effective control of cell fate, making it useful not only for treating [spinal cord injuries] but also for various other diseases and disorders, said the authors.

Although stem cell therapy holds enormous potential for treating debilitating injuries and diseases of the CNS, the team outlined how low survival and inefficient differentiation have restricted its clinical applications.

Recently, 3D cell culture methods, such as stem cellbased spheroids and organoids, have demonstrated advantages by incorporating tissue-mimetic 3D cell-cell interactions, said the experts.

However, a lack of drug and nutrient diffusion, insufficient cell-matrix interactions, and tedious fabrication procedures have compromised their therapeutic effects in vivo, they added.

To address these issues, the Rathnam led team developed a method in which biodegradable manganese dioxide nanosheets guide the rapid assembly of neural stem cells, derived from human induced pluripotent stem cells (iPSCs), into 3D spheroids.

The technique also enables controlled drug release inside the core of the spheroids, which could help to improve cell survival and differentiation, they said.

To evaluate the efficacy of the structures, which they termed synthetic matrix-assisted and rapidly templated (SMART) spheroids, the researchers implanted them at injury sites in a mouse model of spinal cord injury.

As controls, they injected cell suspensions and conventional neurospheres, formed without the use of their novel nanosheets, at the spinal cord injury sites, with the same total number of cells per animal and at the same concentrations.

They found significantly higher cell survival and improved neuronal differentiation efficiency for the SMART neurospheres compared with the controls both 7 days and 1 month after injection.

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Forty years ago,neurologistsand neurobiologistsbelieved that the adult brain became lessplastic and less able to learn and retain new things.Theyhad no idea that non-neuronal cells had anything to do with information processing in the brain, including learning and memory.

Now,afterdecades of researchingand characterizinga particular cell type, called glial cells, in the brain, Akiko Nishiyama, professor of physiology and neurobiology and the new department head,can tell youthatthese cells areessential to enabling humans to learn new tasks well into adulthood, thanks to a very dynamic regulation of the ability of oligodendrocyte precursor cells she had found to generate mature myelin-forming cells. She believes that these cells also play a yet unidentified critical role in the network of brain activity.

We sat down with Nishiyama to talk about her goals for the department and current trends in the growing field of physiology and neurobiology.

What isthephysiology and neurobiology (PNB)majorat UConn?

Physiology is the study of how different parts of the body work, andneurobiology is the study of how the nervous system (brain, spinal cord, and peripheral nerves) works, and this is what I study.ThePNBdepartmentis where faculty andstudentsstudy both disciplines.

In the early- to mid-20th Century, we saw a tremendous expansion of the study of the nervous system, which led to the emergence of a multi-disciplinary field called neurobiology. The name of our department reflects this transition.

How did you get started inneurobiology? Tell us about your research.

I startedmy career in neuropathologyafter finishing six years of medical training.I was curious about how different cells in the nervous system support the function of neurons and how these support cells, known as glial cells, might malfunction in the process of neurodegenerative diseases. Halfway through the residency-doctoral program, I switched to a more basic doctoral program in molecular neurobiology, because I wanted to ask fundamental molecular and cellular questions about how different glial cells in the nervous system interact with neurons.

I sought my postdoctoral training in a lab studying the NG2 protein that seemed to be present in a yet-unidentified subset of glia,andI spent my career characterizing them.

Thirty years later, these cells have become widely known to cellular neurobiologists and have made it into textbooks. My studies established that NG2 cells are precursor cells to oligodendrocytes that make myelin sheaths but are different from stem cells or other known glial cell types.

Now we know these myelin structures are constantly being remodeled as we learn new skills as adults. And if you disrupt the process of the precursor cells, you disrupt the ability to acquire new tasks or learn new motor skills.

Why are these cells important?

We used to think that myelin was formed during the few years after birth and remained stable throughout life.What I found was that oligodendrocyte precursor cells persist in the adult brain and are implicated in some neurological disorders, such as multiple sclerosis.

Thisis an expanding areaof research in a new field called myelin plasticity.Myelin repair is important for the functional repair not only in multiple sclerosis but also after trauma such as spinal cord injury. New genomic studies are emerging that have linked oligodendrocytes to neuropsychiatric and neurodegenerative diseases such as schizophrenia and Parkinsons disease.

What are some of the things you can do with a degree in PNB?

We provide a wide-ranging set of skills, collectively, in the department, because the possibilities grow every day.

Many of our undergraduate students pursue medical, dental, or other health care professions. For instance, we recently developed theInteroperative Neuromonitoring Programwith a masters degree in Surgical Neurophysiology. This program trains specialized medical technologists who monitor the patients muscle and brain activity and other neurophysiologicalindicatorsduring surgery that may be important for surgeons and anesthesiologists to see in real-time.

Some PNB majors go to graduate school to pursue a career in academic or industry research. In addition,students withan advanced degree inphysiology andneurobiology can become teachers or science writers.

Regardless of whether they are pursuing research, we train our undergraduate students to develop a good habit ofidentifying and thinkingthrough a problem. We have faculty with diverse expertise, and our students are introduced to a wide range of questions and approaches to answer them in the classroom as well as in faculty laboratories.

What are some of your goals for the department over the next five years?

Imreally luckyto have astrong andfriendly department. Its a smallenoughdepartment that I can get to knoweach faculty and staff memberquite well.

I would like tobetter connectwith our undergraduate majors early during their time at UConn. Currently, we see them for the first time when they take our gatewayHuman Physiology and Anatomycourse in their sophomore year, and most of our faculty do not see them until they are juniors or seniors. I am interested in exposing freshmen and early sophomores to more experientialtypesof learning, monitoring their progress, and providing feedback and support where needed.

One of the strengths of our department is our facultys research. Many of our faculty, especially the younger faculty, have expanding research programs, have been successful in securing large external grants, and are active in mentoring graduate and undergraduate students in their labs. I would like to provide an environment where the successful faculty can attain an even greater level of excellence and as a department attract a larger number of talented doctoral and postdoctoral trainees to UConn.

I would like to strengthen our graduate program to providemoremultidisciplinary training for the next generation of physiologists andneurobiologiststo gain quantitative and computer skillsas well.

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Two teens developed severe psychiatric symptoms such as paranoia, delusions and suicidal thoughts during mild COVID-19 infections. Now, scientists think they've identified a potential trigger: Rogue antibodies may have mistakenly attacked the teens' brains, rather than the coronavirus.

The researchers spotted these rogue antibodies in two teens who were examined at the University of California, San Francisco (UCSF) Benioff Childrens Hospital after catching COVID-19 in 2020, according to a new report on the cases published Monday (Oct. 25) in the journal JAMA Neurology. The antibodies appeared in the patients' cerebrospinal fluid (CSF), which is a clear liquid that flows in and around the hollow spaces of the brain and spinal cord.

But while such antibodies may attack brain tissue, it's too early to say that these antibodies directly caused the troubling symptoms in the teens, the researchers wrote in the new study. That's because many of the identified antibodies appear to target structures located on the inside of cells, rather than on the outside, co-author Dr. Samuel Pleasure, a physician-scientist and professor of neurology at UCSF, told Live Science in an email.

Related: 20 of the worst epidemics and pandemics in history

"So, we suspect that either the COVID autoantibodies" meaning antibodies that attack the body rather than the virus "are indicative of an out of control autoimmune response that might be driving the symptoms, without the antibodies necessarily causing the symptoms directly," he said. Future studies will be needed to test this hypothesis, and to see whether any other, undiscovered autoantibodies target structures on the surface of cells and thus cause direct damage, he added.

The study's results demonstrate that COVID-19 may trigger the development of brain-targeting autoantibodies, said Dr. Grace Gombolay, a pediatric neurologist at Childrens Healthcare of Atlanta and an assistant professor at Emory University School of Medicine, who wasn't involved in the new study. And they also hint that, in some cases, treatments that "calm down" the immune system may help resolve psychiatric symptoms of COVID-19, she told Live Science in an email.

Both teens in the study received intravenous immunoglobulin, a therapy used to essentially reset the immune response in autoimmune and inflammatory disorders, after which the teens' psychiatric symptoms either partially or completely remitted. But it's possible the patients would have "improved on their own, even without treatment," and this study is too small to rule this out, Gombolay noted.

Other viruses, such as herpes simplex virus, can sometimes drive the development of antibodies that attack brain cells, trigger harmful inflammation and cause neurological symptoms, Gombolay said. "Thus, it is reasonable to suspect that an association could also be seen in COVID-19."

Prior to their research in teens, the study authors published evidence of neural autoantibodies in adult COVID-19 patients. According to a report published May 18 in the journal Cell Reports Medicine, these adult patients experienced seizures, loss of smell and hard-to-treat headaches, and most of them had also been hospitalized due to the respiratory symptoms of COVID-19.

But "in the case of these teens, the patients had quite minimal respiratory symptoms," Pleasure said. This suggests that there's a chance of such symptoms arising during or after cases of mild respiratory COVID-19, Pleasure said.

Over the course of five months in 2020, 18 children and teens were hospitalized at UCSF Benioff Children's Hospital with confirmed COVID-19; the patients tested positive for the virus with either a PCR or rapid antigen test. From this group of pediatric patients, the study authors recruited three teens who underwent neurological evaluations and became the focus for the new case study.

One patient had a history of unspecified anxiety and depression, and after catching COVID-19 they developed signs of delusion and paranoia. The second patient had a history of unspecified anxiety and motor tics, and following infection they experienced rapid mood shifts, aggression and suicidal thoughts; they also experienced "foggy brain," impaired concentration and difficulty completing homework. The third patient, who had no known psychiatric history, was admitted after exhibiting repetitive behaviors, disordered eating, agitation and insomnia for several days, when they hadn't shown these behaviors previously.

As part of their neurological examinations, each teen underwent a spinal tap, where a sample of CSF is drawn from the lower back. All three patients had elevated antibody levels in their CSF, but only the CSF of patients 1 and 2 carried antibodies against SARS-CoV-2, the virus that causes COVID-19. In those two teens, it's possible the virus itself infiltrated their brains and spinal cords, the study authors noted. "I would suspect that if there is direct viral invasion it is transient, but there is still a lot of uncertainty here," Pleasure noted.

These same patients also carried neural autoantibodies in their CSF: In mice, the team found that these antibodies latched onto several areas of the brain, including the brain stem; the cerebellum, located at the very back of the brain; the cortex; and the olfactory bulb, which is involved in smell perception.

The team then used lab-dish experiments to identify the targets the neural antibodies grabbed onto. The researchers flagged a number of potential targets and zoomed in on one in particular: a protein called transcription factor 4 (TCF4). Mutations in the gene for TCF4 can cause a rare neurological disorder called Pitt-Hopkins syndrome, and some studies hint that dysfunctional TCF4 may be involved in schizophrenia, according to a 2021 report in the journal Translational Psychiatry.

These findings hint that the autoantibodies might contribute to a runaway immune response that causes psychiatric symptoms in some COVID-19 patients, but again, the small study cannot prove that the antibodies themselves directly cause disease. It may be that other immune-related factors, apart from the antibodies, drive the emergence of these symptoms.

"These autoantibodies may be most clinically meaningful as markers of immune dysregulation, but we havent found evidence that they are actually causing the patients symptoms. Theres certainly more work to be done in this area," co-first author Dr. Christopher Bartley, an adjunct instructor in psychiatry at the UCSF Weill Institute for Neurosciences, said in a statement.

In future studies, "it would be helpful to examine CSF of children with COVID-19 who did not have neuropsychiatric symptoms," as a point of comparison to those who did, Gombolay said. "However, obtaining CSF from those patients is challenging as CSF has to be obtained by a spinal tap, and a spinal tap is not typically done unless a patient has neurological symptoms."

That said, the team is now collaborating with several groups studying long COVID, who are collecting CSF samples from patients with and without neuropsychiatric symptoms, Pleasure said. "In adults, it is not uncommon to have patients be willing to undergo a spinal tap for research purposes with appropriate informed consent and institutional review." Using these samples, as well as some studies in animal models, the team will work to pinpoint the autoimmune mechanisms behind these troubling neuropsychiatric symptoms, and figure out how autoantibodies fit into that picture.

Originally published on Live Science.

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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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Induced Pluripotent Stem Cells and Their Potential for ...

Cardiac Stem Cells Comments Off on Induced Pluripotent Stem Cells and Their Potential for … | October 16th, 2021

J Cardiovasc Nurs. Author manuscript; available in PMC 2014 Jul 21.

Published in final edited form as:

PMCID: PMC4104807

NIHMSID: NIHMS100185

1Department of Bioengineering, University of Illinois at Chicago

2Department of Physiology and Biophysics and Department of Bioengineering, University of Illinois at Chicago

1Department of Bioengineering, University of Illinois at Chicago

2Department of Physiology and Biophysics and Department of Bioengineering, University of Illinois at Chicago

Stem cells have the ability to differentiate into specific cell types. The two defining characteristics of a stem cell are perpetual self-renewal and the ability to differentiate into a specialized adult cell type. There are two major classes of stem cells: pluripotent that can become any cell in the adult body, and multipotent that are restricted to becoming a more limited population of cells. Cell sources, characteristics, differentiation and therapeutic applications are discussed. Stem cells have great potential in tissue regeneration and repair but much still needs to be learned about their biology, manipulation and safety before their full therapeutic potential can be achieved.

Stem cells have the ability to build every tissue in the human body, hence have great potential for future therapeutic uses in tissue regeneration and repair. In order for cells to fall under the definition of stem cells, they must display two essential characteristics. First, stem cells must have the ability of unlimited self-renewal to produce progeny exactly the same as the originating cell. This trait is also true of cancer cells that divide in an uncontrolled manner whereas stem cell division is highly regulated. Therefore, it is important to note the additional requirement for stem cells; they must be able to give rise to a specialized cell type that becomes part of the healthy animal.1

The general designation, stem cell encompasses many distinct cell types. Commonly, the modifiers, embryonic, and adult are used to distinguish stem cells by the developmental stage of the animal from which they come, but these terms are becoming insufficient as new research has discovered how to turn fully differentiated adult cells back into embryonic stem cells and, conversely, adult stem cells, more correctly termed somatic stem cells meaning from the body, are found in the fetus, placenta, umbilical cord blood and infants.2 Therefore, this review will sort stem cells into two categories based on their biologic properties - pluripotent stem cells and multipotent stem cells. Their sources, characteristics, differentiation and therapeutic applications are discussed.

Pluripotent stem cells are so named because they have the ability to differentiate into all cell types in the body. In natural development, pluripotent stem cells are only present for a very short period of time in the embryo before differentiating into the more specialized multipotent stem cells that eventually give rise to the specialized tissues of the body (). These more limited multipotent stem cells come in several subtypes: some can become only cells of a particular germ line (endoderm, mesoderm, ectoderm) and others, only cells of a particular tissue. In other words, pluripotent cells can eventually become any cell of the body by differentiating into multipotent stem cells that themselves go through a series of divisions into even more restricted specialized cells.

During natural embryo development, cells undergo proliferation and specialization from the fertilized egg, to the blastocyst, to the gastrula during natural embryo development (left side of panel). Pluripotent, embryonic stem cells are derived from the inner cell mass of the blastoctyst (lightly shaded). Multipotent stem cells (diamond pattern, diagonal lines, and darker shade) are found in the developing gastrula or derived from pluripotent stem cells and are restricted to give rise to only cells of their respective germ layer.

Based on the two defining characteristics of stem cells (unlimited self-renewal and ability to differentiate), they can be described as having four outcomes or fates3 (). A common fate for multipotent stem cells is to remain quiescent without dividing or differentiating, thus maintaining its place in the stem cell pool. An example of this is stem cells in the bone marrow that await activating signals from the body. A second fate of stem cells is symmetric self-renewal in which two daughter stem cells, exactly like the parent cell, arise from cell division. This does not result in differentiated progeny but does increase the pool of stem cells from which specialized cells can develop in subsequent divisions. The third fate, asymmetric self-renewal, occurs when a stem cell divides into two daughter cells, one a copy of the parent, the other a more specialized cell, named a somatic or progenitor cell. Asymmetric self-renewal results in the generation of differentiated progeny needed for natural tissue development/regeneration while also maintaining the stem cell pool for the future. The fourth fate is that in which a stem cell divides to produce two daughters both different from the parent cell. This results in greater proliferation of differentiated progeny with a net loss in the stem cell pool.

Four potential outcomes of stem cells. A) Quiescence in which a stem cell does not divide but maintains the stem cell pool. B) Symmetric self-renewal where a stem cell divides into two daughter stem cells increasing the stem cell pool. C) Asymmetric self-renewal in which a stem cell divides into one differentiated daughter cell and one stem cell, maintaining the stem cell pool. D) Symmetric division without self-renewal where there is a loss in the stem cell pool but results in two differentiated daughter cells. (SC- Stem cell, DP-Differentiated progeny)

The factors that determine the fate of stem cells is the focus of intense research. Knowledge of the details could be clinically useful. For example, clinicians and scientists might direct a stem cell population to expand several fold through symmetrical self-renewal before differentiation into multipotent or more specialized progenitor cells. This would ensure a large, homogeneous population of cells at a useful differentiation stage that could be delivered to patients for successful tissue regeneration.

Pluripotent stem cells being used in research today mainly come from embryos, hence the name, embryonic stem cells. Pre-implantation embryos a few days old contain only 10-15% pluripotent cells in the inner cell mass (). Those pluripotent cells can be isolated, then cultured on a layer of feeder cells which provide unknown cues for many rounds of proliferation while sustaining their pluripotency.

Recently, two different groups of scientists induced adult cells back into the pluripotent state by molecular manipulation to yield induced pluripotent stem cells (iPS) that share some of the same characteristics as embryonic stem cells such as proliferation, morphology and gene expression (in the form of distinct surface markers and proteins being expressed).4-8 Both groups used retroviruses to carry genes for transcription factors into the adult cells. These genes are transcribed and translated into proteins that regulate the expression of other genes designed to reprogram the adult nucleus back into its embryonic state. Both introduced the embryonic transcription factors known as Sox2 and Oct4. One group also added Klf4 and c-Myc4, and the other group added Lin28 and Nanog.6 Other combinations of factors would probably also work, but, unfortunately, neither the retroviral carrier method nor the use of the oncogenic transcription factor c-Myc are likely to be approved for human therapy. Consequently, a purely chemical approach to deliver genes into the cells, and safer transcription factors are being tried. Results of these experiments look promising.9

Multipotent stem cells may be a viable option for clinical use. These cells have the plasticity to become all the progenitor cells for a particular germ layer or can be restricted to become only one or two specialized cell types of a particular tissue. The multipotent stem cells with the highest differentiating potential are found in the developing embryo during gastrulation (day 14-15 in humans, day 6.5-7 in mice). These cells give rise to all cells of their particular germ layer, thus, they still have flexibility in their differentiation capacity. They are not pluripotent stem cells because they have lost the ability to become cells of all three germ layers (). On the low end of the plasticity spectrum are the unipotent cells that can become only one specialized cell type such as skin stem cells or muscle stem cells. These stem cells are typically found within their organ and although their differentiation capacity is restricted, these limited progenitor cells play a vital role in maintaining tissue integrity by replenishing aging or injured cells. There are many other sub-types of multipotent stem cells occupying a range of differentiation capacities. For example, multipotent cells derived from the mesoderm of the gastrula undergo a differentiation step limiting them to muscle and connective tissue; however, further differentiation results in increased specialization towards only connective tissue and so on until the cells can give rise to only cartilage or only bone.

Multipotent stem cells found in bone marrow are best known, because these have been used therapeutically since the 1960s10 (their potential will be discussed in greater detail in a later section). Recent research has found new sources for multipotent stem cells of greater plasticity such as the placenta and umbilical cord blood.11 Further, the heart, until recently considered void of stem cells, is now known to contain stem cells with the potential to become cardiac myocytes.12 Similarly, neuro-progenitor cells have been found within the brain.13

The cardiac stem cells are present in such small numbers, that they are difficult to study and their function has not been fully determined. The second review in this series will discuss their potential in greater detail.

Since Federal funding for human embryonic stem cells is restricted in the United States, many scientists use the mouse model instead. Besides their ability to self-renew indefinitely and differentiate into cell types of all three germ layers, murine and human pluripotent stem cells have much in common. It should not be surprising that so many pluripotency traits are conserved between species given the shared genomic sequences and intra-cellular structure in mammals. Both mouse and human cells proliferate indefinitely in culture, have a high nucleus to cytoplasm ratio, need the support of growth factors derived from other live cells, and display similar surface antigens, transcription factors and enzymatic activity (i.e. high alkaline phosphatase activity).14 However, differences between mouse and human pluripotent cells, while subtle, are very important. Although the transcription factors mentioned above to induce pluripotency from adult cells (Oct3/4 and Sox2) are shared, the extracellular signals needed to regulate them differ. Mouse embryonic stem cells need the leukemia inhibitory factor and bone morphogenic proteins while human require the signaling proteins Noggin and Wnt for sustained pluripotency.15 Surface markers used to identify pluripotent cells also differ slightly between the two species as seen in the variants of the adhesion molecule SSEA (SSEA-1 in mouse, SSEA-3 & 4 in humans).16 Thus, while pluripotency research in mouse cells is valuable, a direct correlation to the human therapy is not likely.

Last, but certainly not least, a big difference between mouse and human stem cells are the moral and ethical dilemmas that accompany the research. Some people consider working with human embryonic stem cells to be ethically problematic while very few people have reservations on working with the mouse models. However, given the biological differences between human and mouse cells, most scientists believe that data relevant for human therapy will be missed by working only on rodents.

Cell surface markers are typically also used to identify multipotent stem cells. For example, mesenchymal stem cells can be purified from the whole bone marrow aspirate by eliminating cells that express markers of committed cell types, a step referred to as lineage negative enrichment, and then further separating the cells that express the sca-1 and c-Kit surface markers signifying mesenchymal stem cells. Both the lineage negative enrichment step and the sca-1/c-Kit isolation can be achieved by using flow cytometry and is discussed in further detail in the following review. The c-Kit surface marker also is used to distinguish the recently discovered cardiac stem cells from the rest of the myocardium. A great deal of recent work in cardiovascular research has centered on trying to find which markers indicate early multipotent cells that will give rise to pre-cardiac myocytes. Cells with the specific mesodermal marker, Kdr, give rise to the progenitor cells of the cardiovascular system including contracting cardiac myocytes, endothelial cells and vascular smooth muscle cells and are therefore considered to be the earliest cells with specification towards the cardiovascular lineage.17 Cells at this early stage still proliferate readily and yet are destined to become cells of the cardiovascular system and so may be of great value therapeutically.

Scientists are still struggling to reliably direct differentiation of stem cells into specific cell types. They have used a virtual alphabet soup of incubation factors toward that end (including trying a variety of growth factors, chemicals and complex substrates on which the cells are grown), with, so far, only moderate success. As an example of this complexity, one such approach to achieve differentiation towards cardiac myocytes is to use the chemical activin A and the growth factor BMP-4. When these two factors are administered to pluripotent stem cells in a strictly controlled manner, both in concentration and temporally, increased efficiency is seen in differentiation towards cardiac myocytes, but still, only 30% of cells can be expected to become cardiac.18

Multipotent cells have also been used as the starting point for cell therapy, again with cocktails of growth factors and/or chemicals to induce differentiation toward a specific, desired lineage. Some recipes are simple, such as the use of retinoic acid to induce mesenchymal stem cells into neuronal cells,19 or transforming growth factor- to make bone marrow-derived stem cells express cardiac myocyte markers.20 Others are complicated or ill-defined such as addition of the unknown factors secreted by cells in culture. Physical as well as chemical cues cause differentiation of stem cells. Simply altering the stiffness of the substrate on which cells are cultured can direct stem cells to neuronal, myogenic or osteogenic lineages.21 Cells evolve in physical and chemical environments so a combination of both will probably be necessary for optimal differentiation of stem cells. The importance of physical cues in the cells environment will be discussed in greater detail in the final review of this series. Ideally, for stem cells to be used therapeutically, efficient, uniform protocols must be established so that cells are a well-controlled and well-defined entity.

Pluripotent stem cells have not yet been used therapeutically in humans because many of the early animal studies resulted in the undesirable formation of unusual solid tumors, called teratomas. Teratomas are made of a mix of cell types from all the early germ layers. Later successful animal studies used pluripotent cells modified to a more mature phenotype which limits this proliferative capacity. Cells derived from pluripotent cells have been used to successfully treat animals. For example, animals with diabetes have been treated by the creation of insulin-producing cells responsive to glucose levels. Also, animals with acute spinal cord injury or visual impairment have been treated by creation of new myelinated neurons or retinal epithelial cells, respectively. Commercial companies are currently in negotiations with the FDA regarding the possibility of advancing to human trials. Other animal studies have been conducted to treat several maladies such as Parkinsons disease, muscular dystrophy and heart failure.18,22,23

Scientists hope that stem cell therapy can improve cardiac function by integration of newly formed beating cardiac myocytes into the myocardium to produce greater force. Patches of cardiac myocytes derived from human embryonic stem cells can form viable human myocardium after transplantation into animals,24 with some showing evidence of electrical integration.25,26 Damaged rodent hearts showed slightly improved cardiac function after injection of cardiac myocytes derived from human embryonic stem cells.21 The mechanisms for the gain in function are not fully understood but it may be only partially due to direct integration of new beating heart cells. It is more likely due to paracrine effects that benefit other existing heart cells (see next review).

Multipotent stem cells harvested from bone marrow have been used since the 1960s to treat leukemia, myeloma and lymphoma. Since cells there give rise to lymphocytes, megakaryocytes and erythrocytes, the value of these cells is easily understood in treating blood cancers. Recently, some progress has been reported in the use of cells derived from bone marrow to treat other diseases. For example, the ability to form whole joints in mouse models27 has been achieved starting with mesenchymal stem cells that give rise to bone and cartilage. In the near future multipotent stem cells are likely to benefit many other diseases and clinical conditions. Bone marrow-derived stem cells are in clinical trials to remedy heart ailments. This is discussed in detail in the next review of this series.

Pluripotent and multipotent stem cells have their respective advantages and disadvantages. The capacity of pluripotent cells to become any cell type is an obvious therapeutic advantage over their multipotent kin. Theoretically, they could be used to treat diseased or aging tissues in which multipotent stem cells are insufficient. Also, pluripotent stem cells proliferate more rapidly so can yield higher numbers of useful cells. However, use of donor pluripotent stem cells would require immune suppressive drugs for the duration of the graft28 while use of autologous multipotent stem cells (stem cells from ones self) would not. This ability to use ones own cells is a great advantage of multipotent stem cells. The immune system recognizes specific surface proteins on cells/objects that tell them whether the cell is from the host and is healthy. Autologous, multipotent stem cells have the patients specific surface proteins that allow it to be accepted by the hosts immune system and avoid an immunological reaction. Pluripotent stem cells, on the other hand, are not from the host and therefore, lack the proper signals required to stave off rejection from the immune system. Research is ongoing trying to limit the immune response caused by pluripotent cells and is one possible advantage that iPS cells may have.

The promises of cures for human ailments by stem cells have been much touted but many obstacles must still be overcome. First, more human pluripotent and multipotent cell research is needed since stem cell biology differs in mice and men. Second, the common feature of unlimited cell division shared by cancer cells and pluripotent stem cells must be better understood in order to avoid cancer formation. Third, the ability to acquire large numbers of the right cells at the right stage of differentiation must be mastered. Fourth, specific protocols must be developed to enhance production, survival and integration of transplanted cells. Finally, clinical trials must be completed to assure safety and efficacy of the stem cell therapy. When it comes to stem cells, knowing they exist is a long way from using them therapeutically.

Supported by NIH (HL 62426 and T32 HL 007692)

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Introduction to Stem Cell Therapy

Cardiac Stem Cells Comments Off on Introduction to Stem Cell Therapy | October 16th, 2021

Mesenchymal Stem Cells (MSC), also termed Mesenchymal Stromal Cells, are multipotent cells that can differentiate into a variety of cell types and have the capacity for self renewal. MSC have been shown to differentiate in vitro or in vivo into adipocytes, chondrocytes, osteoblasts, myocytes, neurons, hepatocytes, and pancreatic islet cells. Optimized PromoCell media are available to support both the growth of MSC and their differentiation into several different lineages. Recent experiments suggest that differentiation capabilities into diverse cell types vary between MSC of different origin.

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The cells are tested for their ability to differentiate in vitro into adipocytes, chondrocytes, and osteoblasts. OurhMSC show a verified marker expression profile that complies with ISCT* recommendations, providing well characterized cells.

*ISCT (International Society for Cellular Therapy) Cytotherapy (2006) Vol. 8, No. 4, 315-317

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Cardiac Stem Cells Comments Off on Human Mesenchymal Stem Cells (hMSC) – PromoCell | October 16th, 2021

Abstract

Traumatic spinal cord injury (SCI) is a life changing neurological condition with substantial socioeconomic implications for patients and their care-givers. Recent advances in medical management of SCI has significantly improved diagnosis, stabilization, survival rate and well-being of SCI patients. However, there has been small progress on treatment options for improving the neurological outcomes of SCI patients. This incremental success mainly reflects the complexity of SCI pathophysiology and the diverse biochemical and physiological changes that occur in the injured spinal cord. Therefore, in the past few decades, considerable efforts have been made by SCI researchers to elucidate the pathophysiology of SCI and unravel the underlying cellular and molecular mechanisms of tissue degeneration and repair in the injured spinal cord. To this end, a number of preclinical animal and injury models have been developed to more closely recapitulate the primary and secondary injury processes of SCI. In this review, we will provide a comprehensive overview of the recent advances in our understanding of the pathophysiology of SCI. We will also discuss the neurological outcomes of human SCI and the available experimental model systems that have been employed to identify SCI mechanisms and develop therapeutic strategies for this condition.

Keywords: spinal cord injury, secondary injury mechanisms, clinical classifications and demography, animal models, glial and immune response, glial scar, chondroitin sulfate proteoglycans (CSPGs), cell death

Spinal cord injury (SCI) is a debilitating neurological condition with tremendous socioeconomic impact on affected individuals and the health care system. According to the National Spinal Cord Injury Statistical Center, there are 12,500 new cases of SCI each year in North America (1). Etiologically, more than 90% of SCI cases are traumatic and caused by incidences such as traffic accidents, violence, sports or falls (2). There is a reported male-to-female ratio of 2:1 for SCI, which happens more frequently in adults compared to children (2). Demographically, men are mostly affected during their early and late adulthood (3rd and 8th decades of life) (2), while women are at higher risk during their adolescence (1519 years) and 7th decade of their lives (2). The age distribution is bimodal, with a first peak involving young adults and a second peak involving adults over the age of 60 (3). Adults older than 60 years of age whom suffer SCI have considerably worse outcomes than younger patients, and their injuries usually result from falls and age-related bony changes (1).

The clinical outcomes of SCI depend on the severity and location of the lesion and may include partial or complete loss of sensory and/or motor function below the level of injury. Lower thoracic lesions can cause paraplegia while lesions at cervical level are associated with quadriplegia (4). SCI typically affects the cervical level of the spinal cord (50%) with the single most common level affected being C5 (1). Other injuries include the thoracic level (35%) and lumbar region (11%). With recent advancements in medical procedures and patient care, SCI patients often survive these traumatic injuries and live for decades after the initial injury (5). Reports on the clinical outcomes of patients who suffered SCI between 1955 and 2006 in Australia demonstrated that survival rates for those suffering from tetraplegia and paraplegia is 91.2 and 95.9%, respectively (5). The 40-year survival rate of these individuals was 47 and 62% for persons with tetraplegia and paraplegia, respectively (5). The life expectancy of SCI patients highly depends on the level of injury and preserved functions. For instance, patients with ASIA Impairment Scale (AIS) grade D who require a wheelchair for daily activities have an estimated 75% of a normal life expectancy, while patients who do not require wheelchair and catheterization can have a higher life expectancy up to 90% of a normal individual (6). Today, the estimated life-time cost of a SCI patient is $2.35 million per patient (1). Therefore, it is critical to unravel the cellular and molecular mechanisms of SCI and develop new effective treatments for this devastating condition. Over the past decades, a wealth of research has been conducted in preclinical and clinical SCI with the hope to find new therapeutic targets for traumatic SCI.

SCI commonly results from a sudden, traumatic impact on the spine that fractures or dislocates vertebrae. The initial mechanical forces delivered to the spinal cord at the time of injury is known as primary injury where displaced bone fragments, disc materials, and/or ligaments bruise or tear into the spinal cord tissue (79). Notably, most injuries do not completely sever the spinal cord (10). Four main characteristic mechanisms of primary injury have been identified that include: (1) Impact plus persistent compression; (2) Impact alone with transient compression; (3) Distraction; (4) Laceration/transection (8, 11). The most common form of primary injury is impact plus persistent compression, which typically occurs through burst fractures with bone fragments compressing the spinal cord or through fracture-dislocation injuries (8, 12, 13). Impact alone with transient compression is observed less frequently but most commonly in hyperextension injuries (8). Distraction injuries occur when two adjacent vertebrae are pulled apart causing the spinal column to stretch and tear in the axial plane (8, 12). Lastly, laceration and transection injuries can occur through missile injuries, severe dislocations, or sharp bone fragment dislocations and can vary greatly from minor injuries to complete transection (8). There are also distinct differences between the outcomes of SCI in military and civilian cases. Compared to civilian SCI, blast injury is the common cause of SCI in battlefield that usually involves multiple segments of the spinal cord (14). Blast SCI also results in higher severity scores and is associated with longer hospital stays (15). A study on American military personnel, who sustained SCI in a combat zone from 2001 to 2009, showed increased severity and poorer neurological recovery compared to civilian SCI (15). Moreover, lower lumbar burst fractures and lumbosacral dissociation happen more frequently in combat injuries (1). Regardless of the form of primary injury, these forces directly damage ascending and descending pathways in the spinal cord and disrupt blood vessels and cell membranes (11, 16) causing spinal shock, systemic hypotension, vasospasm, ischemia, ionic imbalance, and neurotransmitter accumulation (17). To date, the most effective clinical treatment to limit tissue damage following primary injury is the early surgical decompression (< 24 h post-injury) of the injured spinal cord (18, 19). Overall, the extent of the primary injury determines the severity and outcome of SCI (20, 21).

Functional classification of SCI has been developed to establish reproducible scoring systems by which the severity of SCI could be measured, compared, and correlated with the clinical outcomes (20). Generally, SCI can be classified as either complete or incomplete. In complete SCI, neurological assessments show no spared motor or sensory function below the level of injury (4). In the past decades, several scoring systems have been employed for clinical classification of neurological deficits following SCI. The first classification system, Frankel Grade, was developed by Frankel and colleagues in 1969 (22). They assessed the severity and prognosis of SCI using numerical sensory and motor scales (22). This was a 5-grade system in which Grade A was the most severe SCI with complete loss of sensory and motor function below the level of injury. Grade B represented complete motor loss with preserved sensory function and sacral sparing. Patients in Grade C and D had different degrees of motor function preservation and Grade E represented normal sensory and motor function. The Frankel Grade was widely utilized after its publication due to its ease of use. However, lack of clear distinction between Grades C and D and inaccurate categorization of motor improvements in patients over time, led to its replacement by other scoring systems (20).

Other classification methods followed Frankel's system. In 1987, Bracken et al. at Yale University School of Medicine classified motor and sensory functions separately in a 5 and 7-scale systems, respectively (23). However, this scoring system failed to account for sacral function (20). Moreover, integration of motor and sensory classifications was impossible in this system and it was abandoned due to complexity and impracticality in clinical settings (20). Several other scoring systems were developed in 1970' and 1980's by different groups such as Lucas and Ducker at the Maryland Institute for Emergency Medical Services in late 1970's (24), Klose and colleagues at the University of Miami Neuro-spinal Index (UMNI) in early 1980s (25) and Chehrazi and colleagues (Yale Scale) in 1981 (26). These scoring systems also became obsolete due to their disadvantage in evaluation of sacral functions, difficulty of use or discrepancies between their motor and sensory scoring sub-systems (20).

The ASIA scoring system is currently the most widely accepted and employed clinical scoring system for SCI. ASIA was developed in 1984 by the American Spinal Cord Injury Association and has been updated over time to improve its reliability (). In this system, sensory function is scored from 02 and motor function from 0 to 5 (20). The ASIA impairment score (AIS) ranges from complete loss of sensation and movement (AIS = A) to normal neurological function (AIS = E). The first step in ASIA system is to identify the neurological level of injury (NLI). In this assessment, except upper cervical vertebrae that closely overlay the underlying spinal cord segments, the anatomical relationship between the spinal cord segments and their corresponding vertebra is not reciprocally aligned along the adult spinal cord (20). At thoracic and lumbar levels, each vertebra overlays a spinal cord segment one or two levels below and as the result, a T11 vertebral burst fracture results in neurological deficit at and below L1 spinal cord segment. Hence, the neurological level of injury (NLI) is defined as the most caudal neurological level at which all sensory and motor functions are normal (20). Upon identifying the NLI, if the injury is complete (AIS = A), zone of partial preservation (ZPP) is determined (20). ZPP is defined as all the segments below the NLI that have some preserved sensory or motor function. A precise record of ZPP enables the examiners to distinguish spontaneous from treatment-induced functional recovery, thus, essential for evaluating the therapeutic efficacy of treatments (20). Complete loss of motor and preservation of some sensory functions below the neurological level of the injury is categorized as AIS B (20). If motor function is also partially spared below the level of the injury, AIS score can be C or D (20). The AIS is scored D when the majority of the muscle groups below the level of the injury exhibit strength level of 3 or higher (for more details see ). ASIA classification combines the assessments of motor, sensory and sacral functions, thus addressing the shortcomings of previous scoring systems (20). The validity and reproducibility of ASIA system combined with its accuracy in prediction of patients' outcome have made it the most accepted and reliable clinical scoring system utilized for neurological classification of SCI (20).

ASIA scoring for the neurological classification of the SCI. A sample scoring sheet used for ASIA scoring in clinical setting is provided (adopted from: http://asia-spinalinjury.org).

In clinical management of SCI, neurological outcomes are generally determined at 72 h after injury using ASIA scoring system (20, 27). This time-point has shown to provide a more precise assessment of neurological impairments after SCI (28). One important predictor of functional recovery is to determine whether the injury was incomplete or complete. As time passes, SCI patients experience some spontaneous recovery of motor and sensory functions. Most of the functional recovery occurs during the first 3 months and in most cases reaches a plateau by 9 months after injury (20). However, additional recovery may occur up to 1218 months post-injury (20). Long term outcomes of SCI are closely related to the level of the injury, the severity of the primary injury and progression of secondary injury, which will be discussed in this review.

Depending on the level of SCI, patients experience paraplegia or tetraplegia. Paraplegia is defined as the impairment of sensory or motor function in lower extremities (27, 28). Patients with incomplete paraplegia generally have a good prognosis in regaining locomotor ability (~76% of patients) within a year (27). Complete paraplegic patients, however, experience limited recovery of lower limb function if their NLI is above T9 (29). An NLI below T9 is associated with 38% chance of regaining some lower extremity function (29). In patients with complete paraplegia, the chance of recovery to an incomplete status is only 4% with only half of these patients regaining bladder and bowel control (29). Tetraplegia is defined as partial or total loss of sensory or motor function in all four limbs. Patients with incomplete tetraplegia will gain better recovery than complete tetra- and paraplegia (30). Unlike complete SCI, recovery from incomplete tetraplegia usually happens at multiple levels below the NLI (20). Patients generally reach a plateau of recovery within 912 months after injury (20). Regaining some motor function within the first month after the injury is associated with a better neurological outcome (20). Moreover, appearance of muscle flicker (a series of local involuntary muscle contractions) in the lower extremities is highly associated with recovery of function (31). Patients with complete tetraplegia, often (6690%) regain function at one level below the injury (28, 30). Importantly, initial muscle strength is an important predictor of functional recovery in these patients (20). Complete tetraplegic patients with cervical SCI can regain antigravity muscle function in 27% of the cases when their initial muscle strength is 0 on a 5-point scale (32). However, the rate of regaining antigravity muscle strength at one caudal level below the injury increases to 97% when the patients have initial muscle strength of 12 on a 5-point scale (33).

An association between sensory and motor recovery has been demonstrated in SCI where spontaneous sensory recovery usually follows the pattern of motor recovery (20, 34). Maintenance of pinprick sensation at the zone of partial preservation or in sacral segments has been shown as a reliable predictor of motor recovery (35). One proposed reason for this association is that pinprick fibers in lateral spinothalamic tract travel in proximity of motor fibers in the lateral corticospinal tract, and thus, preservation of sensory fibers can be an indicator of the integrity of motor fiber (20). Diagnosis of an incomplete injury is of great importance and failure to detect sensory preservation at sacral segments results in an inaccurate assessment of prognosis (20).

In the past few decades, various animal models have been developed to allow understanding the complex biomedical mechanisms of SCI and to develop therapeutic strategies for this condition. An ideal animal model should have several characteristics including its relevance to the pathophysiology of human SCI, reproducibility, availability, and its potential to generate various severities of injury (36).

Small rodents are the most frequently employed animals in SCI studies due to their availability, ease of use and cost-effectiveness compared to primates and larger non-primate models of SCI (36, 37). Among rodents, rats more closely mimic pathophysiological, electrophysiological, functional, and morphological features of non-primate and human SCI (38). In rat (39), cat (40), monkey (41), and human SCI (17), a cystic cavity forms in the center of the spinal cord, which is a surrounded by a rim of anatomically preserved white matter. A study by Metz and colleagues compared the functional and anatomical outcomes of rat contusive injuries and human chronic SCI (42). High resolution MRI assessments identified that SCI-induced neuroanatomical changes such as spinal cord atrophy and size of the lesion were significantly correlated with the electrophysiological and functional outcomes in both rat and human contusive injuries (42). Histological assessments in rats also showed a close correlation between the spared white matter and functional preservation following injury (42). These studies provide evidence that rat models of contusive SCI could serve as an adequate model to develop and evaluate the structural and functional benefits of therapeutic strategies for SCI (42).

Mice show different histopathology than human SCI in which the lesion site is filled with dense fibrous connective-like tissue (4346). Mouse SCI studies show the presence of fibroblast-like cells expressing fibronectin, collagen, CD11b, CD34, CD13, and CD45 within the lesion core of chronic SCI, while it is absent in the injured spinal cord of rats (47). Another key difference between rat and mice SCI is the time-point of inflammatory cell infiltration. While microglia/macrophage infiltration is relatively consistent between rat and mouse models of SCI (47), there is a temporal difference in infiltration of neutrophils and T cells between the two species (47, 48). In SCI rats, infiltration of neutrophils, the first responders, peaks at 6 h post injury, followed by a significant decline at 2448 h after SCI (48). Similarly, in mouse SCI, neutrophil infiltration occurs within 6 h following injury; however, their numbers continue to rise and do not peak until 314 days post injury (49). T cell infiltration also varies between rat and mouse SCI models (50). In rats, T cell infiltration occurs between 3 and 7 days post injury and declines by 50% in the following 2 weeks (47), whereas in mice, T cell infiltration is not detected until 14 days post injury and their number doubles between 2 and 6 weeks post injury (47). Regardless of their pathophysiological relevance, mice have been used extensively in SCI studies primarily due to the availability of transgenic and mutant mouse models that have allowed uncovering molecular and cellular mechanisms of SCI (38).

In recent years, there has been emerging interest in employment of non-human primates and other larger animals such as pig, dog and cat as intermediate pre-clinical models (5153) to allow more effective translation of promising treatments from rodent models to human clinical trials (50). Although rodents have served as invaluable models for studying SCI mechanisms and therapeutic development, larger mammals, in particular non-human primates, share a closer size, neuroanatomy, and physiology to humans. Importantly, their larger size provides a more relevant platform for drug development, bioengineering inventions, and electrophysiological and rehabilitation studies. Nonetheless, both small and large animal models of SCI have limitations in their ability to predict the outcome in human SCI. One important factor is high degree of variability in the nature of SCI incidence, severity and location of the injury in human SCI, while in laboratory animal models, these variabilities are less (36). Values acquired by clinical scoring systems such as ASIA or Frankel scoring systems lack the consistency of the data acquired from laboratory settings, which makes the translation of therapeutic interventions from experimental to clinical settings challenging (36). A significant effect from an experimental treatment in consistent laboratory settings may not be reproducible in clinical settings due to high variability and heterogeneity in human populations and their injuries (36). To date, several pharmacological and cellular preclinical discoveries have led to human clinical trials based on their efficacy in improving the outcomes of SCI in small animal models. However, the majority of these trials failed to reproduce the same efficacy in human SCI. Thus, in pre-clinical studies, animal models, and study designs should be carefully chosen to reflect the reality of clinical setting as closely as possible (36). Larger animals provide the opportunity to refine promising therapeutic strategies prior to testing in human SCI; however, their higher cost, need for specialized facilities and small subject (sample) size have limited their use in SCI research (50). Thus, rodents are currently the most commonly employed models for preclinical discoveries and therapeutic development, while the use of larger animals is normally pursued for late stage therapies that have shown efficacy and promise in small animal models. provides a summary of available SCI models.

Animal models are also classified based on the type of SCI. The following sections will provide an overview on the available SCI models that are developed based on injury mechanisms, their specifications and relevance to human SCI ().

A complete transection model of SCI is relatively easy to reproduce (51). However, this model is less relevant to human SCI as a complete transection of the spinal cord rarely happens (51). While they do not represent clinical reality of SCI, transection models are specifically suitable for studying axonal regeneration or developing biomaterial scaffolds to bridge the gap between proximal and distal stamps of the severed spinal cord (51). Due to complete disconnection from higher motor centers, this model is also suitable for studying the role of propriospinal motor and sensory circuits in recovery of locomotion following SCI (51, 80). Partial transection models including hemi-section, unilateral transection and dorsal column lesions are other variants of transection models (51). Partial transection models are valuable for investigation of nerve grafting, plasticity and where a comparison between injured and non-injured pathways is needed in the same animal (51). However, these models lead to a less severe injury and higher magnitude of spontaneous recovery rendering them less suitable for development and evaluation of new therapies (51).

Contusion is caused by a transient physical impact to the spinal cord and is clinically-relevant. There are currently three types of devices that can produce contusion injury in animal models: weight-drop apparatus, electromagnetic impactor, and a recently introduced air gun device (51). The impactor model was first introduced by Gruner at New York University (NYU) in 1992 (81). The original NYU impactor included a metal rod of specific weight (10 g) that could be dropped on the exposed spinal cord from a specific height to induce SCI (51). This model allowed induction of a defined severity of SCI by adjusting the height, which the rod fell on the spinal cord (81). Parameters such as time, velocity at impact and biomechanical response of the tissue can be recorded for analysis and verification (51). The NYU impactor was later renamed to Multicenter Animal Spinal Cord Injury Study (MASCIS) impactor, and conditions surrounding the study and use of the MASCIS impactor were standardized (51). Since its introduction, the MASCIS impactor has been updated twice. The most recent version, MACIS III, was introduced in 2012 and included both electromagnetic control and digital recording of the impact parameters (51). However, inability to control duration of impact and weight bounce, that could cause multiple impacts, have been known limitations of MASCIS impactors (51).

The Infinite Horizon (IH) impactor is another type of impactor that utilizes a stepping motor to generate force-controlled impact in contrast to free fall in the MASICS impactor (51). This feature allows for better control over the force of impact and prevents weight bounce as the computer-controlled metal impounder can be immediately retracted upon transmitting a desired force to the spinal cord (51). IH impactor can be set to different force levels to provide mild, moderate and severe SCI in rats (ex. 100, 150, and 200 kdyn) (51). A limitation with IH impactors is unreliability of their clamps in holding the spinal column firmly during the impact that can cause inconsistent parenchymal injury and neurological deficits (51).

Ohio State University (OSU) impactor is a computer controlled electromagnetic impactor that was originally invented in 1987 and refined in 1992 to improve reliability (58). As the OSU impactor is electromagnetically controlled, multiple strikes are avoided (51). Subsequently, a modified version of the OSU impactor was developed in 2000 for use in mice (43). However, the OSU impactor is limited by its inability to determine the precise initial contact point with the spinal cord due to displacement of CSF upon loading the device (51). To date, MASCIS, IH and OSU impactor devices have been employed extensively and successfully to induce SCI. These impactor devices are available for small and large animals such as mice, rats, marmosets, cats, and pigs (51, 82).

Compressive models of SCI have been also employed for several decades (61). While contusion injury is achieved by applying a force for a very brief period (milliseconds), the compression injury consists of an initial contusion for milliseconds followed by a prolonged compression through force application for a longer duration (seconds to minutes) (51). Thus, compression injury can be categorized as contusive-compressive models (51). Various models of compressive SCI are available.

Clip compression is the most commonly used compression model of SCI in rat and mice (51, 61, 62, 83). It was first introduced by Rivlin and Tator in 1978 (61). In this model, following laminectomy, a modified aneurism clip with a calibrated closing force is applied to the spinal cord for a specific duration of time (usually 1 min) to induce a contusive-compressive injury (51). The severity of injury can be calibrated and modified by adjusting the force of the clip and the duration of compression (51). For example, applying a 50 g clip for 1 min typically produces a severe SCI, while a 35 g clip creates a moderate to severe injury with the same duration (83). Aneurysm clips were originally designed for use in rat SCI, however, in recent years smaller and larger clips have been developed to accommodate its use in mice (62) and pig models (52). The clip compression model has several advantages compared to contusion models. This method is less expensive and easier to perform (51). Importantly, in contrast to the impactor injury that contusion is only applied dorsally to the spinal cord, the clip compression model provides contusion and compression simultaneously both dorsally and ventrally. Hence, clip compression model more closely mimics the most common form of human SCI, which is primarily caused by dislocation and burst compression fractures (83). Despite its advantages, clip compression model can create variabilities such as the velocity of closing and actual delivered force that cannot be measured precisely at the time of application (51).

Calibrated forceps compression has been also employed to induce SCI in rodents. This simple and inexpensive compressive model was first utilized in 1991 for induction of SCI in guinea pigs (64). In this method, a calibrated forceps with a spacer is used to compress the spinal cord bilaterally (51). This model lacks the initial impact and contusive injury, which is associated with most cases of human traumatic SCI. Accordingly, this model is not a clinically relevant model for reproducing human SCI pathology and therapeutic development (51).

Balloon Compression model has been also utilized extensively in primates and larger animals such as dogs and cats (8486). In this model, a catheter with an inflatable balloon is inserted in the epidural or subdural space. The inflation of the balloon with air or saline for a specific duration of time provides the force for induction of SCI (51). Generally, all compression models (clip, forceps, and balloon) have the same limitation as the velocity and amount of force are unmeasurable (51).

In conclusion, while existing animal models do not recapitulate all clinical aspects of human SCI, the compression and contusion models are considered to be the most relevant and commonly employed methods for understanding the secondary injury mechanisms and therapeutic development for SCI.

Secondary injury begins within minutes following the initial primary injury and continues for weeks or months causing progressive damage of spinal cord tissue surrounding the lesion site (7). The concept of secondary SCI was first introduced by Allen in 1911 (87). While studying SCI in dogs, he observed that removal of the post traumatic hematomyelia improved neurological outcome. He hypothesized that presence of some biochemical factors in the necrotic hemorrhagic lesion causes further damage to the spinal cord (87). The term of secondary injury is still being used in the field and is referred to a series of cellular, molecular and biochemical phenomena that continue to self-destruct spinal cord tissue and impede neurological recovery following SCI () (20).

Summary of secondary injury processes following traumatic spinal cord injury. Diagram shows the key pathophysiological events that occur after primary injury and lead to progressive tissue degeneration. Vascular disruption and ischemia occur immediately after primary injury that initiate glial activation, neuroinflammation, and oxidative stress. These acute changes results in cell death, axonal injury, matrix remodeling, and formation of a glial scar.

Secondary injury can be temporally divided into acute, sub-acute, and chronic phases. The acute phase begins immediately following SCI and includes vascular damage, ionic imbalance, neurotransmitter accumulation (excitotoxicity), free radical formation, calcium influx, lipid peroxidation, inflammation, edema, and necrotic cell death (7, 20, 88). As the injury progresses, the sub-acute phase of injury begins which involves apoptosis, demyelination of surviving axons, Wallerian degeneration, axonal dieback, matrix remodeling, and evolution of a glial scar around the injury site (). Further changes occur in the chronic phase of injury including the formation of a cystic cavity, progressive axonal die-back, and maturation of the glial scar (7, 8992). Here, we will review the key components of acute secondary injury that contribute to the pathophysiology of SCI (, ).

Pathophysiology of traumatic spinal cord injury. This schematic diagram illustrates the composition of normal and injured spinal cord. Of note, while these events are shown in one figure, some of the pathophysiological events may not temporally overlap and can occur at various phases of SCI, which are described here. Immediately after primary injury, activation of resident astrocytes and microglia and subsequent infiltration of blood-borne immune cells results in a robust neuroinflammatory response. This acute neuroinflammatory response plays a key role in orchestrating the secondary injury mechanisms in the sub-acute and chronic phases that lead to cell death and tissue degeneration, as well as formation of the glial scar, axonal degeneration and demyelination. During the acute phase, monocyte-derived macrophages occupy the epicenter of the injury to scavenge tissue debris. T and B lymphocytes also infiltrate the spinal cord during sub-acute phase and produce pro-inflammatory cytokines, chemokines, autoantibodies reactive oxygen and nitrogen species that contribute to tissue degeneration. On the other hand, M2-like macrophages and regulatory T and B cells produce growth factors and pro-regenerative cytokines such as IL-10 that foster tissue repair and wound healing. Loss of oligodendrocytes in acute and sub-acute stages of SCI leads to axonal demyelination followed by spontaneous remyelination in sub-acute and chronic phases. During the acute and sub-acute phases of SCI; astrocytes, OPCs and pericytes, which normally reside in the spinal cord parenchyma, proliferate and migrate to the site of injury and contribute to the formation of the glial scar. The glial scar and its associated matrix surround the injury epicenter and create a cellular and biochemical zone with both beneficial and detrimental roles in the repair process. Acutely, the astrocytic glial scar limits the spread of neuroinflammation from the lesion site to the healthy tissue. However, establishment of a mature longstanding glial scar and upregulation of matrix chondroitin sulfate proteoglycans (CSPGs) are shown to inhibit axonal regeneration/sprouting and cell differentiation in subacute and chronic phases.

Disruption of spinal cord vascular supply and hypo-perfusion is one of the early consequences of primary injury (93). Hypovolemia and hemodynamic shock in SCI patients due to excessive bleeding and neurogenic shock result in compromised spinal cord perfusion and ischemia (93). Larger vessels such as anterior spinal artery usually remain intact (94, 95), while rupture of smaller intramedullary vessels and capillaries that are susceptible to traumatic damage leads to extravasation of leukocytes and red blood cells (93). Increased tissue pressure in edematous injured spinal cord and hemorrhage-induced vasospasm in intact vessels further disrupts blood flow to the spinal cord (93, 95). In rat and monkey models of SCI, there is a progressive reduction in blood flow at the lesion epicenter within the first few hours after injury which remains low for up to 24 h (96). The gray matter is more prone to ischemic damage compared to the white matter as it has a 5-fold higher density of capillary beds and contains neurons with high metabolic demand (95, 97, 98). After injury, white matter blood flow typically returns to normal levels within 15 min post injury, whereas there are multiple hemorrhages in the gray matter and as a result, re-perfusion usually does not occur for the first 24 h (9, 99, 100). Vascular insult, hemorrhage and ischemia ultimately lead to cell death and tissue destruction through multiple mechanisms, including oxygen deprivation, loss of adenosine triphosphate (ATP), excitotoxicity, ionic imbalance, free radical formation, and necrotic cell death. Cellular necrosis and release of cytoplasmic content increase the extracellular level of glutamate causing glutamate excitotoxicity (93, 101). Moreover, re-establishment of blood flow in ischemic tissue leads to further damage through generating free radicals and eliciting an inflammatory response (93, 102) that will be discussed in this review.

Within few minutes after primary SCI, the combination of direct cellular damage and ischemia/hypoxia triggers a significant rise of extracellular glutamate, the main excitatory neurotransmitter in the CNS (7). Glutamate binds to ionotropic (NMDA, AMPA, and Kainate receptors) as well as metabotropic receptors resulting in calcium influx inside the cells (103105) (93). The effect of glutamate is not restricted to neurons as its receptors are vastly expressed on the surface of all glia and endothelial cells (103106). Astrocytes can also release excess glutamate extracellularly upon elevation of their intracellular Ca2+ levels. Reduced ability of activated astrocytes for glutamate re-uptake from the interstitial space due to lipid peroxidation results in further accumulation of glutamate in the SCI milieu (93). Using microdialysis, elevated levels of glutamate have been detected in the white matter in the acute stage of injury (107). Based on a study by Panter and colleagues, glutamate increase is detected during the first 2030 min post SCI and returns to the basal levels after 60 min (108).

Under normal condition, concentration of free Ca2+ can considerably vary in different parts of the cell (109). In the cytosol, Ca2+ ranges from 50100 nM while it approaches 0.51.0 mM in the lumen of endoplasmic reticulum (110112). A long-lasting abnormal increase in Ca2+ concentration in cytosol, mitochondria or endoplasmic reticulum has detrimental consequences for the cell (109113). Mitochondria play a central role in calcium dependent neuronal death (113). In neurons, during glutamate induced excitotoxicity, NMDA receptor over-activity leads to mitochondrial calcium overload, which can cause apoptotic or necrotic cell death (113). Shortly after SCI, Ca2+ enters mitochondria through the mitochondrial calcium uniporter (MCU) (114). While the amount of mitochondrial calcium is limited during the resting state of a neuron, they can store a high amount of Ca2+ following stimulation (113). Calcium overload also activates a host of protein kinases and phospholipases that results in calpain mediated protein degradation and oxidative damage due to mitochondrial failure (93). In the injured white matter, astrocytes, oligodendrocytes and myelin are also damaged by the increased release of glutamate and Ca2+-dependent excitotoxicity (115). Within the first few hours after injury, oligodendrocytes show signs of caspase-3 activation and other apoptotic features, and their density declines (116). Interestingly, while glutamate excitotoxicity is triggered by ionic imbalance in the white matter, in the gray matter, it is largely associated with the activity of neuronal NMDA receptors (117, 118). Altogether, activation of NMDA receptors and consequent Ca2+ overload appears to induce intrinsic apoptotic pathways in neurons and oligodendrocytes and causes cell death in the first week of SCI in the rat (119, 120). Administration of NMDA receptor antagonist (MK-801) shortly following SCI has been associated with improved functional recovery and reduced edema (121).

Mitochondrial calcium overload also impedes mitochondrial respiration and results in ATP depletion disabling Na+/K+ ATPase and increasing intracellular Na+ (119, 122124). This reverses the function of the Na+ dependent glutamate transporter that normally utilizes Na+ gradient to transfer glutamate into the cells (119, 125, 126). Moreover, the excess intracellular Na+ reverses the activity of Na+/Ca2+ exchanger allowing more Ca+ influx (127). Cellular depolarization activates voltage gated Na+ channels that results in entry of Cl and water into the cells along with Na+ causing swelling and edema (128). Increased Na+ concentration over-activates Na+/H+ exchanger causing a rise in intracellular H+ (101, 129). Resultant intracellular acidosis increases membrane permeability to Ca2+ that exacerbates the injury-induced ionic imbalance (101, 129). Axons are more susceptible to the damage caused by ionic imbalance due to their high concentration of voltage gated Na+ channels in the nodes of Ranvier (7). Accumulating evidence shows that administration of Na+ channel blockers such as Riluzole attenuates tissue damage and improves functional recovery in SCI underlining sodium as a key player in secondary injury mechanisms (130133).

SCI results in production of free radicals and nitric oxide (NO) (114). Mitochondrial Ca2+ overload activates NADPH oxidase (NOX) and induces generation of superoxide by electron transport chain (ETC) (114). Reactive oxygen and nitrogen species (ROS and RNS) produced by the activity of NOX and ETC activates cytosolic poly (ADP ribose) polymerase (PARP). PARP consumes and depletes NAD+ causing failure of glycolysis, ATP depletion and cell death (114). Moreover, PAR polymers produced by PARP activity, induce the release of apoptosis inducing factor (AIF) from mitochondria and induce cell death (114). On the other hand, acidosis caused by SCI results in the release of intracellular iron from ferritin and transferrin (93). Spontaneous oxidation of Fe2+ to Fe3+ gives rise to more superoxide radicals (93). Subsequently, the Fenton reaction between Fe3+ and hydrogen peroxide produces highly reactive hydroxyl radicals (134). The resultant ROS and RNS react with numerous targets including lipids in the cell membrane with the most deleterious effects (93, 135). Because free radicals are short-lived and difficult to assess, measurements of their activity and final products, such as Malondialdehyde (MDA), are more reliable following SCI. Current evidence indicates that MDA levels are elevated as early as 1 h and up to 1 week after SCI (136, 137).

Oxidation of lipids and proteins is one of the key mechanisms of secondary injury following SCI (93). Lipid peroxidation starts when ROSs interact with polyunsaturated fatty acids in the cell membrane and generate reactive lipids that will then form lipid peroxyl radicals upon interacting with free superoxide radicals (138, 139). Each lipid peroxyl radical can react with a neighboring fatty acid, turn it into an active lipid and start a chain reaction that continues until no more unsaturated lipids are available or terminates when the reactive lipid quenches with another radical (93). The final products of this termination step of the lipid peroxidation is 4-hydroxynonenal (HNE) and 2-propenal, which are highly toxic to the cells (138140). Lipid peroxidation is also an underlying cause of ionic imbalance through destabilizing cellular membranes such as cytoplasmic membrane and endoplasmic reticulum (93). Moreover, lipid peroxidation leads to Na+/K+ ATPase dysfunction that exacerbates the intracellular Na+ overload (141). In addition to ROS associated lipid peroxidation, amino acids are subject to significant RNS associated oxidative damage following SCI (93). RNSs (containing ONOO) can nitrate the tyrosine residues of amino acids to form 3-nitrotyrosine (3-NT), a marker for peroxynitrite (ONOO) mediated protein damage (139). Lipid and protein oxidation following SCI has a number of detrimental consequences at cellular level including mitochondrial respiratory and metabolic failure as well as DNA alteration that ultimately lead to cell death (141).

Cell death is a major event in the secondary injury mechanisms that affects neurons and glia after SCI (142145). Cell death can happen through various mechanisms in response to various injury-induced mediators. Necrosis and apoptosis were originally identified as two major cell death mechanisms following SCI (146148). However, recent research has uncovered additional forms of cell death. In 2012, the Nomenclature Committee on Cell Death (NCCD) NCCD defined 12 different forms of cell death such as necroptosis, pyroptosis, and netosis (149). Among the identified modes of cell death, to date, necrosis, necroptosis, apoptosis, and autophagy have been studied more extensively in the context of SCI and will be discussed in this review.

Following SCI, neurons and glial cells die through necrosis as the result of mechanical damage at the time of primary injury that also continues to the acute and subacute stages of injury (7, 150). Necrosis occurs due to a multitude of factors including accumulation of toxic blood components (151), glutamate excitotoxicity and ionic imbalance (152), ATP depletion (153), pro-inflammatory cytokine release by neutrophils and lymphocytes (154, 155), and free radical formation (142, 156158). It was originally thought that necrosis is caused by a severe impact on a cell that results in rapid cell swelling and lysis. However, follow up evidence showed that in the case of seizure, ischemia and hypoglycemia, necrotic neurons show signs of shrunken, pyknotic, and condensed nuclei, with swollen, irreversibly damaged mitochondria and plasma membrane that are surrounded by astrocytic processes (159). Moreover, necrosis was conventionally viewed as instantaneous energy-independent non-programmed cell death (142, 156). However, recent research has identified another form of necrosis, termed as necroptosis, that is executed by regulated mechanisms.

Programmed necrosis or necroptosis has been described more recently as a highly regulated, caspase-independent cell death with similar morphological characteristics as necrosis (160). Necroptosis is a receptor-mediated process. It is induced downstream of the TNF receptor 1 (TNFR1) and is dependent on the activity of the receptor interacting protein kinase 1 (RIPK1) and RIPK3. Recent studies has uncovered a key role for RIPK1 as the mediator of necroptosis and a regulator of the innate immune response involved in both inflammation and cell death (161). Evidence from SCI studies show that lysosomal damage can potentiate necroptosis by promoting RIPK1 and RIPK3 accumulation (161). Interestingly, inhibition of necroptosis by necrostatin-1, a RIPK1 inhibitor, improves functional outcomes after SCI (150). These initial findings suggest that modulation of necroptosis pathways seems to be a promising target for neuroprotective strategies after SCI.

Apoptosis is the most studied mechanism of cell death after SCI. Apoptosis represents a programmed, energy dependent mode of cell death that begins within hours of primary injury (7). This process takes place in cells that survive the primary injury but endure enough insult to activate their apoptotic pathways (142). In apoptosis, the cell shrinks and is eventually phagocytosed without induction of an inflammatory response (156). Apoptosis typically occurs in a delayed manner in areas more distant to the injury site and most abundantly affects oligodendrocytes. In rat SCI, apoptosis happens as early as 4 h after the injury and reaches a peak at 7 day (156). At the site of injury majority of oligodendrocytes are lost within 7 days after SCI (162). However, apoptosis can be observed at a diminished rate for weeks after SCI (162, 163). Microglia and astrocytes also undergo apoptosis (156, 164). Interestingly, apoptotic cell death occurs in the chronically injured spinal cord in rat, monkey and human models of SCI, which is thought to be due to loss of trophic support from degenerating axons (146, 165).

Apoptosis is induced through extrinsic and intrinsic pathways based on the triggering mechanism (166). The extrinsic pathway is triggered by activation of death receptors such as FAS and TNFR1, which eventually activates caspase 8 (167). The intrinsic pathway, however, is regulated through a balance between intracellular pro- and anti-apoptotic proteins and is triggered by the release of cytochrome C from mitochondria and activating caspase 9 (167). In SCI lesion, apoptosis primarily happens due to injury induced Ca2+ influx, which activates caspases and calpain; enzymes involved in breakdown of cellular proteins (7). Moreover, it is believed that the death of neurons and oligodendrocytes in remote areas from the lesion epicenter can be mediated through cytokines such as TNF-, free radical damage and excitotoxicity since calcium from damaged cells within the lesion barely reaches these remote areas (8, 168). Fas mediated cell death has been suggested as a key mechanism of apoptosis following SCI (144, 169172). Post-mortem studies on acute and chronic human SCI and animal models revealed that Fas mediated apoptosis plays a role in oligodendrocyte apoptosis and inflammatory response at acute and subacute stages of SCI (173). Fas deficient mice exhibit a significant reduction in apoptosis and inflammatory response evidenced by reduced macrophage infiltration and inflammatory cytokine expression following SCI (173). Interestingly, Fas deficient mice show a significantly improved functional recovery after SCI (173) suggesting the promise of anti-apoptotic strategies for SCI.

SCI also results in a dysregulated autophagy (174). Normally, autophagy plays an important role in maintaining the homeostasis of cells by aiding in the turnover of proteins and organelles. In autophagy, cells degrade harmful, defective or unnecessary cytoplasmic proteins and organelles through a lysosomal dependent mechanism (175, 176). The process of autophagy starts with the formation of an autophagosome around the proteins and organelles that are tagged for autophagy (176). Next, fusion of the phagosome with a lysosome form an autolysosome that begins a recycling process (176). In response to cell injury and endoplasmic reticulum (ER) stress, autophagy is activated and limits cellular loss (177, 178). Current evidence suggests a neuroprotective role for autophagy after SCI (175, 179). Dysregulation of autophagy contributes to neuronal loss (174, 180). Accumulation of autophagosomes in ventral horn motor neurons have been detected acutely following SCI (181). Neurons with dysregulated autophagy exhibit higher expression of caspase 12 and become more prone to apoptosis (174). Moreover, blocking autophagy has been associated with neurodegenerative diseases such as Parkinson's and Alzheimer's disease (182184). Autophagy promotes cell survival through elimination of toxic proteins and damaged mitochondria (185, 186). Interestingly, autophagy is crucial in cytoskeletal remodeling and stabilizes neuronal microtubules by degrading SCG10, a protein involved in microtubule disassembly (179). Pharmacological induction of autophagy in a hemi-section model of SCI in mice has been associated with improved neurite outgrowth and axon regeneration, following SCI (179). Altogether, although further studies are needed, autophagy is currently viewed as a beneficial mechanism in SCI.

Neuroinflammation is a key component of the secondary injury mechanisms with local and systemic consequences. Inflammation was originally thought to be detrimental for the outcome of SCI (187). However, now it is well-recognized that inflammation can be both beneficial and detrimental following SCI, depending on the time point and activation state of immune cells (188). There are multiple cell types involved in the inflammatory response following injury including neutrophils, resident microglia, and astrocytes, dendritic cells (DCs), blood-born macrophages, B- and T-lymphocytes (189) (). The first phase of inflammation (02 days post injury) involves the recruitment of resident microglia and astrocytes and blood-born neutrophils to the injury site (190). The second phase of inflammation begins approximately 3 days post injury and involves the recruitment of blood-born macrophages, B- and T-lymphocytes to the injury site (189, 191193). T lymphocytes become activated in response to antigen presentation by macrophages, microglia and other antigen presenting cells (APCs) (194). CD4+ helper T cells produce cytokines that stimulate B cell antibody production and activate phagocytes (195) (). In SCI, B cells produce autoantibodies against injured spinal cord tissue, which exacerbate neuroinflammation and cause tissue destruction (196). While inflammation is more pronounced in the acute phase of injury, it continues in subacute and chronic phase and may persist for the remainder of a patients' life (193). Interestingly, composition and phenotype of inflammatory cells change based on the injury phase and the signals present in the injury microenvironment. It is established that microglia/macrophages, T cells, B cells are capable of adopting a pro-inflammatory or an anti-inflammatory pro-regenerative phenotype in the injured spinal cord (191, 197199). The role of each immune cell population in the pathophysiology of SCI will be discussed in detail in upcoming sections.

Immune response in spinal cord injury. Under normal circumstances, there is a balance between pro-inflammatory effects of CD4+ effector T cells (Teff) and anti-inflammatory effects of regulatory T and B cells (Treg and Breg). Treg and Breg suppress the activation of antigen specific CD4+ Teff cells through production of IL-10 and TGF-. Injury disrupts this balance and promote a pro-inflammatory environment. Activated microglia/macrophages release pro-inflammatory cytokines and chemokines and present antigens to CD4+ T cells causing activation of antigen specific effector T cells. Teff cells stimulate antigen specific B cells to undergo clonal expansion and produce autoantibodies against spinal cord tissue antigens. These autoantibodies cause neurodegeneration through FcR mediated phagocytosis or complement mediated cytotoxicity. M1 macrophages/microglia release pro-inflammatory cytokines and reactive oxygen species (ROS) that are detrimental to neurons and oligodendrocytes. Breg cells possess the ability to promote Treg development and restrict Teff cell differentiation. Breg cells could also induce apoptosis in Teff cells through Fas mediate mechanisms.

Astrocytes are not considered an immune cell per se; however, they play pivotal roles in the neuroinflammatory processes in CNS injury and disease. Their histo-anatomical localization in the CNS has placed them in a strategic position for participating in physiological and pathophysiological processes in the CNS (200). In normal CNS, astrocytes play major roles in maintaining CNS homeostasis. They contribute to the structure and function of blood-brain-barrier (BBB), provide nutrients and growth factors to neurons (200), and remove excess fluid, ions, and neurotransmitters such as glutamate from synaptic spaces and extracellular microenvironment (200). Astrocytes also play key roles in the pathologic CNS by regulating BBB permeability and reconstruction as well as immune cell activity and trafficking (201). Astrocytes contribute to both innate and adaptive immune responses following SCI by differential activation of their intracellular signaling pathways in response to environmental signals (201).

Astrocytes react acutely to CNS injury by increasing cytokine and chemokine production (202). They mediate chemokine production and recruitment of neutrophils through an IL-1R1-Myd88 pathway (202). Activation of the nuclear factor kappa b (NF-B) pathway, one of the key downstream targets of interleukin (IL)1R-Myd88 axis, increases expression of intracellular adhesion molecule (ICAM) and vascular cell adhesion molecule (VCAM), which are necessary for adhesion and extravasation of leukocytes in inflammatory conditions such as SCI (201, 202). Within minutes of injury, production of IL-1 is significantly elevated in astrocytes and microglia (203). Moreover, chemokines such as monocyte chemoattractant protein (MCP)-1, chemokine C-C motif ligand 2 (CCL2), C-X-C motif ligand 1 (CXCL1), and CXCL2 are produced by astrocytes, and enhance the recruitment of neutrophils and pro-inflammatory macrophages following injury (201, 202). Astrocytes also promote pro-inflammatory M1-like phenotype in microglia/macrophages in the injured spinal cord through their production of TNF-, IL-12, and IFN- (204206). Interestingly, astrocytes also produce anti-inflammatory cytokines, such as TGF- and IL-10, which can promote a pro-regenerative M2-like phenotype in microglia/macrophages (201, 207, 208).

Immunomodulatory role of astrocytes is defined by activity of various signaling pathways through a wide variety of surface receptors (200). For example, gp130, a member of IL-6 cytokine family, activates SHP2/Ras/Erk signaling cascade in astrocytes and limits neuroinflammation in autoimmune rodent models (209). TGF- signaling in astrocytes has been implicated in modulation of neuroinflammation through inhibition of NF-B activity and nuclear translocation (201, 210). STAT3 is another key signaling pathway in astrocytes with beneficial properties in neuroinflammation. Increase in STAT3 phosphorylation enhances astrocytic scar formation and restricts the expansion of inflammatory cells in mouse SCI, which is associated with improved functional recovery (211). Detrimental signaling pathways in astrocytes are known to be activated by cytokines, sphingolipids and neurotrophins (200). As an example, IL-17 is a key pro-inflammatory cytokine produced by effector T cells that can bind to IL-17R on the astrocyte surface (200). Activation of IL-17R results in the activation of NF-B, which enhances expression of pro-inflammatory mediators, activation of oxidative pathways and exacerbation of neuroinflammation (200, 212). This evidence shows the significance of astrocytes in the inflammatory processes following SCI and other neuroinflammatory diseases of the CNS.

Neutrophils infiltrate the spinal cord from the bloodstream within the first few hours after injury (213). Their population increases acutely in the injured spinal cord tissue and reaches a peak within 24 h post-injury (214). The presence of neutrophils is mostly limited to the acute phase of SCI as they are rarely found sub-acutely in the injured spinal cord (214). The role of neutrophils in SCI pathophysiology is controversial. Evidence shows that neutrophils contribute to phagocytosis and clearance of tissue debris (48). They release inflammatory cytokines, proteases and free radicals that degrade ECM, activate astrocytes and microglia and initiate neuroinflammation (48). Although neutrophils have been conventionally associated with tissue damage (48, 215), their elimination compromises the healing process and impedes functional recovery (216).

To elucidate the role of neutrophils in SCI, Stirling and colleagues used a specific antibody to reduce circulating LyG6/Gr1+ neutrophils in a mouse model of thoracic contusive SCI (216). This approach significantly reduced neutrophil infiltration in the injured spinal cord by 90% at 24 and 48 h after SCI (216). Surprisingly, neutrophil depletion aggravated the neurological and structural outcomes in the injured animals suggesting a beneficial role for neutrophils in the acute phase of injury (216). It is shown that simulated neutrophils release IL-1 receptor antagonist that can exert neuroprotective effects following SCI (217). Moreover, ablation of neutrophils results in altered expression of cytokines and chemokines and downregulation of growth factors such as fibroblast growth factors (FGFs), vascular endothelial growth factors (VEGFs) and bone morphogenetic proteins (BMPs) in the injured spinal cord that seemingly disrupt the normal healing process (216). Altogether, neutrophils play important roles in regulating neuroinflammation at the early stage of SCI that shapes the immune response and repair processes at later stages. While neutrophils were originally viewed as being detrimental in SCI, emerging evidence shows their critical role in the repair process. Further investigations are required to elucidate the role of neutrophils in SCI pathophysiology.

Following neutrophil invasion, microglia/macrophages populate the injured spinal cord within 23 days post-SCI. Macrophage population is derived from invading blood-borne monocytes or originate from the CNS resident macrophages that reside in the perivascular regions within meninges and subarachnoid space (218, 219). The population of microglia/macrophages reaches its peak at 710 days post-injury in mouse SCI, followed by a decline in the subacute and chronic phases (20, 220). While macrophages and microglia share many functions and immunological markers, they have different origins. Microglia are resident immune cells of the CNS that originate from yolk sac during the embryonic period (221). Macrophages are derived from blood monocytes, which originate from myeloid progeny in the bone marrow (222, 223). Upon injury, acute disruption of brain-spinal cord barrier (BSB) enables monocytes, to infiltrate the spinal cord tissue and transform into macrophages (222). Macrophages populate the injury epicenter, while resident microglia are mainly located in the perilesional area (222). Once activated, macrophages, and microglia are morphologically and immunohistologically indistinguishable (224). Macrophages and microglia play a beneficial role in CNS regeneration. They promote the repair process by expression of growth promoting factors such as nerve growth factor (NGF), neurotrophin-3 (NT-3) and thrombospondin (225, 226). Macrophages and microglia are important for wound healing process following SCI due to their ability for phagocytosis and scavenging damaged cells and myelin debris following SCI (222, 227).

Based on microenvironmental signals, macrophages/microglia can be polarized to either pro-inflammatory (M1-like) or anti-inflammatory pro-regenerative (M2-like) phenotype, and accordingly contribute to injury or repair processes following SCI (191, 224, 228230). Whether both microglia and macrophages possess the ability to polarize or it is mainly the property of monocyte derived macrophages is still a matter of debate and needs further elucidation (231233). Some evidence show that Proinflammatory M1-like microglia/macrophages can be induced by exposure to Th1 specific cytokine, interferon (IFN)- (224, 230). Moreover, the SCI microenvironment appears to drive M1 polarization of activated macrophages (231). SCI studies have revealed that increased level of the proinflammatory cytokine, TNF-, and intracellular accumulation of iron drives an M1-like proinflammatory phenotype in macrophages after injury (231). Importantly, following SCI, activated M1-like microglia/macrophages highly express MHCII and present antigens to T cells and contribute to the activation and regulation of innate and adaptive immune response () (224, 228). Studies on acute and subacute SCI and experimental autoimmune encephalomyelitis (EAE) models have shown that M1-like macrophages are associated with higher expression of chondroitin sulfate proteoglycans (CSPGs) and increased EAE severity and tissue damage (234237). In vitro, addition of activated M1-like macrophages to dorsal root ganglion (DRG) neuron cultures leads to axonal retraction and failure of regeneration as the expression of CSPGs is much higher in M1-like compared to M2-like macrophages (237, 238). M1-like macrophages also produce other repulsive factors such as repulsive guidance molecule A (RGMA) that is shown to induce axonal retraction following SCI (239, 240). Interestingly, recent evidence shows that IFN- and TNF polarized M1 microglia show reduced capacity for phagocytosis (241), a process that is critical for tissue repair after SCI.

Pro-regenerative M2-like microglia/macrophages, are polarized by Th2 cytokines, IL-4 and IL-13 and exhibit a high level of IL-10, TGF-, and arginase-1 with reduced NF-B pathway activity (224). IL-10 is a potent immunoregulatory cytokine with positive roles in repair and regeneration following CNS injury (242244). IL-10 knock-out mice show higher production of pro-inflammatory and oxidative stress mediators after SCI (245). Lack of IL-10 is also correlated with upregulated levels of pro-apoptotic factors such as Bax and reduced expression of anti-apoptotic factors such as Bcl-2 (245). SCI mice that lacked IL-10 exhibited poorer recovery of function compared to wild-type mice (245). Our recent studies show that IL-10 polarized M2 microglia show enhanced capacity for phagocytosis (241). We have also found that M2 polarized microglia enhance the ability of neural precursor cells for oligodendrocyte differentiation through IL-10 mediated mechanisms (241). In addition to immune modulation, M2-like microglia/macrophages promote axonal regeneration (224). However, similar to the detrimental effects of prolonged M1 macrophage response, excessive M2-like activity promotes fibrotic scar formation through the release of factors such as TGF-, PDGF, VEGF, IGF-1, and Galectin-3 (224, 246248). Hence, a balance between proinflammatory M1 and pro-regenerative M2 macrophage/microglia response is beneficial for the repair of SCI (249).

T and B lymphocytes play pivotal role in the adaptive immune response after SCI (194). Lymphocytes infiltrate the injured spinal cord acutely during the first week of injury and remain chronically in mouse and rat SCI (47, 193, 194, 196). In contrast to the innate immune response that can be activated directly by foreign antigens, the adaptive immune response requires a complex signaling process in T cells elicited by antigen presenting cells (250). Similar to other immune cells, T and B lymphocytes adopt different phenotypes and contribute to both injury and repair processes in response to microenvironmental signals (194, 251). SCI elicits a CNS-specific autoimmune response in T and B cells, which remains active chronically (196). Autoreactive T cells can exert direct toxic effects on neurons and glial cells (194, 252). Moreover, T cells can indirectly affect neural cell function and survival through pro-inflammatory cytokine and chemokine production (e.g. IL-1, TNF-, IL-12, CCL2, CCL5, and CXCL10) (194, 252). Genetic elimination of T cells (in athymic nude rats) or pharmacological inhibition of T cells (using cyclosporine A and tacrolimus) leads to improved tissue preservation and functional recovery after SCI (194, 253) signifying the impact of T cells in SCI pathophysiology and repair.

Under normal circumstances, systemic autoreactive effector CD4+ helper T cells (Teff) are suppressed by CD4+FoxP3+ regulatory T cells (Treg) () (194, 254). This inhibition is regulated through various mechanisms such as release of anti-inflammatory cytokines IL-10 and TGF- by the Treg cells () (194). Moreover, it is known that Treg mediated inhibition of antigen presentation by dendritic cells (DCs) prevent Teff cell activation (194). Following SCI, this Treg -Teff regulation is disrupted. Increased activity of autoreactive Teff cells contributes to tissue damage through production of pro-inflammatory cytokines and chemokines, promoting M1-like macrophage phenotype and induction of Fas mediated neuronal and oligodendroglial apoptosis () (173). Moreover, autoreactive Teff cells promote activation and differentiation of antigen specific B cells to autoantibody producing plasma cells that contribute to tissue damage after SCI (255). In SCI and MS patients, myelin specific proteins such as myelin basic protein (MBP) significantly increase the population of circulating T cells (256, 257). Moreover, serological assessment of SCI patients has shown high levels of CNS reactive IgM and IgG isotypes confirming SCI-induced autoimmune activity of T and B cells () (196, 258, 259). In animal models of SCI, serum IgM level increases acutely followed by an elevation in the levels of IgG1 and IgG2a at later time-points (196). In addition to autoantibody production, autoreactive B cells contribute to CNS injury through pro-inflammatory cytokines that stimulate and maintain the activation states of Teff cells (194, 260). B cell knockout mice (BCKO) that have no mature B cell but with normal T cells, show a reduction in lesion volume, lower antibody levels in the cerebrospinal fluid and improved recovery of function following SCI compared to wild-type counterparts (255). Of note, antibody mediated injury is regulated through complement activation as well as macrophages/microglia that express immunoglobulin receptors (193, 255).

The effect of SCI on systemic B cell response is controversial. Evidence shows that SCI can suppress B cell activation and antibody production (261). Studies in murine SCI have shown that B cell function seems to be influenced by the level of injury (262). While injury to upper thoracic spinal cord (T3) suppresses the antibody production, a mid-thoracic (T9) injury has no effect on B cell antibody production (262). An increase in the level of corticosterone in serum together with elevation of splenic norepinephrine found to be responsible for the suppression of B cell function acutely following SCI (261). Elevated corticosterone and norepinephrine leads to upregulation of lymphocyte beta-2 adrenergic receptors eliciting lymphocyte apoptosis (194). This suggests a critical role for sympathetic innervation of peripheral lymphoid tissues in regulating B cell response following CNS injury (261). Despite their negative roles, B cells also contribute to spinal cord repair following injury through their immunomodulatory Breg phenotype () (263). Breg cells control antigen-specific T cell autoimmune response through IL-10 production (264).

Detrimental effects of SCI-induced autoimmunity are not limited to the spinal cord. Autoreactive immune cells contribute to the exacerbation of post-SCI sequelae such as cardiovascular, renal and reproductive dysfunctions (194). For example, presence of an autoantibody against platelet prostacyclin receptor has been associated with a higher incidence of coronary artery disease in SCI patients (265). Collectively, evidence shows the critical role of adaptive immune system in SCI pathophysiology and repair. Thus, treatments that harness the pro-regenerative properties of the adaptive immune system can be utilized to reduce immune mediated tissue damage, improve neural tissue preservation and facilitate repair following SCI.

Traumatic SCI triggers the formation of a glial scar tissue around the injury epicenter (266, 267). The glial scar is a multifactorial phenomenon that is contributed f several populations in the injured spinal cord including activated astrocytes, NG2+ oligodendrocyte precursor cells (OPCs), microglia, fibroblasts, and pericytes (268271). The heterogeneous scar forming cells and associated ECM provides a cellular and biochemical zone within and around the lesion () (272). Resident and infiltrating inflammatory cells contribute to the process of glial activation and scar formation by producing cytokines (e.g., IL-1 and IL-6) chemokines and enzymes that activate glial cells or disrupt BSB (267). Activated microglia/macrophages produce proteolytic enzymes such as matrix metalloproteinases (MMPs) that increase vascular permeability and further disruption of the BSB (273). Inhibition of MMPs improves neural preservation and functional recovery in animal models of SCI (273275). In addition to glial and immune cells, fibroblasts, pericytes and ependymal cells also contribute to the structure of the glial scar (267). In penetrating injuries where meninges are compromised, meningeal fibroblasts infiltrate the lesion epicenter (276). Fibroblasts contribute to the production of fibronectin, collagen, and laminin in the ECM of the inured spinal cord (267) and are a source of axon-repulsing molecules such as semaphorins that influence axonal regeneration following SCI (277). Fibroblasts have also been found in contusive injuries where meninges are intact (268, 270). Studies using genetic fate mapping in these injuries have unraveled that perivascular pericytes and fibroblasts migrate to the injury site and form a fibrotic core in the scar which matures within 2 weeks post-injury (268, 270). SCI also triggers proliferation and migration of the stem/progenitor cell pool of the spinal cord parenchyma and ependyma. These cells can give rise to new scar forming astrocytes and OPCs (278280). In a mature glial scar, activated microglia/macrophages occupy the innermost portion closer to the injury epicenter surrounded by NG2+ OPCs () (267), while reactive astrocytes reside in the injury penumbra and form a cellular barrier (267). Of note, in human SCI, the glial scar begins to form within the first hours after the SCI and remains chronically in the spinal cord tissue (281). The glial scar has been found within the injured human spinal cord up to 42 years after the injury (267).

Activated astrocytes play a leading role in the formation of the glial scar (267). Following injury, astrocytes increase their expression of intermediate filaments, GFAP, nestin and vimentin, and become hypertrophied (282, 283). Reactive astrocytes proliferate and mobilize to the site of injury and form a mesh like structure of intermingled filamentous processes around the injury epicenter (284, 285). The astrocytic glial scar has been shown to serve as a protective barrier that prevents the spread of infiltrating immune cells into the adjacent segments (267, 284, 286). Attenuating astrocyte reactivity and scar formation by blockade of STAT3 activation results in poorer outcomes in SCI (211, 286). Reactive astrogliosis is also essential for reconstruction of the BBB, and blocking this process leads to exacerbated leukocyte infiltration, cell death, myelin damage, and reduced functional recovery (211, 285, 286). Despite the protective role of the astrocytic glial scar in acute SCI, its evolution and persistence in the sub-acute and chronic stages of injury has been considered as a potent inhibitor for spinal cord repair and regeneration (267, 287). A number of inhibitory molecules have been associated with activated astrocytes and their secreted products such as proteoglycans and Tenascin-C (288). Thus, manipulation of the astrocytic scar has been pursued as a promising treatment strategy for SCI (267, 289).

Chondroitin sulfate proteoglycans (CSPGs) are well-known for their contribution to the inhibitory role of the glial scar in axonal regeneration (290295), sprouting (296299), conduction (300302), and remyelination (241, 303307). In normal condition, basal levels of CSPGs are expressed in the CNS that play critical roles in neuronal guidance and synapse stabilization (90, 308). Following injury, CSPGs (neurocan, versican, brevican, and phosphacan) are robustly upregulated and reach their peak of expression at 2 weeks post-SCI and remain upregulated chronically (309, 310). Mechanistically, disruption of BSB and hemorrhage following traumatic SCI triggers upregulation of CSPGs in the glial scar by exposing the scar forming cells to factors in plasma such as fibrinogen (311). Studies in cortical injury have shown that fibrinogen induces CSPG expression in astrocytes through TGF/Smad2 signaling pathway (311). The authors show that intracellular Smad2 translocation is essential for Smad2 signal transduction process and its inhibition reduces scar formation (312). In contrast, another study has identified that TGF induces CSPGs production in astrocytes through a SMAD independent pathway (313). This study showed a significant upregulation of CSPGs in SMAD2 and SMAD4 knockdown astrocytes. Interestingly, CSPG upregulation was found to be mediated by the activation of the phosphoinositide 3-kinase (PI3K)/Akt and mTOR axis (313). Further studies are required to confirm these findings.

Extensive research in the past few decades has demonstrated the inhibitory effect of CSPGs on axon regeneration (314, 315). The first successful attempt on improving axon outgrowth and/or sprouting by enzymatic degradation of CSPGs using chondroitinase ABC (ChABC) in a rat SCI model was published in 2002 by Bradbury and colleagues (291). This study showed significant improvement in recovery of locomotor and proprioceptive functions following intrathecal delivery of ChABC in a rat model of dorsal column injury (291). This observation was followed by several other studies demonstrating the promise of CSPGs degradation in improvement of axon regeneration and sprouting of the serotonergic (295, 297, 299, 303), sensory (293, 298, 316), corticospinal (291, 297, 303, 317), and rubrospinal fibers (318) in animal models of CNS injury. Additionally, ChABC treatment is shown to be neuroprotective by preventing CSPG induced axonal dieback and degeneration (303, 319, 320). Studies by our group also showed that degradation of CSPGs using ChABC attenuates axonal dieback in corticospinal fibers in chronic SCI model in the rat (303). ChABC also blocks macrophage-mediated axonal degeneration in neural cultures and after SCI (238).

The inhibitory effects of astrocytic glial scar on axonal regeneration has been recently challenged after SCI (321). Using various transgenic mouse models, a study by Sofroniew's and colleagues has shown that spontaneous axon regrowth failed to happen following the ablation or prevention of astrocytic scar in acute and chronic SCI. They demonstrated that when the intrinsic ability of dorsal root ganglion (DRG) neurons for growth was enhanced by pre-conditioning injury as well as local delivery of a combination of axon growth promoting factors into the SCI lesion, the axons grew to the wall of the glial scar and CSPGs within the lesion. However, when astrocyte scarring was attenuated, the pre-conditioned/growth factor stimulated DRG neurons showed a reduced ability for axon growth (321). From these observations, the authors suggested a positive role for the astrocytic scar in axonal regeneration following SCI (321). Overall, this study points to the importance of reactive and scar forming astrocytes and their pivotal role in the repair process following SCI (322). This is indeed in agreement with previous studies by the same group that showed a beneficial role for activated astrocytes in functional recovery after SCI by limiting the speared of infiltrated inflammatory cells and tissue damage in SCI (285). It is also noteworthy that the glial scar is contributed by various cell populations and not exclusively by astrocytes (269, 271). Therefore, the outcomes of this study need to be interpreted in the context of astrocytes and astrocytic scar. Moreover, the reduced capacity of the injured spinal cord for regeneration is not solely driven by the glial scar as other factors including inflammation and damaged myelin play important inhibitory role in axon regeneration (323, 324). Taken together, further investigation is needed to delineate the mechanisms of the glial scar including the contribution of astrocyte-derived factors on axon regeneration in SCI.

While CSPGs were originally identified as an inhibitor of axon growth and plasticity within the glial scar, emerging evidence has also identified them as an important regulator of endogenous cell response. Emerging evidence has identified CSPGs as an inhibitor of oligodendrocytes (241, 272, 306). Replacement of oligodendrocytes is an important repair process in SCI and other demyelinating conditions such as MS (90). SCI and MS triggers activation of endogenous OPCs and their mobilization to the site of injury (143, 162, 306, 325). In vitro and in vivo evidence shows that CSPGs limit the recruitment of NPCs and OPCs to the lesion and inhibit oligodendrocyte survival, differentiation and maturation (145, 272, 305, 306, 326). Our group and others have shown that targeting CSPGs by ChABC administration or xyloside, or through inhibition of their signaling receptors enhances the capacity of NPCs and OPCs for proliferation, oligodendrocyte differentiation and remyelination following SCI and MS-like lesions (145, 303, 304, 306).

Mechanistically, the inhibitory effects of CSPGs on axon growth and endogenous cell differentiation is mainly governed by signaling through receptor protein tyrosine phosphatase sigma (RPTP) and leukocyte common antigen-related phosphatase receptor (LAR) (327). RPTP is the main receptor mediating the inhibition of axon growth by CSPGs (327, 328). Improved neuronal regeneration has been demonstrated in RPTP/ mice model of SCI and peripheral nerve injury (328, 329). Blockade of RPTP and LAR by intracellular sigma peptide (ISP) and intracellular LAR peptide (ILP), facilitates axon regeneration following SCI (327, 330). Inhibition of RPTP results in significant improvement in locomotion and bladder function associated with serotonergic re-innervation below the level of injury in rat SCI (327). Our group has also shown that CSPGs induce caspase-3 mediated apoptosis in NPCs and OPCs in vitro and in oligodendrocytes in the injured spinal cord that is mediated by both RPTP and LAR (241). Inhibition of LAR and RPTP sufficiently attenuates CSPG-mediated inhibition of oligodendrocyte maturation and myelination in vitro and attenuated oligodendrocyte cell death after SCI (241).

CSPGs have been implicated in regulating immune response in CNS injury and disease. Interestingly, our recent studies indicated that CSPGs signaling appears to restrict endogenous repair by promoting a pro-inflammatory immune response in SCI (241, 331). Inhibition of LAR and RPTP enhanced an anti-inflammatory environment after SCI by promoting the populations of pro-regenerative M2-like microglia/macrophages and regulatory T cells (241) that are known to promote repair process (224). These findings are also in agreement with recent studies in animal models of MS that unraveled a pro-inflammatory role for CSPGs in autoimmune demyelinating conditions (332). In MS and EAE, studies by Stephenson and colleagues have shown that CSPGs are abundant within the leucocyte-containing perivascular cuff, the entry point of inflammatory cells to the CNS tissue (332). Presence of CSPGs in these perivascular cuffs promotes trafficking of immune cells to induce a pro-inflammatory response in MS condition. In contrast to these new findings, early studies in SCI described that preventing CSPG formation with xyloside treatment at the time of injury results in poor functional outcome, while manipulation of CSPGs at 2 days after SCI was beneficial for functional recovery (333). These differential outcomes were associated with the modulatory role of CSPGs in regulating the response of macrophages/microglia. Disruption in CSPG formation immediately after injury promoted an M1 pro-inflammatory phenotype in macrophages/microglia, whereas delayed manipulation of CSPGs resulted in a pro-regenerative M2 phenotype (333). In EAE, by products of CSPG degradation also improve the outcomes by attenuating T cell infiltration and their expression of pro-inflammatory cytokines IFN- and TNF (334).

These emerging findings suggest an important immunomodulatory role for CSPGs in CNS injury and disease; further investigations are needed to elucidate CSPG mechanisms in regulating neuroinflammation. Altogether, current evidence has identified a multifaceted inhibitory role for CSPGs in regulating endogenous repair mechanisms after SCI, suggesting that targeting CSPGs may present a promising treatment strategy for SCI.

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Traumatic Spinal Cord Injury: An Overview of ...

Spinal Cord Stem Cells Comments Off on Traumatic Spinal Cord Injury: An Overview of … | October 16th, 2021

Abstract

Stem cells or mother or queen of all cells are pleuropotent and have the remarkable potential to develop into many different cell types in the body. Serving as a sort of repair system for the body, they can theoretically divide without limit to replenish other cells as long as the person or animal is alive. When a stem cell divides, each new cell has the potential to either remain a stem cell or become another type of cell with a more specialized function, such as a muscle cell, a red blood cell, or a brain cell. Stem cells differ from other kinds of cells in the body. All stem cells regardless of their source have three general properties:

They are unspecialized; one of the fundamental properties of a stem cell is that it does not have any tissue-specific structures that allow it to perform specialized functions.

They can give rise to specialized cell types. These unspecialized stem cells can give rise to specialized cells, including heart muscle cells, blood cells, or nerve cells.

They are capable of dividing and renewing themselves for long periods. Unlike muscle cells, blood cells, or nerve cells which do not normally replicate themselves - stem cells may replicate many times. A starting population of stem cells that proliferates for many months in the laboratory can yield millions of cells. Today, donated organs and tissues are often used to replace those that are diseased or destroyed. Unfortunately, the number of people needing a transplant far exceeds the number of organs available for transplantation. Pleuropotent stem cells offer the possibility of a renewable source of replacement cells and tissues to treat a myriad of diseases, conditions, and disabilities including Parkinsons and Alzheimers diseases, spinal cord injury, stroke, Cerebral palsy, Battens disease, Amyotrophic lateral sclerosis, restoration of vision and other neuro degenerative diseases as well.

Stem cells may be the persons own cells (a procedure called autologous transplantation) or those of a donor (a procedure called allogenic transplantation). When the persons own stem cells are used, they are collected before chemotherapy or radiation therapy because these treatments can damage stem cells. They are injected back into the body after the treatment.

The sources of stem cells are varied such as pre-implantation embryos, children, adults, aborted fetuses, embryos, umbilical cord, menstrual blood, amniotic fluid and placenta

New research shows that transplanted stem cells migrate to the damaged areas and assume the function of neurons, holding out the promise of therapies for Alzheimers disease, Parkinsons, spinal cord injury, stroke, Cerebral palsy, Battens disease and other neurodegenerative diseases.

The therapeutic use of stem cells, already promising radical new treatments for cancer, immune-related diseases, and other medical conditions, may someday be extended to repairing and replenishing the brain. In a study published in the February 19, 2002, Proceedings of the National Academy of Sciences, researchers exposed the spinal cord of a rat to injury, paralyzing the animals hind limbs and lower body. Stem cells grown in exponential numbers in the laboratory were then injected into the site of the injury. It was seen that week after the injury, motor function improved dramatically,

The following diseases have been treated by various stem cell practitioners with generally positive results and the spectrum has ever since been increasing.

Cerebral palsy is a disorder caused by damage to the brain during pregnancy, delivery or shortly after birth. It is often accompanied by seizures, hearing loss, difficulty speaking, blindness, lack of co-ordination and/or mental retardation. Studies in animals with experimentally induced strokes or traumatic injuries have indicated that benefit is possible by stem cell therapy. The potential to do these transplants via injection into the vasculature rather than directly into the brain increases the likelihood of timely human studies. As a result, variables appropriate to human experiments with intravascular injection of cells, such as cell type, timing of the transplant and effect on function, need to be systematically performed in animal models Studies in animals with experimentally induced strokes or traumatic injuries have indicated that benefit is possible with injury, with the hope of rapidly translating these experiments to human trials.(1)

Cerebral palsy produces chronic motor disability in children. The causes are quite varied and range from abnormalities of brain development to birth-related injuries to postnatal brain injuries. Due to the increased survival of very premature infants, the incidence of cerebral palsy may be increasing. While premature infants and term infants who have suffered neonatal hypoxic-ischemic (HI) injury represent only a minority of the total cerebral palsy population, this group demonstrates easily identifiable clinical findings, and much of their injury is to oligodendrocytes and the white matter (2)

Alzheimers is a complex, fatal disease involving progressive cell degeneration, beginning with the loss of brain cells that control thought, memory and language. The disease, which currently has no cure, was first described by German physician Dr. Alzheimer, who discovered amyloid plaques and neurofibrillary tangles in the brain of a woman who died of an unusual mental illness. A compound similar to the components of DNA may improve the chances that stem cells transplanted from a patients bone marrow to the brain will take over the functions of damaged cells and help treat Alzheimers disease and other neurological illnesses. A research team led by University of Central Florida professor Kiminobu Sugaya found that treating bone marrow cells in laboratory cultures with bromodeoxyuridine, a compound that becomes part of DNA, made adult human stem cells more likely to develop as brain cells after they were implanted in adult rat brains.

It has long been recognized that Alzheimers disease (AD) patients present an irreversible decline of cognitive functions as consequence of cell deterioration in a structure called nucleus basalis of Meynert The reduction of the number of cholinergic cells causes interference in several aspects of behavioral performance including arousal, attention, learning and emotion. It is also common knowledge that AD is an untreatable degenerative disease with very few temporary and palliative drug therapies. Neural stem cell (NSC) grafts present a potential and innovative strategy for the treatment of many disorders of the central nervous system including AD, with the possibility of providing a more permanent remedy than present drug treatments. After grafting, these cells have the capacity to migrate to lesioned regions of the brain and differentiate into the necessary type of cells that are lacking in the diseased brain, supplying it with the cell population needed to promote recovery. (3)

Malignant multiple sclerosis (MS) is a rare but clinically important subtype of MS characterized by the rapid development of significant disability in the early stages of the disease process. These patients are refractory to conventional immunomodulatory agents and the mainstay of their treatment is plasmapheresis or immunosuppression with mitoxantrone, cyclophosphamide, cladribine or, lately, bone marrow transplantation. A report on the case of a 17-year old patient with malignant MS who was treated with high-dose chemotherapy plus anti-thymocyte globulin followed by autologous stem cell transplantation. This intervention resulted in an impressive and long-lasting clinical and radiological response (4).

In other experiment treatment of 24 patients (14 women, 10 men) with relapsing-remitting Multiple Sclerosis, in the course of 28 years was done For treatment, used were embryonic stem cell suspensions (ESCS) containing stem cells of mesenchymal and ectodermal origin obtained from active growth zones of 48 weeks old embryonic cadavers organs. Suspensions were administered in the amount of 13 ml, cell count being 0,1-100x105/ml. In the course of treatment, applied were 24 different suspensions, mode of administration being intracavitary, intravenous, and subcutaneous. After treatment, syndrome of early post-transplant improvement was observed in 70% of patients, its main manifestations being decreased weakness, improved appetite and mood, decreased depression. In the course of first post-treatment months, positive dynamics was observed in the following aspects: Nystagmus, convergence disturbances, spasticity, and coordination. In such symptoms as dysarthria, dysphagia, and ataxia, positive changes occurred at much slower rate. In general, the treatment resulted in improved range and quality of motions in the extremities, normalized muscle tone, decreased fatigue and general weakness, and improved quality of life. Forth, 87% of patients reported no exacerbations, no aggravation of neurological symptoms, and no further progression of disability. MRI performed in 12 years after the initial treatment, showed considerable subsidence of focal lesions, mean by 31%, subsidence of gadolinium enhanced lesions by 48%; T2-weighted images showed marked decrease of the focis relative density.

Doctors firstly isolated adult stem cells from the patients brain, they were then cultured in vitro and encouraged to turn into dopamine-producing neurons. As soon as tests showed that the cells were producing dopamine they were then re-injected into the mans brain. After the transplant, the mans condition was seen to improve and he experienced a reduction in the trembling and muscle rigidity associated with the disease. Brain scans taken 3-months after the transplant revealed that dopamine production had increased by 58%, however it later dropped but the Parkinsons symptoms did not return. The study is the first human study to show that stem cell transplants can help to treat Parkinsons.

The use of fetal-derived neural stem cells has shown significant promise in rodent models of Parkinsons disease, and the potential for tumorigenicity appears to be minimal. The authors report that undifferentiated human neural stem cells (hNSCs) transplanted into severely Parkinsonian 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated primates could survive, migrate, and induce behavioral recovery of Parkinsonian symptoms, which were directly related to reduced dopamine levels in the nigrostriatal system(5). Working with these cells, the researchers created dopamine neurons deficient in DJ-1, a gene mutated in an inherited form of Parkinsons. They report that DJ-1-deficient cells -- and especially DJ-1-deficient dopamine neurons -- display heightened sensitivity to oxidative stress, caused by products of oxygen metabolism that react with and damage cellular components like proteins and DNA. In a second paper, they link DJ-1 dysfunction to the aggregation of alpha-synuclein, a hallmark of Parkinsons neuropathology. (6,7)

In summary most of studies using aborted human embryonic tissue indicate that:

Clinical benefit does occur; however, the benefit is not marked and there is a delay of many months before the clinical change.

Postmortem examinations show that tissue grafts do survive and innervate the striatum.

PET scans show that there is an increase in dopamine uptake after transplantation.

Followup studies show that long term benefit does occur with transplantation.(8)

During and after a stroke, certain cellular events take place that lead to the death of brain cells. Compounds that inhibit a group of enzymes called histone deacetylases can modulate gene expression, and in some cases produce cellular proteins that are actually neuroprotective -- they are able to block cell death. Great deal of research has gone into developing histone deacetylase inhibitors as novel therapeutics (9)

One Mesenchymal stem cell (MSC) transplantation improves recovery from ischemic stroke in animals. The Researchers examined the feasibility, efficacy, and safety of cell therapy using culture-expanded autologous MSCs in patients with ischemic stroke. They prospectively and randomly allocated 30 patients with cerebral infarcts within the middle cerebral arterial territory Serial evaluations showed no adverse cell-related, serological, or imaging-defined effects. In patients with severe cerebral infarcts, the intravenous infusion of autologous MSCs appears to be a feasible and safe therapy that may improve functional recovery.(10)

Early intravenous stem cell injection displayed anti-inflammatory functionality that promoted neuroprotection, mainly by interrupting splenic inflammatory responses after intra cranial Haemorrage.

In summary, early intravenous NSC injection displayed anti-inflammatory functionality that neural stem cell (NSC) transplantation has been investigated as a means to reconstitute the damaged brain after stroke. In this study, however, was investigated the effect on acute cerebral and peripheral inflammation after intracerebral haemorrhage (ICH). STEM CELLS from fetal human brain were injected intravenously (NSCs-iv, 5 million cells) or intracerebrally (NSCs-ic, 1 million cells) at 2 or 24 h after collagenase-induced ICH in a rat model. Only NSCs-iv-2 h resulted in fewer initial neurologic deteriorations and reduced brain edema formation, inflammatory infiltrations and apoptosis. (11)

Emerging cell therapies for the restoration of sight have focused on two areas of the eye that are critical for visual function, the cornea and the retina. The relatively easy access of the cornea, the homogeneity of the cells forming the different layers of the corneal epithelium and the improvement of cell culture protocols are leading to considerable success in corneal epithelium restoration. Rebuilding the entire cornea is however still far from reality. The restoration of the retina has recently been achieved in different animal models of retinal degeneration using immature photoreceptors (12)

Bone marrow contains stem cells, which have the extraordinary abilities to home in on injuries and possibly regenerate other cell types in the body. In this case, the cells were transplanted to confirm that bone marrow does regenerate the injured RPE. Damage to RPE is present in many diseases of the retina, including age-related macular degeneration, which affects more than 1.75 million people in the United States. (13)

Neural stem cells (NSCs) offer the potential to replace lost tissue after nervous system injury. Thus, stem cells can promote host neural repair in part by secreting growth factors, and their regeneration-promoting activities can be modified by gene delivery.

Attempted repair of human spinal cord injury by transplantation of stem cells depends on complex biological interactions between the host and graft

Extrapolating results from experimental therapy in animals to humans with spinal cord injury requires great caution.

There is great pressure on surgeons to transplant stem cells into humans with spinal cord injury. However, as the efficacy of and exact indications for this therapy are still uncertain, and morbidity (such as rejection or late tumour development) may result, only carefully designed studies based on sound experimental work which attempts to eliminate placebo effects should proceed.

Premature application of stem cell transplantation in humans with spinal cord injury should be discouraged. 14, 15, 16)

Attempted repair of human spinal cord injury by transplantation of stem cells depends on complex biological interactions between the host and graft

Extrapolating results from experimental therapy in animals to humans with spinal cord injury requires great caution.

There is great pressure on surgeons to transplant stem cells into humans with spinal cord injury. However, as the efficacy of and exact indications for this therapy are still uncertain, and morbidity (such as rejection or late tumour development) may result, only carefully designed studies based on sound experimental work which attempts to eliminate placebo effects should proceed.

Premature application of stem cell transplantation in humans with spinal cord injury should be discouraged.

Mesenchymal stem cells have also been identified and are currently being developed for bone, cartilage, muscle, tendon, and ligament repair and regeneration. These MSCs are typically harvested, isolated, and expanded from bone marrow or adipose tissue, and they have been isolated from rodents, dogs, and humans. Interestingly, these cells can undergo extensive sub cultivation in vitro without differentiation, magnifying their potential clinical use.(17) Human MSCs can be directed toward osteoblastic differentiation by adding dexamethasone, ascorbic acid, and -glycerophosphate to the tissue culture media. This osteoblastic commitment and differentiation can be clearly documented by analyzing alkaline phosphatase activity, the expression of bone matrix proteins, and the mineralization of the extracellular matrix.(18)

Children with Battens disease suffer seizures, motor control disturbances, blindness and communication problems. As many as 600 children in the US are currently diagnosed with the condition.(19)

Death can occur in children as young as 8 years old. The children lack an enzyme for breaking down complex fat and protein compounds in the brain, explains Robert Steiner, vice chair of paediatric research at the hospital. The material accumulates and interferes with tissue function, ultimately causing brain cells to die. Tests on animals demonstrated that stem cells injected into the brain secreted the missing enzyme. And the stem cells were found to survive well in the rodent brain. Once injected, the purified neural cells may develop into neurons or other nervous system tissue, including oligodendrocytes, or glial cells, which support the neurons(20).

In a study that demonstrates the promise of cell-based therapies for diseases that have proved intractable to modern medicine, a team of scientists from the University of Wisconsin-Madison has shown it is possible to rescue the dying neurons characteristic of amyotrophic lateral sclerosis (ALS), a fatal neuromuscular disorder also known as Lou Gehrigs disease. Previously there was no effective treatments for ALS, which afflicts roughly 40,000 people in the United States and which is almost always fatal within three to five years of diagnosis. Patients gradually experience progressive muscle weakness and paralysis as the motor neurons that control muscles are destroyed by the disease

In the new Wisconsin study, nascent brain cells known as neural progenitor cells derived from human fetal tissue were engineered to secrete a chemical known as glial cell line derived neurotrophic factor (GDNF), an agent that has been shown to protect neurons but that is very difficult to deliver to specific regions of the brain. The engineered cells were then implanted in the spinal cords of rats afflicted with a form of ALS. The implanted cells, in fact, demonstrated an affinity for the areas of the spinal cord where motor neurons were dying. The cells after being injected to the area of damage where they just sit and release GDNF. At the early stages of disease, almost 100 percent protection of motor neurons was seen. (21)

In other study MSCs were isolated from bone marrow of 9 patients with definite ALS. Growth kinetics, immunophenotype, telomere length and karyotype were evaluated during in vitro expansion. No significant differences between donors or patients were observed. The patients received intraspinal injections of autologous MSCs at the thoracic level and monitored for 4 years. No significant acute or late side effects were evidenced. No modification of the spinal cord volume or other signs of abnormal cell proliferation were observed. The results seem to demonstrate that MSCs represent a good chance for stem cell cell-based therapy in ALS and that intraspinal injection of MSCs is safe also in the long term. A new phase 1 study is carried out to verify these data in a larger number of patients. (22)

Stem-cell-based technology offers amazing possibilities for the future. These include the ability to reproduce human tissues and potentially repair damaged organs (such as the brain, spinal cord, vertebral column the eye), where, at present, we mainly provide supportive care to prevent the situation from becoming worse. This potential almost silences the sternest critics of such technology, but the fact remains that the ethical challenges are daunting. It is encouraging that, in tackling these challenges, we stand to reflect a great deal about the ethics of our profession and our relationships with patients, industry, and each other. The experimental basis of stem-cell or OEC transplantation should be sound before these techniques are applied to humans with neurological disorders.

1. Stem cell therapy for cerebral palsy. Bartley J, Carroll JE. Department of Pediatrics of the Medical College of Georgia, Augusta, Georgia, USA

8. Department of Neurology, Mt. Sinai School of Medicine, New York, NY, Medscape journal. Stem Cell Transplantation for Parkinsons Disease

9. Journal of Medicinal Chemistry. Future Therapies For Stroke May Block Cell Death 16 Jun 2007

10. Neurosurg Focus. 2005;19(6) 2005 American Association of Neurological Surgeons

11. Brain Advance Access originally published online on December 20, 2007 Brain 2008 Anti-inflammatory mechanism of intravascular neural stem cell transplantation in haemorrhagic stroke.

13. University of Florida(2006, June 8). Bone Marrow May Restore Cells Lost In Vision Diseases. ScienceDaily.

18. Autologous mesenchymal stem cell transplantation in stroke patients Oh Young Bang, MD, PhD 1, Jin Soo Lee, MD Department of Neurology, School of Medicine, Ajou University, Suwon, South Korea Brain Disease Research Center, School of Medicine, Ajou University, Suwon, South Korea.

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Role of Stem Cells in Treatment of Neurological Disorder

Spinal Cord Stem Cells Comments Off on Role of Stem Cells in Treatment of Neurological Disorder | October 16th, 2021

Stem cell research holds great promise for biomedical sciencefrom helping us better understand how diseases develop and spread, to serving as accurate screens for new drugs, to developing cell-based therapies for diabetes, heart failure, Parkinsons disease, and many other conditions that affect millions of Americans. There are 2 basic types of human stem cells: embryonic stem (ES) cells and non-embryonic, or adult stem cells. Just a few years ago, scientists discovered how to make a third type, by reprogramming ordinary skin cells that have already grown up into those that look and act like cells from an embryo. These cells have been named induced pluripotent stem cells, or iPS cells.

NIH research is progressing on multiple fronts to learn more about the differences between the 3 stem cell types and to create patient-specific cells for in-depth study of many diseases. The ability to create iPS cells is a significant breakthrough, since the reprogramming technique is relatively simple to perform with standard laboratory methods, and because skin cells are easy to gather and grow. The most exciting aspect of this research is its potential to speed progress toward achieving personalized therapies. With refinements, this method could yield an unlimited supply of customized cells.

Regenerative medicine is moving toward a day when we can repair and replace damaged tissues. In time, we will be able to make insulin-secreting pancreatic cells, bone cells to heal breaks and defects, and eye and ear cells to restore vision and hearing. NIH researchers are hard at work using stem cells as a powerful tool to study neurological disorders like Parkinsons, Huntingtons disease, amyotrophic lateral sclerosis (ALS), and spinal cord injury, to name a few.

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Stem Cells | National Institutes of Health (NIH)

Spinal Cord Stem Cells Comments Off on Stem Cells | National Institutes of Health (NIH) | October 16th, 2021

Tests to determine how blood pressure changes during certain maneuvers

During the physical examination, doctors can check for signs of autonomic disorders, such as orthostatic hypotension. For example, they measure blood pressure and heart rate while a person is lying down or sitting and after the person stands to check how blood pressure changes when position is changed. When a person stands up, gravity makes it harder for blood from the legs to get back to the heart. Thus, blood pressure decreases. To compensate, the heart pumps harder, and the heart rate increases. However, the changes in heart rate and blood pressure are slight and brief. If the changes are larger or last longer, the person may have orthostatic hypotension.

The tilt table test and the Valsalva maneuver, done together, can help doctors determine whether a decrease in blood pressure is due to an autonomic nervous system disorder.

Doctors examine the pupils for abnormal responses or lack of response to changes in light.

Sweat testing is also done. For one sweat test, the sweat glands are stimulated by electrodes that are filled with acetylcholine and placed on the legs and forearm. Then, the volume of sweat is measured to determine whether sweat production is normal. A slight burning sensation may be felt during the test.

In the thermoregulatory sweat test, a dye is applied to the skin, and a person is placed in a closed, heated compartment to stimulate sweating. Sweat causes the dye to change color. Doctors can then evaluate the pattern of sweat loss, which may help them determine the cause of the autonomic nervous system disorder.

Other tests may be done to check for disorders that can cause the autonomic disorder.

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Overview of the Autonomic Nervous System - Brain, Spinal ...

Spinal Cord Stem Cells Comments Off on Overview of the Autonomic Nervous System – Brain, Spinal … | October 16th, 2021

DUARTE, Calif.--(BUSINESS WIRE)--As a 16-year-old high school sophomore, Julian Castaeda was focused on running track specifically, trying to run a mile in under five minutes. He was also planning to attend two camps that summer that would help him prepare for the rigors of college.

Despite being diagnosed with precursor B cell acute lymphoblastic leukemia at age 10 and receiving chemotherapy on and off for three and a half years, Castaeda had been in remission for two years. He had moved on from that difficult experience.

But in March 2017, Castaeda and his mother, Erica Palacios, again received devastating news the leukemia had returned. Castaeda received chemotherapy for a few months, but the cancer kept proliferating. Castaeda would need a hematopoietic stem cell transplant (more commonly referred to as a bone marrow transplant, or BMT) this time to put his cancer back into remission.

It was heartbreaking. I knew at that point that all my plans for sophomore year would be gone, Castaeda recalled.

But Castaeda was determined to get his life back. This was possible thanks to Johannes Eppler, 27, of Breisach, Germany, who joined the bone marrow registry via DKMS, an international nonprofit that is dedicated to the fight against blood cancers and blood disorders, including the recruitment of bone marrow donors. Castaeda received a bone marrow transplant on Aug. 2, 2017, putting the cancer into remission.

He has a big heart, Palacios said about Eppler. Hes an angel. He saved my son. I am thankful that people are willing to [donate].

Castaeda, who grew up in Bakersfield, California, and was treated by City of Hopes Joseph Rosenthal, M.D., M.H.C.M., the Barron Hilton Chair in Pediatrics, is now 20 years old and a junior at California State University Northridge. He also founded Bags of Love Foundation, a nonprofit that has delivered more than 200 care packages to young cancer patients in treatment and has provided $11,000 in scholarships to survivors.

On Friday, Oct. 15, Castaeda will meet his donor for the first time virtually during City of Hopes BMT Reunion. City of Hope, a pioneer and leader in BMT, has hosted a Celebration of Life for bone marrow, stem cell and cord blood transplant recipients, their families and donors for more than 40 years. The celebration honors children and adult cancer survivors, including those who have received autologous transplants, which use a patients own stem cells, and those who received an allogeneic procedure, which require a bone marrow or stem cell donation from a related or unrelated donor.

What began with a birthday cake and a single candle representing a patients first year free from cancer has grown into an annual extravaganza that draws thousands of cancer survivors, donors and families from around the world, as well as the doctors, nurses and staff who help them through the lifesaving therapy.

Each year, patient-donor meetings are the events emotional highlight. Many recipients, though overwhelmed with curiosity and the need to express their gratitude, can only dream of meeting the stranger who saved their lives. City of Hope is making that dream come true for Castaeda, as well as Dona Garrish, a Fullerton, California resident and retired school teacher. Her donor was Michael Fischer, 35, of Wlkau, Germany.

Garrish, 75, received her transplant on March 22, 2017, after it was delayed several times due to infections and other complications that prevented her from going through with the treatment. Garrish, who was diagnosed with acute myeloid leukemia, felt a strong connection to Fischer from the first time a City of Hope employee told her a German male, whom she had never met, was a perfect match for her. She refers to him as her gift from God and her angel on Earth.

He unknowingly encouraged me to fight harder and not to become discouraged, as someday I wanted to meet him and thank him, she added. Garrish recalled watching two patients meeting their donors at the 2017 BMT Reunion. The reunions were held in front of City of Hope Helford Clinical Research Hospital, where Garrish was recovering from her transplant.

While tethered to her IV pole, Garrish looked down from the hospitals sixth floor and said, Thats what I want to do.

City of Hope nurses, doctors and staff were constantly there supporting me every step of the way, even when I couldnt take a single step, said Garrish, who was treated by City of Hopes Liana Nikolaenko, M.D. The timing was urgent, my battle was rough and long, but I live, breathe and enjoy life today because of City of Hope.

Other event highlights include videos of grateful patients wearing the signature BMT buttons that display the number of years since their transplants, comedy by City of Hope BMT patient Sean Kent and a dance/song performed by BMT nurses, known as the Marrowettes. There will be special guest appearances by a Los Angeles Dodger and Katharina Harf, executive chairwoman of DKMS U.S., to congratulate patients, their donors and the BMT program.

During our annual BMT reunion, we express our most heartfelt thanks to the many selfless individuals who each year donate their bone marrow or stem cells to save a persons life, said Stephen J. Forman, M.D., director of City of Hopes Hematologic Malignancies Research Institute and former chair of its Department of Hematology & Hematopoietic Cell Transplantation. Whether the donor is a patients family member or a person she or he has never met, we are all extremely grateful that these donors took the time to donate and gave someone a second chance at life.

About City of Hopes BMT program

City of Hopes BMT program has performed more than 17,000 transplants, making it one of the largest and most successful programs in the nation. The institution has the largest BMT program in California, performing over 700 transplants annually, and is among the top three hospitals in the nation in terms of total transplants performed.

Over the years, City of Hope has also helped pioneer several BMT innovations. In addition to being one of the first institutions to perform BMTs in older adults, it was one of the first programs to show that BMTs could be safely performed for patients with HIV. City of Hope has had growing success with nonrelated matched donors and, most recently, half matched family donors.

City of Hopes BMT program is the only one in the nation that has had one-year survival above the expected rate for 15 consecutive years, based on analysis by the Center for International Blood and Marrow Transplant Research.

City of Hope was also one of the first programs to develop a treatment for prevention of cytomegalovirus (CMV), a common and potentially deadly infection after transplant, which has nearly eliminated the threat of CMV for BMT patients. The institution successfully conducted clinical trials of a CMV vaccine developed at City of Hope. As a pioneer in the development of CAR T cells to treat cancer, City of Hope is also testing how this form of cancer immunotherapy can help patients have a more successful transplant.

In addition, Be The Match at City of Hope last year added more than 13,000 new volunteers willing to save a life when they match a patient who needs a bone marrow transplant. In total, nearly 300,000 potential donors have signed up via City of Hope, motivated by a patient at the cancer center. Be The Match encourages healthy individuals between the ages of 18 and 40 to take the first step of registering by texting COHSAVES to 61474. To learn more about the donation process, visit Be The Match at City of Hopes website.

The public can register to view the event here.

About City of Hope

City of Hope is an independent biomedical research and treatment center for cancer, diabetes and other life-threatening diseases. Founded in 1913, City of Hope is a leader in bone marrow transplantation and immunotherapy such as CAR T cell therapy. City of Hopes translational research and personalized treatment protocols advance care throughout the world. Human synthetic insulin, monoclonal antibodies and numerous breakthrough cancer drugs are based on technology developed at the institution. A National Cancer Institute-designated comprehensive cancer center and a founding member of the National Comprehensive Cancer Network, City of Hope is ranked among the nations Best Hospitals in cancer by U.S. News & World Report. Its main campus is located near Los Angeles, with additional locations throughout Southern California and in Arizona. Translational Genomics Research Institute (TGen) became a part of City of Hope in 2016. AccessHope, a subsidiary launched in 2019, serves employers and their health care partners by providing access to NCI-designated cancer center expertise. For more information about City of Hope, follow us on Facebook, Twitter, YouTube or Instagram.

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College Student and Retired Teacher to Thank Stem Cell Donors They've Never Met for Saving Their Lives During City of Hope's 45th Bone Marrow...

Bone Marrow Stem Cells Comments Off on College Student and Retired Teacher to Thank Stem Cell Donors They’ve Never Met for Saving Their Lives During City of Hope’s 45th Bone Marrow… | October 16th, 2021

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The post Rheumatoid Arthritis Stem Cell Therapy Market By Type (Allogeneic Mesenchymal Stem Cells, Bone Marrow Transplant, Adipose Tissue Stem Cells) and By Application (Rheumatoid Arthritis Stem Cell Therapy) Forecast to 2021-2031 appeared first on The Swiss Times.

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Rheumatoid Arthritis Stem Cell Therapy Market By Type (Allogeneic Mesenchymal Stem Cells, Bone Marrow Transplant, Adipose Tissue Stem Cells) and By...

Bone Marrow Stem Cells Comments Off on Rheumatoid Arthritis Stem Cell Therapy Market By Type (Allogeneic Mesenchymal Stem Cells, Bone Marrow Transplant, Adipose Tissue Stem Cells) and By… | October 16th, 2021