SALT LAKE CITY, Feb. 16, 2021 (GLOBE NEWSWIRE) -- Myriad Genetics, Inc. (NASDAQ: MYGN), a leader in genetic testing and precision medicine, announced that it will hold its quarterly earnings conference call for the period ending December 30, 2020 with investors and analysts at 4:30 p.m. EST on Tuesday, February 23, 2021. During the call, Paul J. Diaz, president and CEO, and R. Bryan Riggsbee, Chief Financial Officer, will provide a financial overview and business update of Myriad’s performance for the quarter.

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Myriad Genetics to Announce December 2020 Quarterly Financial Results on February 23, 2021

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YAVNE, Israel, Feb. 16, 2021 (GLOBE NEWSWIRE) -- MediWound Ltd. (Nasdaq: MDWD), a fully-integrated biopharmaceutical company bringing innovative therapies to address unmet needs in severe burn and wound management, today announced that the Company will release its financial results for the fourth quarter and year ended December 31, 2020 at 7:00 am Eastern Time on Thursday, February 25, 2021.

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MediWound to Report Fourth Quarter and Fiscal 2020 Financial Results and Host a Conference Call and Webcast on February 25, 2021

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Aleafia Health Announces $15 Million Bought Deal Offering of Units

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SAN DIEGO, Feb. 16, 2021 (GLOBE NEWSWIRE) -- Travere Therapeutics, Inc. (NASDAQ: TVTX) today announced it will report fourth quarter and full year 2020 financial results on Monday, March 1, 2021 after the close of the U.S. financial markets. The Company will host a conference call and webcast to discuss the financial results and provide a general business update at 4:30 p.m. ET.

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Travere Therapeutics to Report Fourth Quarter and Full Year 2020 Financial Results

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LEIDEN, Netherlands & CAMBRIDGE, Mass., Feb. 16, 2021 (GLOBE NEWSWIRE) -- ProQR Therapeutics N.V. (Nasdaq: PRQR) (the “Company”), a company dedicated to changing lives through the creation of transformative RNA therapies for inherited retinal diseases (IRDs), today announced that the Company will host an Expert Perspectives call on February 22, 2021 at 12:00pm EST. The call will feature a discussion between Aniz Girach, MD, Chief Medical Officer of ProQR Therapeutics and Paul Yang, MD, PhD about disease education and endpoints in Usher syndrome and non-syndromic Retinitis Pigmentosa (nsRP).  Areas of focus for the session will include which vision measures are most informative in the context of this disease setting, the role of patient baseline and disease progression, and an overview of the objectives of the Phase 1/2 Stellar trial of QR-421a.

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ProQR Announces Expert Perspectives Call on Disease Education and Endpoints in Usher Syndrome

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TORONTO, CHICAGO and MONTREAL, Feb. 16, 2021 (GLOBE NEWSWIRE) -- Medexus Pharmaceuticals Inc. (the “Company” or “Medexus”) (TSXV: MDP) (OTCQX: MEDXF) (Frankfurt: P731) announced today that it will be presenting at the Winter Wonderland Conference, hosted by The MicroCap Rodeo, being held virtually on February 16th – February 19th, 2021.

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CAMBRIDGE, Mass., Feb. 16, 2021 (GLOBE NEWSWIRE) -- Wave Life Sciences Ltd. (Nasdaq: WVE), a clinical-stage genetic medicines company committed to delivering life-changing treatments for people battling devastating diseases, announced today that Paul Bolno, MD, MBA, President and Chief Executive Officer, is scheduled to participate in an analyst-led fireside chat at the virtual 10th Annual SVB Leerink Global Healthcare Conference on Thursday, February 25, 2021 at 5:00 p.m. ET.

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CARLSBAD, Calif., Feb. 16, 2021 (GLOBE NEWSWIRE) -- GenMark Diagnostics, Inc. (NASDAQ: GNMK) (“GenMark” or the “Company”), a leading provider of automated, multiplex molecular diagnostic testing systems, today announced that the company plans to participate in the upcoming Cowen 41st Annual Health Care Conference.

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MARSEILLE, France, Feb. 17, 2021 (GLOBE NEWSWIRE) -- Innate Pharma SA (Euronext Paris: IPH – ISIN: FR0010331421; Nasdaq: IPHA) (“Innate” or the “Company”) announced today that members of its senior management team are scheduled to participate in the following upcoming virtual investor conference:

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Geneva, Switzerland, February 17, 2021 – Addex Therapeutics (SIX: ADXN and Nasdaq: ADXN), a clinical stage pharmaceutical company pioneering allosteric modulation-based drug discovery and development, today announced that it completed 2020 with a strong cash position of CHF18.7 million of cash and cash equivalents.

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ObsEva to Present at the SVB Leerink 10th Annual Global Healthcare Conference

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Basel, February 17, 2021 — Novartis today announced that it has entered into a grant agreement with the Bill & Melinda Gates Foundation. As part of the agreement, the foundation will provide funding support for the discovery and development of a single-administration, in vivo gene therapy to cure sickle cell disease (SCD). The project brings together Novartis drug discovery and gene therapy expertise with the Gates Foundation’s charitable objectives to expand access to healthcare in low-resource settings in an effort to address this potentially life-threatening genetic disease.

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Novartis and the Bill & Melinda Gates Foundation collaborate to discover and develop an accessible in vivo gene therapy for sickle cell disease

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PARIS and CAMBRIDGE, Mass., Feb. 17, 2021 (GLOBE NEWSWIRE) -- Biophytis SA (NasdaqGS: BPTS; Euronext Growth Paris: ALBPS), a clinical-stage biotechnology company focused on the development of therapeutics that are aimed at slowing the degenerative processes associated with aging and improving functional outcomes for patients suffering from age-related diseases, including severe respiratory failure in patients suffering from COVID-19, today announces that patient recruitment will begin in France and Belgium for Part 2 of its COVA Study assessing Sarconeos (BIO101) as a potential treatment for acute respiratory failure associated with COVID-19.

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Biophytis Announces Expansion of Patient Recruitment for Part 2 of the Phase 2-3 COVA Trial (“COVA Study”) Following Regulatory Authorities...

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Introduction

Extracellular vesicles (EVs) including exosomes, microvesicles, and apoptotic bodies are produced and released by almost all types of cell. EVs vary in size, properties, and secretion pathway depending on the originating cell.1,2 Exosomes are small EVs (sEVs) which are formed by a process of inward budding in early endosomes to form multivesicular bodies (MVBs) with an average size of 100 nm, and released into the extracellular microenvironment to transfer their components.3,4 Microvesicles are composed of lipid components of the plasma membrane and their sizes range from 1001000 nm, whereas apoptotic bodies result from programmed cell death.5 Initially, EVs were considered to maintain cellular waste through release of unwanted proteins and biomolecules; later, these organelles were considered important for intercellular communications through various cargo molecules such as lipids, proteins, DNA, RNA, and microRNAs (miRNAs).6 Previously, it was suggested that EVs play a critical role in normal cells to maintain homeostasis and prevent cancer initiation. Inhibition of EVs secretion causes accumulation of nuclear DNA in the cytoplasm, leading to apoptosis.1 The induction of apoptosis is the principal event of the reactive oxygen species (ROS) dependent DNA damage response.7,8

Several studies reported that exosomes are synthesized by means of two major pathways, the endosomal sorting complexes required for transport (ESCRT)-dependent and ESCRT-independent, and the processes are highly regulated by multiple signal transduction cascades.18 Exosomes released from the cell through normal exocytosis mechanisms are characterized by vesicular docking and fusion with the aid of SNARE complexes. Exosomes are considered to be organelle responsible for garbage disposal agents. However, at a later stage, these secretory bodies play a critical role in maintaining the physiological and pathological conditions of the surrounding cells by transferring information from donor cells to recipient cells. Exosome development begins with endocytosis to form early endosomes, later forming multivesicular endosomes (MVEs), and finally generating late endosomes by inward budding. MVEs merge with the cell membrane and release intraluminal endosomal vesicles that become exosomes into the extracellular space.9,10 Exosome biogenesis is dependent on various critical factors including the site of biogenesis, protein sorting, physicochemical aspects, and transacting mediators.11

Exosomes contain various types of cargo molecules including lipids, proteins, DNAs, mRNAs, and miRNAs. Most of the cargo is involved in the biogenesis and transportation ability of exosomes.12,13 Exosomes are released by fusion of MVBs with the cell membrane via activation of Rab-GTPases and SNAREs. Exosomes are abundant and can be isolated from a wide variety of body fluids and also cell culture medium.14 Exosomes contain tetraspanins that are responsible for cell penetration, invasion, and fusion events. Exosomes are released onto the external surface by the MVB formation proteins Alix and TSG101. Exosome-bound proteins, annexins and Rab protein, govern membrane transport and fusion whereas Alix, flotillin, and TSG101 are involved in exosome biogenesis.15,16 Exosomes contain various types of proteins such as integral exosomal membrane proteins, lipid-anchored outer and inner membrane proteins, peripheral surface and inner membrane proteins, exosomal enzymes, and soluble proteins that play critical roles in exosome functions.11

The functions of exosomes depend on the origin of the cell/tissue, and are involved in the immune response, antigen presentation programmed cell death, angiogenesis, inflammation, coagulation, and morphogen transporters in the creation of polarity during development and differentiation.1720 Ferguson and Nguyen reported that the unique functions of exosomes depend on the availability of unique and specific proteins and also the type of cell.21 All of these categories influence cellular aspects of proteins such as the cell junction, chaperones, the cytoskeleton, membrane trafficking, structure, and transmembrane receptor/regulatory adaptor proteins. The role of exosomes has been explored in different pathophysiological conditions including metabolic diseases. Exosomes are extremely useful in cancer biology for the early detection of cancer, which could increase prognosis and survival. For example, the presence of CD24, EDIL3, and fibronectin proteins on circulating exosomes has been proposed as a marker of early-stage breast cancer.22 Cancer-derived exosomes promoted tumor growth by directly activating the signaling pathways such as P13K/AKT or MAPK/ERK.23 Tumor-derived exosomes are significantly involved in the immune system, particularly stimulating the immune response against cancer and delivering tumor antigens to dendric cells to produce exosomes, which in turn stimulates the T-cell-mediated antitumor immune response.24 Exosomal surface proteins are involved in immunotherapies through the regulation of the tumor immune microenvironment by aberrant cancer signaling.25 A study demonstrated that exosomes have the potential to affect health and pathology of cells through contents of the vesicle.26 Exosomes derived from mesenchymal stem cells exhibit protective effects in stroke models following neural injury resulting from middle cerebral artery occlusion.27 The structural region of the exosome facilitate the release of misfolded and prion proteins, and are also involved in the propagation of neurodegenerative diseases such as Huntington disease, Alzheimers disease (AD), and Parkinsons disease (PD).28,29

Exosomes serve as novel intercellular communicators due to their cell-specific cargo of proteins, lipids, and nucleic acids. In addition, exosomes released from parental cells may interact with target cells, and it can influence cell behavior and phenotype features30 and also it mediate the horizontal transfer of genetic material via interaction of surface adhesion proteins.31 Exosomes are potentially serving as biomarkers due to the wide-spread and cell-specific availability of exosomes in almost all body fluids.13 Therefore, exosomes are exhibited as delivery vehicles for the efficient delivery of biological therapeutics across different biological barriers to target cells.3234

In this review, first, we comprehensively describe the factors involved in exosome biogenesis and the role of exosomes in intercellular signaling and cell-cell communications, immune responses, cellular homeostasis, autophagy, and infectious diseases. In addition, we discuss the role of exosomes as diagnostic markers, and the therapeutic and clinical implications. Finally, we discuss the challenges and outstanding developments in exosome research.

The extracellular vesicles play critical role in inter cellular communication by serving as vehicles for transfer of biomolecules. These vesicles are generally classified into microvesicles, ectosomes, shedding vesicles, or microparticles. MVs bud directly from the plasma membrane, whereas exosomes are represented by small vesicles of different sizes that are formed as the ILV by budding into early endosomes and MVBs and are released by fusion of MVBs with the plasma membrane (Figure 1). Invagination of late endosomal membranes results in the formation of intraluminal vesicles (ILVs) within large MVBs.35 Biogenesis of exosomes occurs in three ways including vesicle budding into discrete endosomes that mature into multivesicular bodies, which release exosomes upon plasma membrane fusion; direct vesicle budding from the plasma membrane; and delayed release by budding at intracellular plasma membrane-connected compartments (IPMCs) followed by deconstruction of IPMC neck(s).11 The mechanisms of biogenesis of exosomes are governed by various types of proteins including the ESCRT proteins Hrs, CHMP4, TSG101, STAM1, VPS4, and other proteins such as the Syndecan-syntenin-ALIX complex, nSMase2, PLD2, and CD9.14,3639 After formation, the MVB can either fuse with the lysosome to degrade its content or fuse with the plasma membrane to release the ILVs as exosomes. The release of exosomes to the extracellular milieu is driven by proteins of the Rab-GTPase family including RAB2B, 5A, 7, 9A, 11, 27, and 35. SNARE family proteins VAMP7 and YKT6 have also been implicated in the release.14,38,4042 Biogenesis of exosomes is influenced by several external factors including cell type, cell confluency, serum conditions, and the presence and absence of cytokines and growth factors. In addition, biogenesis is also regulated by the sites of exosomes, protein sorting, physico-chemical aspects, and trans-acting mediators (Figure 2). For example, THP-1 cells were cultured in RPMI-1640 cell culture medium supplemented with 10% FCS secreted low level of exosomes compared to cells grown on cell culture medium supplemented with 1% FCS (Figure 3). The exogenous factor like serum starvation influences biogenesis and secretion of exosomes.

Figure 1 Biogenesis and cargoes of exosomes.

Figure 2 Effect of various factors on biogenesis of exosomes.

Figure 3 Serum deprivation causes an increase of the number of cellular exosomes in THP-1 cells. Panel (A); 10% FCS. Panel (B); 1% FCS. Panel (C) Quantification of exosomes using DLS and NTA.

Exosome release depends on expression of Rab27 or Ral. For example, exosomes released from the MVB significantly decrease in cells depleted of Rab2741 or Ral.43 The most efficient EV-producing cell types have yet to be determined44 and few reports suggest that immature dendritic cells produce limited amounts of EVs45,46 whereas mesenchymal stem cells secrete vast amounts, relevant for the production of EV therapeutics on a clinical scale.47,48 A few proteins play a critical role in the biogenesis of EVs, such as Rab27a and Rab27b.49 Over expression of Rab27a and Rab27b produce significant amounts of EVs in cancer cells. For example, overexpression of Rab27a and Rab27b in breast cancer cells,50 hepatocellular carcinoma cells,51 glioma cells,52 and pancreas cancer cells53 produces significant levels of EVs. Although all types of cells secrete and release EVs, cancer cells seem to produce higher levels than normal cells.54 Furthermore, the presence of invadopodia that are docking sites for Rab27a-positive MVBs induces secretion of EVs, and also enhances secretion of EVs in cancer cells.55 Thus, inhibition of invadopodia formation greatly reduces exosome secretion into conditioned media. This evidence demonstrates that cancer cells potentially release more EVs than non-cancer cells.

The rate of origin of exosomes from the plasma membrane of stem cells is vigorous, at rates equal to the production of exosomes,56 which is consistent with a report suggesting that stem cells bud ~50100 nm-diameter vesicles directly from the plasma membrane.57 Plasma membrane-derived exosomes contain selectively enriched protein and lipid markers in leukocytes.58 Plasma membrane exosomal budding is also observed for glioblastoma exosomes.59 Conventional transmission electron microscopy revealed that certain cell types contain deep invaginations of the plasma membrane that are indistinguishable from MVBs.6062 Certain cell types secrete exosomes containing cargo proteins, which primarily bud from the plasma membrane, and exosome composition is determined predominantly by intracellular protein trafficking pathways, rather than by the distinct mechanisms of exosome biogenesis.63 Biogenesis of exosomes is regulated by syndecan heparan sulphate proteoglycans and their cytoplasmic adaptor syntenin. Syntenin interacts directly with ALIX through LYPX (n) L motifs.64 Glycosylation is an essential factor in the biogenesis of exosomes and N-linked glycosylation directs glycoprotein sorting into EMVs.65 Collectively, these reports suggest that exosomes are made at both plasma and endosome membranes rather than endosome alone. Oligomerization is a critical factor for exosomal protein sorting and it was found to be sufficient to target plasma membrane proteins to exosomes. High-order oligomeric proteins target them to exosomes.66 Further, plasma membrane anchors support exosomal protein budding. For example, budding of CD63 and CD9 from the plasma membrane is much more efficient than endosome-targeted budding of CD63 and CD9.63 Protein clustering is another factor that induces membrane scission.67

Physico-chemical properties determine budding efficiency and are crucial factors of exosome biogenesis, a fundamental process involving the budding of vesicles that are 30200 nm in size. In particular, lipids are critical players in exosome biogenesis, especially those able to form cone and inverse cone shapes. Generally, exosome membranes contain phosphatidylcholine (PC), phosphatidylserine (PS), phosphatidylethanolamine (PE), phosphatidylinositols (PIs), phosphatidic acid (PA), cholesterol, ceramides, sphingomyelin, glycosphingolipids, and a number of lower abundance lipids.68,69 Exosomes have a rich content of PE and PS, which increase budding efficiency and promote exosome genesis and release. PA promotes exosome biogenesis and PLD2 is involved in the budding of certain exosomal cargoes.70 Besides these factors, ceramide is an important lipid molecule regulating exosome biogenesis and facilitating membrane curvature, which is essential for vesicular budding. Inhibition of an enzyme that generates ceramide impairs exosome biogenesis.71

The next critical factor is trans-acting mediators that are involved in the biogenesis of exosomes through regulating plasma membrane homeostasis, intracellular protein trafficking pathways, MVB maturation and trafficking, IPMC biogenesis, vesicle budding, and scission.11 For example, Rab proteins regulate exosome biogenesis via endosomes and the plasma membrane by determining organelle membrane identity, recruiting mechanistic effectors, and mediating organelle dynamics.72 The functions of Rab proteins in the control and biogenesis of exosomes depends on cell type. MVB biogenesis is regulated by Rab27a, Rab27b, their effectors Slp4, Slac2b, and Munc13-4, and also Rab 35 and Rab 11.73 Loss of Rab27 function leads to a ~5075% drop in exosome production, and is also involved in assembling the plasma membrane microdomains involved in plasma membrane vesicle budding, by regulating plasma membrane PIP2 dynamics.74 Overall, Rab27 proteins control exosome biogenesis at both endosomes and plasma membranes. In addition, Rab35 also contributes to exosome biogenesis by regulating PIP2 levels of plasma membrane, and its loss leads to a reduction of exosome release by ~50%.75 Gurunathan et al76 reported that yeast produces two classes of secretory vesicles, low density and high density, and dynamin and clathrin are required for the biogenesis of these two different types of vesicle.

The Ral family is involved in the biogenesis of exosomes, and inhibition of Ral causes an accumulation of MVBs near the plasma membrane and a ~50% decrease in the vesicular secretion of exosomes and exosomal marker proteins.43 Ral GTPases function through various effectors proteins, including Arf6 and the phospholipase PLD2, which are involved in exosomal release of SDCs.37 The ESCRT complex machinery (0 through III) are involved in MVB biogenesis on a major level including membrane deformation, sealing, and repair during a wide array of processes. The major contributions of the ESCRT complex to the biogenesis of vesicles are the recognition and sequestration of ubiquitinated proteins to specific domains of the endosomal membrane via ubiquitin binding subunits of ESCRT-0. After interaction with the ESCRT-I and -II complexes, the total complex will then combine with ESCRT-III, a protein complex that is involved in promoting the budding process. Finally, following cleaving of the buds to form ILVs, the ESCRT-III complex separates from the MVB membrane using energy supplied by the sorting protein Vps4.77 In addition, other proteins such as Alix, which is associated with several ESCRT (TSG101 and CHMP4) proteins, are involved in endosomal membrane budding and abscission, as well as exosomal cargo selection via interaction with syndecan.39 Another important factor, autophagy, is critically involved in exosome secretion. Autophagy related (Atg) proteins coordinate initiation, nucleation, and elongation during autophagosome biogenesis in the presence of ESCRT-III components including CHMP2A and VPS4. For instance, the absence of Atg5 in cancer cells causes a reduction in exosome production.78 Conversely, CRISPR/Cas9-mediated knockout of Atg5 in neuronal cells increases the release of exosomes and exosome-associated prions from neuronal cells.79

Exosomes play a critical role in the physiologic regulation of mammary gland development and are important mediators of breast tumorigenesis.80 Biogenesis of exosomes occurs in all cell types; however, production depends on cell type. For example, breast cancer cells (BCC) produce increased numbers of exosomes compared to normal mammary epithelial cells. Studies revealed that patients with BC have increased numbers of MVs in their blood.81 Kavanagh et al reported that several fold changes were observed from exosomes isolated from triple negative breast cancer (TNBC) chemoresistant therapeutic induced senescent (TIS) cells compared with control EVs.82 TIS cells release significantly more EVs compared with control cells, containing chemotherapy and key proteins involved in cell proliferation, ATP depletion, and apoptosis, and exhibit the senescence-associated secretory phenotype (SASP). Cannabidiol (CBD), inhibits exosome and microvesicle (EMV) release in three different types of cancer cells including prostate cancer (PC3), hepatocellular carcinoma (HEPG2), and breast adenocarcinoma (MDA-MB-231). All three different cell lines show variability in the release of exosomes in a dose-dependent manner. These variabilities are all due to mitochondrial function, including modulation of STAT3 and prohibitin expression. This study suggests that the anticancer agent CBD plays critical role in EMV biogenesis.83 Sulfisoxazole (SFX) inhibits sEV secretion from breast cancer cells through interference with endothelin receptor A (ETA) through the reduced expression of proteins involved in the biogenesis and secretion of sEV, and triggers co-localization of multivesicular endosomes with lysosomes for degradation.84 Secreted EVs from human colorectal cancer cells contain 957 vesicular proteins. The direct protein interactions between cellular proteins play a critical role in protein sorting during EV formation. SRC signaling plays a major role in EV biogenesis, and inhibition of SRC kinase decreases the intracellular biogenesis and cell surface release of EVs.85 Proteomic analysis revealed that the exosomes released from imatinib-sensitive GIST882 cell line exhibit 764 proteins. The authors found that significant amount of proteins belong to protein release function and involved in the classical pathway and overlap to a high degree with proteins of exosomal origin.86 Exosomes secreted by antigen-presenting cells contain high levels of MHC class II proteins and costimulatory proteins, whereas exosomes released from other cell types lack these proteins.1,87

The biogenesis of exosomes depends on a percentage of confluency of approximately 6090%, which influences the yield and functions of EVs.44 Gal et al88 observed a 10-fold decreased level of cholesterol metabolism in confluent cell cultures compared to cells in the preconfluent state. The high level of cholesterol content in confluent cells leads to a decreased level of EVs in prostate cancer.68 The major reason behind for the reduced level of vesicle production is contact inhibition, which triggers confluent cells to enter quiescence and/or alters their characteristics compared to actively dividing cells.89,90 Exogenous stimulation could influence the condition of the cells including the phenotype and efficacy of secretion. Previously, several studies demonstrated that various external factors increase biogenesis of EVs such as Ca2+ ionophores,91 hypoxia,9294 and detachment of cells,95 whereas lipopolysaccharide reduces biogenesis and release of EVs.96 Furthermore, serum, which supports adherence of the cells, plays a critical role in the biogenesis of EVs.97 For example, FCS has noticeable effects on cultured cells; however, the effects depend on cell type and differentiation status.97,98 To avoid the immense amounts of vesicles present in FCS, the use of conditioned media has been suggested. Culture viability and health status of cells are important aspects for producing an adequate amount of vesicles with proper cargo molecules such as protein and RNA.99,100 Exogenous stress, such as starvation, can induce phenotypic alterations and changes in proliferation. These changes cause alterations in the cells metabolism and eventually lead to low yields.101,102

Cellular stresses, such as hypoxia, inflammation, and hyperglycemia, influence the RNA and protein content in exosomes. To examine these factors, the effects of cellular stresses on endothelial cells were studied.99 Endothelial cells were exposed to different types of cellular stress such as hypoxia, tumor necrosis factor- (TNF-)-induced activation, and high glucose and mannose concentrations. The mRNA and protein content of exosomes produced by these cells were compared using microarray analysis and a quantitative proteomics approach. The results indicated that endothelial cell-derived exosomes contain 1354 proteins and 1992 mRNAs. Several proteins and mRNAs showed altered levels after exposure of their producing cells to cellular stress. Interestingly, cells exposed to high sugar concentrations had altered exosome protein composition only to a minor extent, and exosome RNA composition was not affected. Low-intensity ultrasound-induced (LIUS) anti-inflammatory effects have been achieved by upregulation of extracellular vesicle/exosome biogenesis. These exosomes carry anti-inflammatory cytokines and anti-inflammatory microRNAs, which inhibit inflammation of target cells via multiple shared and specific pathways. A study suggested that exosome-mediated anti-inflammatory effects of LIUS are feasible and that these techniques are potential novel therapeutics for cancers, inflammatory disorders, tissue regeneration, and tissue repair.103 Another factor, called manumycin-A (MA), a natural microbial metabolite, was analyzed in exosome biogenesis and secretion in castration-resistant prostate cancer (CRPC) C4-2B, cells. The effect of MA on cell growth was observed, and the results revealed that there was no effect on cell growth. However, MA attenuated the ESCRT-0 proteins Hrs, ALIX, and Rab27a, and exosome biogenesis and secretion by CRPC cells. The inhibitory effect of MA on exosome biogenesis and secretion was primarily mediated via targeted inhibition of Ras/Raf/ERK1/2 signaling. These findings suggest that MA is a potential drug candidate for the suppression of exosome biogenesis and secretion by CRPC cells.104

Methods of isolation of exosomes play critical roles in functions and delivery. Although several methods such as ultracentrifugation, density gradient centrifugation, chromatography, filtration, polymer-based precipitation, and immunoaffinity have been adopted to isolate pure exosomes without contamination, there is still a lack of consistency and agreement.105 Isolation of exosomes along with non-exosomal materials and damaged exosomal membranes creates artifacts and alters the protein and RNA profiles. Since exosomes are obtained from a variety of sources, the composition of proteins/lipids influences the sedimentation properties and isolation. Thus, precise and consistent techniques are warranted for the isolation, purification, and application of exosomes.

Although several functions of exosomes have been explored, the precise function of exosomes remains a mystery. Historically, exosomes have been known to function as cellular garbage bags, recyclers of cell surface proteins, cellular signalers, intercellular signaling and cell-cell communications, immune responses, cellular homeostasis, autophagy, and infectious diseases.106 (Figure 4) ECVs are secreted cell-derived membrane particles involved in intercellular signaling and cell-cell communications, and contain immense bioactive information. Most cell types produce exosomes and release these into the extracellular environment, circulating through different bodily fluids such as urine, blood, and saliva and transferring their cargo to recipient cells. These vesicles play a significant role in various pathological conditions, such as different types of cancer, neurodegenerative diseases, infectious diseases, pregnancy complications, obesity, and autoimmune diseases, as reviewed elsewhere.107 Exosomes play a significant role in intercellular communication between cells by interacting with target cells via endocytosis.108 More specifically, exosomes are involved in cancer development, survival and metastasis of tumors, drug resistance, remodeling of the extracellular matrix, angiogenesis, thrombosis, and proliferation of tumor cells.94,109111 Exosomes contribute significantly to tumor vascularization and hypoxia-mediated inter-tumor communication during cancer progression, and premetastatic niches, which are significant players in cancer.16,94,109,112 Exosomes derived from hepatic epithelial cells increase the expression of enhancer zeste homolog 2 (EZH2) and cyclin-D1, and subsequently promotes G1/S transition.113

Figure 4 Multifunctional aspects biological functions of exosomes.

Conventionally, cells communicate with adjacent cells through direct cell-cell contact through gap junctions and cell surface protein/protein interactions, whereas cells communicating with distant cells do so through secreted soluble factors, such as hormones and cytokines, to facilitate signal propagation.114 Cells also communicate through electrical and chemical signals.115 Several studies have suggested that exosomes play vital roles in intercellular communication by serving as vehicles for transferring various cellular constituents, such as proteins, lipids, and nucleic acids, between cells.6,116118 Exosomes function as exosomal shuttle RNAs in which some exosomal RNAs from donor cells functions in recipient cells,6 a form of genetic exchange. Recently, researchers found that cells communicating with other cells through exosomes carrying cell-specific cargoes of proteins, lipids, and nucleic acids may employ novel intercellular communication mechanisms.30 Exosomes exert influences through various mechanistic approaches, such as direct stimulation of target cells via surface-bound ligands; transfer of activated receptors to recipient cells; and epigenetic reprogramming of recipient cells.119,120 Exosomes play critical roles in immunoregulation, including antigen presentation, immune activation, immune suppression, and immune tolerance via exosome-mediated intercellular communication. Mesenchymal stem cell (MSC)-derived exosomes play significant roles in wound healing processes.121 Exosomes from platelet-rich plasma (PRP) inhibit the release of TNF-. PRP-Exos significantly decreases the apoptotic rate of osteoarthritis (OA) chondrocytes compared with activated PRP (PRP-As).122 Extracellular vesicle (ECV)-modified polyethylenimine (PEI) complexes enhance short interfering RNA (siRNA) delivery by forming non-covalent complexes with small RNA molecules, including siRNAs and anti-miRs, in both conditions, in vitro and in vivo.123 Non-GSC glioma cells were treated with GSC-released exosomes. The results showed that GSC-released exosomes increase proliferation, neurosphere formation, invasive capacities, and tumorigenicity of non-GSC glioma cells through the Notch1 signaling pathway and stemness-related protein expressions.124

Exosomal miR-1910-3p promotes proliferation and migration of breast cancer cells in vitro and in vivo through downregulation of myotubularin-related protein 3 and activation of the nuclear factor-B (NF-B) and wnt/-catenin signaling pathway, and promotes breast cancer progression.125 Human hepatic progenitor cell (CdH)-derived exosomes (EXOhCdHs) play a crucial role in maintaining cell viability and inhibit oxidative stress-induced cell death. Experimental evidence suggests that inhibition of exosome secretion treatment with GW4869 results in the acceleration of reactive oxygen species (ROS) production, thereby causing a decrease in cell viability.126 Tumor-derived EXs (TDEs) are vehicles that enable communication between cells by transferring bioactive molecules, also delivering oncogenic molecules and containing different molecular cargoes compared to EXs delivered from normal cells. They can therefore be used as non-invasive biomarkers for the early diagnosis and prognosis of most cancers, including breast and ovarian cancers.127 Exosomes released by ER-stressed HepG2 cells significantly enhance the expression levels of several cytokines, including IL-6, monocyte chemotactic protein-1, IL-10, and tumor necrosis factor- in macrophages. ER stress-associated exosomes mediate macrophage cytokine secretion in the liver cancer microenvironment, and also indicate the potential of treating liver cancer via an ER stress-exosomal-STAT3 pathway.128 Mesenchymal stem cell-derived exosomal miR-223 protects neuronal cells from apoptosis, enhances cell migration and increases miR-223 by targeting PTEN, thus activating the PI3K/Akt pathway. In addition, exosomes isolated from the serum of AD patients promote cell apoptosis through the PTEN-PI3K/Akt pathway and these studies indicate a potential therapeutic approach for AD.129 A mouse model of diabetes demonstrated that mesenchymal stromal cell-derived exosomes ameliorate peripheral neuropathy through increased nerve conduction velocity. In addition, MSC-derived exosomes substantially suppress proinflammatory cytokines.130

Exosomes derived from activated astrocytes promote microglial M2 phenotype transformation following traumatic brain injury (TBI). miR-873a-5p significantly inhibits LPS-induced microglial M1 phenotype transformation.131 Several studies reported that exosomes are involved in cancer progression and metastasis; however, this depends on the type of cells the exosomes were derived from. For example, human umbilical vein endothelial cells (HUVEC) were treated with exosomes derived from HeLa cells (ExoHeLa), and the expression of tight junctions (TJ) proteins, such as zonula occludens-1 (ZO-1) and Claudin-5, was significantly reduced compared with exosomes from human cervical epithelial cells. Thus, permeability of the endothelial monolayer was increased after the treatment with ExoHeLa. Mice studies have shown that injection of ExoHeLa into mice increased vascular permeability and tumor metastasis. The results from this study demonstrated that HeLa cell-derived exosomes promote metastasis by triggering ER stress in endothelial cells and break down endothelial integrity. Such effects of exosomes are microRNA-independent.132 Exosomes mediate the gene expression of target cells and regulate pathological and physiological processes including promoting angiogenesis, inhibiting ventricular remodeling and improving cardiac function, as well as inhibiting local inflammation and regulating the immune response. Accumulating evidence shows that exosomes possess therapeutic potential through their anti-apoptotic and anti-fibrotic roles.

The functions of exosomes in immune responses are well established and do not cause any severe immune responses. A mouse study demonstrated that administration of a low dose of mouse or human cell-derived exosomes for extended periods of time caused no severe immune reactions.133 The function of exosomes in immune regulation is regulated by the transfer and presentation of antigenic peptides. Exosomes contain antigen-presenting cells (APCs) carrying peptide MHC-II and costimulatory signals and directly present the peptide antigen to specific T cells to induce their activation.134 For example, intradermal injection of APC-derived exosomes with MHC-II loaded with tumor peptide delayed tumor progression and growth.135 Exosome-derived immunogenic peptides activate immature mouse dendritic cells and indirectly activate APCs, and induce specific CD4+ T cell proliferation.136 Exosomes containing IFNa and IFNg, tumor necrosis factor a (TNFa), and IL from macrophages promoted dendritic cell maturation, CD4+ and CD8+ T cell activation, and the regulation of macrophage IL expression.137 The cargo of exosomes, such as DNA and miRNA, regulate the innate and adaptive immune responses. Exosomes are able to regulate the immune response by controlling gene expression and signaling pathways in recipient cells through transfer of miRNAs, and eventually control dendritic cell maturation.138 Exosomes containing miR-212-3p derived from tumors down-regulate the MHC-II transcription factor RFXAP (regulatory factor X associated protein) in dendritic cells, possibly promoting immune evasion by cancer cells.139 Exosomes containing miR-222-3p down regulate expression of SOCS3 (suppressor of cytokine signaling 3) in monocytes, which is involved in STAT3-mediated M2 polarization of macrophages.140 In mice, exosomes stimulate adaptive immune responses, including the activation of dendritic cells, with the uptake of breast cancer cell-derived exosomal genomic DNA and activation of cGAS-STING signaling and antitumor responses.141 The priming of dendritic cells is associated with the uptake of exosomal genomic and mitochondrial DNA (mtDNA) from T cells, inducing type I IFN production by cGAS-STING signaling.142 Inhibition of EGFR leads to increased levels of DNA in the exosomes and induces cGAS-STING signaling in dendritic cells, contributing to the overall suppression of tumor growth.143 Conversely, uptake of tumor-derived exosomal DNA by circulating neutrophils was shown to enhance the production of tissue factor and IL-8, which play a role in promoting tumor inflammation and paraneoplastic events.144 Melanoma-derived exosomes containing PD-L1 (programmed cell death ligand 1) suppress CD8+ T cell antitumor function and cancer cell-derived exosomes block dendritic cell maturation and migration in a PD-L1-dependent manner. Engineered cancer cell-derived exosomes promote dendritic cell maturation, resulting in increased proliferation of T cells and antitumor activity.145147

Inflammation is an important process for maintaining homeostasis in cellular systems. Systemic inflammation is an essential component in the pathogenesis of several diseases.148,149 Exosomes seem to play a crucial role in inflammation processes through cargo molecules, such as miRNA and proteins, which act on nearby as well as distant target tissues. Exosomes play a vital role in intercellular communication between cells via endocytosis and are associated with modulation of inflammation, coagulation, angiogenesis, and apoptosis.20,150153 Exosomes derived from dendritic cells, B lymphocytes, and tumor cells release exosomes that can regulate immunological memory through the surface expression of antigen-presenting MHC I and MHC II molecules, and subsequently elicit T cell activation and maturation.134,137,154156 Exosomes play a crucial role in carrying and presenting functional MHC-peptide complexes to modulate antigen-specific CD8+ and CD4+ responses.157,158 Exosomes containing miR-Let-7d influence the growth of T helper 1 (Th1) cells and inhibit IFN- secretion.159 Exosomes derived from choroid plexus epithelial cells containing miR-146a and miR-155 upregulate the expression of inflammatory cytokines in astrocytes and microglia.160 Exosomes containing miR-181c suppress the expression of Toll-like receptor 4 (TLR-4) and subsequently lower TNF- and IL-1 levels in burn-induced inflammation.161 Exosomal miR-155 from bone marrow cells (BMCs) increases the level of TNF- and subsequently enhances innate immune responses in chronic inflammation.162 Exosomes containing miR-150-5p and miR-142-3p derived from dendritic cells (DCs) increase expression of interleukin 10 (IL-10) and a decrease in IL-6 expression.163 Exosomal miR-138 can protect against inflammation by decreasing the expression level of NF-B, a transcription factor that regulates inflammatory cytokines such as TNF- and IL-18.164 HIF-1-inducing exosomal microRNA-23a expression from tubular epithelial cells mediates the cross talk between tubular epithelial cells and macrophages, promoting macrophage activation and triggering tubulointerstitial inflammation.165 A rat model study demonstrated that bone marrow mesenchymal stem cell (BMSC)-derived exosomes reduced inflammatory responses by modulating microglial polarization and maintaining the balance between M2-related and M1-related cytokines.165 Melatonin-stimulated mesenchymal stem cell (MSC)-derived exosomes improve diabetic wound healing through regulating macrophage M1 and M2 polarization by targeting the PTEN/AKT pathway, and significantly suppressed the pro-inflammatory factors IL-1 and TNF- and reduced the relative gene expression of IL-1, TNF-, and iNOS. Increasing levels of anti-inflammatory factor IL-10 are associated with increasing relative expression of Arg-1.166

Immunomodulators are essential factors for the prevention and treatment of disorders occurring due to an over high-spirited immune response, such as the SARS-CoV-2-triggered cytokine storm leading to lung pathology and mortality seen during the ongoing viral pandemic.167 MSC-secreted extracellular vesicles exhibit immunosuppressive capacity, which facilitates the regulation of the migration, proliferation, activation, and polarization of various immune cells, promoting a tolerogenic immune response while inhibiting inflammatory responses.168 Collagen scaffold umbilical cord-derived mesenchymal stem cell (UC-MSC)-derived exosomes induce collagen remodeling, endometrium regeneration, increasing the expression of the estrogen receptor /progesterone receptor, and restoring fertility. Furthermore, exosomes modulate CD163+ M2 macrophage polarization, reduce inflammation, increase anti-inflammatory responses, facilitate endometrium regeneration, and restore fertility through the immunomodulatory functions of miRNAs.169 Exosomes released into the airways during influenza virus infection trigger pulmonary inflammation and carry viral antigens and it facilitate the induction of a cellular immune response.170 Shenoy et al171 reported that exosomes derived from chronic inflammatory microenvironments contribute to the immune suppression of T cells. These exosomes arrest the activation of T cells stimulated via the T cell checkpoint (TCR). Exosomes secreted by normal retinal pigment epithelial cells (RPE) by rotenone-stimulated ARPE-19 cells induce apoptosis, oxidative injury, and inflammation in ARPE-19 cells. Exosomes secreted under oxidative stress induce retinal function damage in rats and upregulate expression of Apaf1. Overexpression of Apaf1 in exosomes secreted under oxidative stress (OS) can cause the inhibition of cell proliferation, increase in apoptosis, and elicitation of inflammatory responses in ARPE-19 cells. Exosomes derived from ARPE-19 cells under OS regulate Apaf1 expression to increase apoptosis and to induce oxidative injury and inflammatory response through a caspase-9 apoptotic pathway.172 Collectively, these findings highlight the critical role of exosomes in inflammation and suggest the possibility of utilizing exosomes as an inducer to attenuate inflammation and restore impaired immune responses in various diseases including cancer.

The endomembrane system of eukaryotic cells is a complex series of interconnected membranous organelles that play vital roles in protecting cells from adverse conditions, such as stress, and maintaining cell homeostasis during health and disease.173 To preserve cellular homeostasis, higher eukaryotic cells are equipped with various potent self-defense mechanisms, such as cellular senescence, which blocks the abnormal proliferation of cells at risk of neoplastic transformation and is considered to be an important tumor-suppressive mechanism.174,175 Exosomes contribute to reduce intracellular stress and preservation of cellular homeostasis through clearance of damaged or toxic material, including proteins, lipids, and even nucleic acids. Therefore, exosomes serve as quality controller in cells.176 The vesicular transport system plays pivotal roles in the maintenance of cell homeostasis in eukaryote cells, which involves the cytoplasmic trafficking of biomolecules inside and outside of cells. Several types of membrane-bound organelles, such as the Golgi apparatus, endoplasmic reticulum (ER), endosomes and lysosomes, in association with cytoskeleton elements, are involved in the intracellular vesicular system. Molecules are transported through exocytosis and endocytosis to maintain homeostasis through the intracellular vesicular system and regulate cells responses to the internal and external environment. To maintain homeostasis and protect cells from various stress conditions, autophagy is an intracellular vesicular-related process that plays an important role through the endocytosis/lysosomal/exocytosis pathways through degradation and expulsion of damaged molecules out of the cytoplasm.177179 Autophagy, as an intracellular waste elimination system, is a synchronized process that actively participates in cellular homeostasis through clearance and recycling of damaged proteins and organelles from the cytoplasm to autophagosomes, and then to lysosomes.38,180182 Cells maintain homeostasis by autophagosomes, which are vesicles derived from autophagic and endosomal compartments. These processes are involved in adaption to nutrient deprivation, cell death, growth, and tumor progression or suppression. Autophagy flux contributes to maintaining homeostasis in the tumor microenvironment of endothelial cells. To support this concept, a study provided evidence suggesting that depletion of Atg5 in ECs could intensify the abnormal function of tumor vessels.183 Exosome secretion plays a crucial role in maintaining cellular homeostasis in exosome-secreting cells. As a consequence of blocking exosome secretion, nuclear DNA accumulates in the cytoplasm, thereby causing the activation of cytoplasmic DNA sensing machinery. Blocking exosome secretion aggravates the innate immune response, leading to ROS-dependent DNA damage responses and thus inducing senescence-like cell-cycle arrest or apoptosis in normal human cells. Thus, cells remove harmful cytoplasmic DNA, protecting them from adverse effects.182 Salomon and Rice reported that the involvement of exosomes in placental homeostasis and pregnancy disorders. EVs of placental origin are found in a variety of body fluids including urine and blood. Moreover, the number of exosomes throughout gestation is higher in complications of pregnancy, such as preeclampsia and gestational diabetes mellitus, compared to normal pregnancies.184

The endolysosomal system is critically involved in maintaining homeostasis through the highly regulated processes of internalization, sorting, recycling, degradation, and secretion. For example, endocytosis allows the internalization of various receptor proteins into cells, and vesicles formed from the plasma membrane fuse and deliver their membrane and protein content to early endosomes. Similarly, significant amounts of internalized content are recycled back to the plasma membrane via recycling endosomes,76 while the remaining material is sequestered in ILVs in late endosomes, also known as multivesicular bodies.185,186 Tetraspanin proteins, such as CD63 and CD81, are regulators of ILV formation. Once ILVs are formed, MVBs can degrade their cargo by fusing with lysosomes or, alternatively, MVBs can secrete their ILVs by fusing with the plasma membrane and release their content into extracellular milieu.187190 Exosomes play an important role in regulating intracellular RNA homeostasis by promoting the release of misfolded or degraded RNA products, and toxic RNA products. Y RNAs are involved in the degradation of structured and misfolded RNAs. Further studies have demonstrated that proteins involved in RNA processing are abundant in exosomes, and the half-lives of secreted RNAs are almost twice as short as those of intracellular mRNAs. These studies suggest that cells maintain intracellular RNA homeostasis through the release of distinct RNA species in extracellular vesicles.191193 Exosomes reduce cholesterol accumulation in Niemann-Pick type C disease, a lysosomal storage disease in which cells accumulate unesterified cholesterol and sphingolipids within the endosomal and lysosomal compartment.194

Autophagy is the intracellular vesicular-related process that regulates the cell environment against pathological and stress conditions. In order to maintain homeostasis and protect the cells against stress conditions, internal vesicles or secreted vesicles serve as a canal to degrade and expel damaged molecules out of the cytoplasm.38,181,182 Autophagy protects the cell from various stress conditions and maintains cellular homeostasis, regulating cell survival and differentiation through clearance and recycling of damaged proteins and organelles from the cytoplasm to autophagosomes, and then to lysosomes.180 Several studies have demonstrated that proteins are involved in controlling tumor cell function and fate, and mediate crosstalk between exosome biogenesis and autophagy. Coordination between exosome-autophagy networks serves as a tool to conserve cellular homeostasis via the lysosomal degradative pathway and/or secretion of cargo into the extracellular milieu.176,195 Autophagy is a multi-step process that occurs by initiation, membrane nucleation, maturation and finally the fusion of autophagosomes with lysosomes. The autophagy process is not only linked with endocytosis but is also linked with the biogenesis of exosomes. For example, subsets of the autophagy machinery involved in the biogenesis of exosomes and the autophagic process itself appear dispensable.78,196 Crosstalk between exosomal and autophagic pathways has been reported in a growing number of diseases. Proteomic studies were performed to analyze the involvement of key proteins in the interconnection between exosome and autophagy pathways. They found that almost all proteins were identified; however, their involvement differed between them. Among 100 proteins, four proteins were highly ranked including HSPA8 (3/100), HSP90AA1 (8/100), VCP (24/100), and Rab7A (81/100). These data suggest an interconnection between the exosome and autophagy.197,198 Endosomal autophagy plays a significant role in the interconnection between exosomes and autophagy. Stress is a major factor for autophagy. In particular, the starvation of cells is a key inducer of autophagy, and induces enlargement of MVB structures and a co-localization of Rab11 and LC3 in these structures, an indication that autophagy-related processes are associated with the MVB.199 The sorting of autophagy-related cargo into MVBs is dependent on Hsc70 (HSPA8), VPS4, and TSG101, and independent on LAMP-2A, thereby excluding a role for, the lysosome.200 Several proteins are involved in the regulation and biogenesis of secretory autophagy compartments such as GRASPs, LC3, Rab8a, ESCRTs, and SNAREs, along with several Atg proteins.181,201,202 Autophagosomes could fuse with MVBs to form amphisomes and release vesicles to the external environment.203

Autophagy and exosome biogenesis and function are interconnected by microRNA. Over-expression of miR-221/222 inhibits the level of PTEN and activates Akt signaling, and subsequently reduces the expression of hallmarks that positively relate to autophagy including LC3, ATG5 and Beclin1, and increases the expression of SQSTM1/p62.204 MiR-221/222 from human aortic smooth muscle cell (HAoSMC)-derived exosomes inhibit autophagy in HUVECs by modulating the PTEN/Akt signaling pathway. miRNA-223 attenuates hypoxia-induced apoptosis and excessive autophagy in neonatal rat cardiomyocytes and H9C2 cells via the Akt/mTOR pathway, by targeting poly(ADP-ribose) polymerase 1 (PARP-1) through increased autophagy via the AMPK/mTOR and Akt/mTOR pathways205 ATG5 mediates the dissociation of vacuolar proton pumps (V1Vo-ATPase) from MVBs, which prevents acidification of the MVB lumen and allows MVB-PM fusion and exosome release. Accordingly, knockout of ATG5 or ATG16L1 significantly reduces exosome release and attenuates the exosomal enrichment of lipidated LC3B. These findings demonstrate that autophagic mechanisms possibly regulate the fate of MVBs and subsequent exosome biogenesis.78 Bone marrow MSC (BMMSC)-derived exosomes contain a high level of miR-29c, which regulates autophagy under hypoxia/reoxygenation (H/R) conditions.206 Human umbilical cord MSC-derived exosomes (HucMDEs) promote hepatic glycolysis, glycogen storage, and lipolysis, and reduce gluconeogenesis. Additionally, autophagy potentially contributes to the effects of HucMDE treatment and increases formation of autophagosomes and the autophagy marker proteins BECN1, MAP, and 1LC3B. These findings suggest that HucMDEs improve hepatic glucose and lipid metabolism in T2DM rats by activating autophagy via the AMPK pathway.207 Liver fibrosis is a serious disorder caused by prolonged parenchymal cell death, leading to the activation of fibrogenic cells, extracellular matrix accumulation, and eventually liver fibrosis. Exosomes derived from adipose-derived mesenchymal stem cells (ADSCs) have been used to deliver circular RNAs mmu_circ_0000623 to treat liver fibrosis. The findings from this study suggest that Exos from ADSCs containing mmu_circ_0000623 significantly suppress CCl4-induced liver fibrosis by promoting autophagy activation. Autophagy inhibitor treatment significantly reverses the treatment effects of Exos.208 Inhibition of autophagy by PDGF and its downstream molecule SHP2 (Src homology 2-containing protein tyrosine phosphatase 2) increased hepatic stellate cell (HSC)-derived EV release. Disruption of mTOR signaling abolishes PDGF-dependent EV release. Activation of mTOR signaling induces the release of MVB-derived exosomes by inhibiting autophagy, as well as microvesicles, through activation of ROCK1 signaling. Furthermore, deletion of SHP2 attenuates CCl4 or BDL-induced liver fibrosis.209 The therapeutic effects of exosomes containing high concentrations of mmu_circ_0000250 were analyzed in diabetic mice. The findings indicated that a high concentration of mmu_circ_0000250 had a better therapeutic effect on wound healing when compared with wild-type exosomes from ADSCs. The results also showed that exosome treatment with mmu_circ_0000250 increased angiopoiesis in wounded skin and suppressed apoptosis by inducing miR-128-3p/SIRT1-mediated autophagy.210 A study showed that mice treated with differentiated cardiomyocyte (iCM) exosomes exhibited significant cardiac improvement post-myocardial infarction, with significantly reduced apoptosis and fibrosis. Apoptosis was associated with reduced levels of hypoxia and inhibition of exosome biogenesis. iCM-exosome-treated groups showed upregulation of autophagosome production and autophagy flux. Hence, these findings indicate that iCM-Ex can improve post-myocardial infarction cardiac function by regulating autophagy in hypoxic cardiomyocytes.211 Exosomes of hepatocytes play a crucial role in inhibiting hepatocyte apoptosis and promoting hepatocyte regeneration. Mesenchymal stem cell-derived hepatocyte-like cell exosomes (MSC-Heps-Exo) were injected into a mouse hepatic Ischemia/reperfusion (I/R) I/R model through the tail. The results demonstrated that MSC-Heps-Exo effectively relieve hepatic I/R damage, reduce hepatocyte apoptosis, and decrease liver enzyme levels. A possible mechanism of reduced hepatic ischemia/reperfusion injury is the enhancement of autophagy.212

Exosomes play a critical role in viral infections, particularly of retroviruses and retroviruses, and use preexisting pathways for intracellular protein trafficking and formation of infectious particles. Exosomes and viruses share several features including biogenesis, uptake by cells, and the intracellular transfer of RNAs, mRNAs, and cellular proteins. Some features are different, including self-replication after infection of new cells, regulation of viral expression, and complex viral entry mechanisms.213,214 Exosomes secreted from virus-infected cells carry mostly cargo molecules such as viral proteins, genomic RNA, mRNA, miRNA, and genetic regulatory elements.215218 These cargo molecules are involved in the alteration of recipient cell behavior, regulating cellular responses, and enabling infection by various types of viruses such as human T-cell lymphotropic virus (HTLV), hepatitis C virus (HCV), dengue virus, and human immunodeficiency virus (HIV).215 Exosomes communicate with host cells through contact between exosomes and their recipient cells, via different kinds of mechanisms. Initially, the transmembrane proteins of exosomes build a network directly with the signaling receptors of target cells and then join with the plasma membrane of recipient cells to transport their content to the cytosol. Finally, the exosomes are incorporated into the recipient cells.219221 A report suggested that disruption of exosomal lipid rafts leads to the inhibition of internalization of exosomes.95 Exosomes derived from HIV-infected patients contain the trans-activating response element, which is responsible for HIV-1 replication in recipient cells through downregulation of apoptosis.222 While exosomes serving as carrier molecules, exosomes contain miRNAs that induce viral replication and immune responses either by direct targeting of viral transcripts or through indirect modulation of virus-related host pathways. In addition, exosomes have been found to act as nanoscale carriers involved in HIV pathogenesis. For example, exosomes enhance HIV-1 entry into human monocytic and T cell lines through the exosomal tetraspanin proteins CD9 and CD81.223 Influenza virus infection causes accumulation of various types of microRNAs in bronchoalveolar lavage fluid, which are responsible for the potentiation of the innate immune response in mouse type II pneumocytes. Serum of influenza virus-infected mice show significant levels of miR-483-3p, which increases the expression of proinflammatory cytokine genes and inflammatory pathogenesis of H5N1 influenza virus infection in vascular endothelial cells.224 Exosomes are involved in the transmission of inflammatory, apoptotic, and regenerative signals through RNAs. Chen et al investigated the potential functions of exosomal RNAs by RNA sequencing analysis in exosomes derived from clinical specimens of healthy control (HC) individuals and patients with chronic hepatitis B (CHB) and acute-on-chronic liver failure caused by HBV (HBV-ACLF). The results revealed that the samples contained unique and distinct types of RNAs in exosomes.225 Zika virus (ZIKV) infection causes severe neurological malfunctions including microcephaly in neonates and other complications associated with Guillain-Barr syndrome in adults. Interestingly, ZIKV uses exosomes as mediators of viral transmission between neurons and increases production of exosomes from neuronal cells. Exosomes derived from ZIKV-infected cells contained both ZIKV viral RNA and protein(s) which are highly infectious to nave cells. ZIKV uses neutral Sphingomyelinase (nSMase)-2/SMPD3 to regulate production and release of exosomes.226

During infections, viruses replicate in host cells through vesicular trafficking through a sequence of complexes known as ESCRT, and assimilate viral constituents into exosomes. Exosomes encapsulate viral antigens to maximize infectivity by hiding viral genomes, entrapping the immune system, and maximizing viral infection in uncontaminated cells. Exosomes can be used as a source of viral antigens that can be targeted for therapeutic use. A Variety of infectious diseases caused by viruses such as HCV, ZIKV, West Nile virus (WNV), and DENV enter into the host cells using clathrin-mediated or receptor-mediated endocytosis. For example, HCV infects host cells by specific targeting of cells through cellular contact, and hepatocyte-derived exosomes that contain HCV RNA can stimulate innate immune cells.217,227230 Exosomes show structural and molecular similarity to HIV-1 and HIV-2, which are enclosed by a lipid bilayer, and in the vital features of size and density, RNA species, and macro biomolecules including carbohydrates, lipids, and proteins. HIV-infected cells release enriched viral RNAs containing exosomes derived from HIV-infected cells and are enhanced with viral RNAs and Nef protein.6,38,231236 Izquierdo-Useros et al reported that both exosomes and HIV-1 express sialyllactose-containing gangliosides and interact with each other via sialic-acid-binding immunoglobulin-like lectins (Siglecs)-1. Siglecs-1 stimulates mature dendritic cell (mDC) capture and storage of both exosomes and HIV-1 in mDCs.237 Exosomes released from HIV-infected T cells contain transactivation response (TAR) element RNA, which stimulate proliferation, migration, and invasion of oral/oropharyngeal and lung cancer cells.238 Nuclear VP40 from Ebola virus VP40 upregulates cyclin D1 levels, resulting in dysregulated cell cycle and EV biogenesis. Synthesized extracellular vesicles contain cytokines and EBOV proteins from infected cells, which are responsible for the destruction of immune cells during EBOV pathogenesis.239 HIV enters into the host cells through human T-cell immunoglobin mucin (TIM) proteins. TIMs are a group of proteins (TIM-1, TIM-3, and TIM-4) that promote phagocytosis of apoptotic cells.240 TIM-4 is involved in HIV-1 exosome-dependent cellular entry mechanisms. Substantiating this hypothesis, neural stem cell (NSC)-derived exosomes containing TIM-4 protein increase HIV-1 exosome-dependent cellular entry into host cells, and antibody against TIM4 inhibits exosome-mediated entry of HIV in various types of cell.241

Exosomes show immense promise in biomedical applications due to their potential in drug delivery, the carriage of biomolecular markers of many diseases, and cellular protection. In addition, they can be used in non-invasive diagnostics or minimum invasive diagnostics.150 Detection of biomarkers is vital for early diagnosis of cancer and also critical for treatment. Several studies have documented the importance of exosomes in a variety of diseases, although further examination of the biology and functions of exosomes is warranted due to the continuing emergence of new diseases in the present world. The complex cargo of exosomes facilitates the exploration of a variety of diagnostic windows into disease detection, monitoring, and treatment. Exosomes are found in all biological fluids and are secreted by all cells, rendering them attractive for use through minimally invasive liquid biopsies, and they have the potential for use in longitudinal sampling to follow disease progression.242 Exosomes are produced and secreted by almost all body fluids, including blood, urine, saliva, breast milk, cerebrospinal fluid, semen, amniotic fluid, and ascites. These exosomes contain micro RNAs, proteins, and lipids serving as diagnostic markers.120 Exosomes are used in diagnostic applications in various kinds of diseases, such as cardiovascular diseases (CVDs),243 diseases of the central nervous system (CNS),244 cancer,245 and other prominent diseases including in the liver,246 kidney,247 and lung.248 Exosomes are potentially used to detect cancer-associated mutations in serum and also for the transfer of genomic DNA from donor cells to recipient cells.249 Exosomes carrying specific miRNAs or groups of miRNAs can be used as diagnostic markers to detect cancer. For example, exosomes containing oncogenic Kras, which have tumor-suppressor miRNAs-100, seem to have high diagnostic value, which could facilitate the differentiation of the expression pattern between cancer cells and normal cells.250,251 Similarly, miR-21 is considered to be diagnostic marker for various types of cancer including glioblastomas and pancreatic, colorectal, colon, liver, breast, ovarian, and esophageal cancers.252 Tumor suppressor miRNAs, such as miR-146a and miR-34a, function as diagnostic tools to detect liver, breast, colon, pancreatic, and hematologic malignancies.251 Exosomes containing GPC1 (glypican 1) are used as diagnostic markers to detect pancreatic, breast, and colon cancer.253,254

Exosomes play critical roles in various types of disease, and particularly in cancer progression and resistance to therapy. The unique biogenesis of exosomes and their biological features have generated excitement for their potential use as biomarkers for cancer.255 Generally, exosomes are produced and secreted by most cells and contain all the biological components of a cell. Hence, exosomes are found in all biological fluids and provide excellent opportunities for use as biomarkers.242 Surface proteins of exosomes are involved in the regulation of the tumor immune microenvironment and the monitoring of immunotherapies. Hence, exosome proteins play a critical role in cancer signaling.256 Exosomes from patients with metastatic pancreatic cancer show a higher mutant Kras allele frequency than exosomes from patients with local disease. In addition, the exosomes also accumulate a significantly higher level of cancer cell-specific DNA such as cytoplasmic DNA.8,257 Exosomes protect DNA and RNA from enzymatic degradation by encapsulation and stability in exosomes. The enhanced stability and retention of exosomes in liquid biopsies increases the availability and performance of exosomes as cancer biomarkers.258 Cancer cells contain cargo molecules, such as nucleic acid, proteins, metabolites, and lipids that are relatively different from normal cells, which is a contributing factor for their candidacy as cancer biomarkers. Exosomes isolated and purified from patient plasma samples enriched for miR-10b-5p, miR-101-3p, and miR-143-5p have been identified as potential diagnostic markers for gastric cancer with lymph node metastasis, gastric cancer with ovarian metastasis, and gastric cancer with liver metastasis, respectively.259 Kato et al analyzed the expression of CD44 protein and mRNA from cell lysates and exosomes from prostate cancer cells.260 Exosomes from serum containing CD44v8-10 mRNA was used as a diagnostic marker for docetaxel resistance in prostate cancer patients. The study was performed to evaluate plasma exosomal mRNA-125a-5p and miR-141-5p miRNAs as biomarkers for the diagnosis of prostate cancer from 19 healthy individuals and 31 prostate cancer patients. In comparing the miR-125a-5p/miR-141-5p level ratio, prostate cancer patients had significantly higher levels of miR-125a-5p/miR-141-5p. The findings from this study demonstrated that plasma exosomal expression of miR-141-3p and miR-125a-5p are markers of specific tumor traits associated with prostate cancer.261 Serum samples from 81 patients with gastric cancer showed that exosomes contained significant levels of long non-coding RNA (lncRNA) H19, which could be a diagnostic marker for gastric cancer.262 Plasma exosomes are suitable candidates as biomarkers for various diseases. For instance, plasma exosome lncRNA expression profiles were examined in esophageal squamous cell carcinoma (ESCC) patients. The findings suggest that five different types of lncRNAs were at significantly higher levels in exosomes from ESCC patients than in non-cancer controls. These lncRNAs may serve as highly effective, noninvasive biomarkers for ESCC diagnosis.263 Differential expression of lncRNAs, such as LINC00462, HOTAIR, and MALAT1, are significantly upregulated in hepatocellular carcinoma (HCC) tissues. The exosomes of the control group had a larger number of lncRNAs with a high amount of alternative splicing compared to hepatic disease patients.264 To demonstrate exosomes as a non-invasive cancer diagnostic tool, RNA-sequencing analysis was performed between three pairs of non-small-cell lung cancer (NSCLC) patients and controls from Chinese populations. The results show that circ_0047921, circ_0056285, and circ_0007761 were significantly expressed and that these exosomal circRNAs are promising biomarkers for NSCLC diagnosis.265 Exosomes were isolated from the serum of 34 patients with acute myocardial infarction (AMI), 31 patients with unstable angina (UA), and 22 healthy controls. The isolated exosomes exhibited higher levels of miR-126 and miR-21 in the patients with UA and AMI than in the healthy controls.266 Xu et al designed a study to examine tumor-derived exosomes as diagnostic biomarkers. In this study exosome miRNA microarray analysis was performed in the peripheral blood from four lung adenocarcinoma patients, including two with metastasis and two without metastasis. The results found that miR-4436a and miR-4687-5p were upregulated in the metastasis and non-metastasis group, while miR-22-3p, miR-3666, miR-4448, miR-4449, miR-6751-5p, and miR-92a-3p were downregulated. Exosomes containing miR-4448 have served as a diagnostic marker of patients with adenocarcinoma metastasis. Increased understanding of exosome biogenesis, structure, and function would enhance the performance of biomarkers in various kinds of disease diagnosis, prognosis, and surveillance.267

Exosomes have unique features such as ease of handling, molecular composition, and critical immunogenicity, and it is particularly easy to use them to transfer genes and proteins into cells. These unique characteristic features can inhibit angiogenesis and cancer metastasis, which are the two main targets of cancer therapy.268,269 Exosomes have potential therapeutic applications in a variety of diseases due to their potential capacity as vehicles for the delivery of therapeutic agents (Figure 5). Exosomes from colon cancer cells contain the highly immunogenic antigens MelanA/Mart-1 and gp100, serving as an indicator of tumor origin in particular organelles. Animal studies have demonstrated that tumor-derived antigen-containing exosomes induce potent antitumor T-cell responses and tumor regression.270 Exosomes containing tumor antigens are able to stimulate CD4+and CD8+T cells, and antigen-presenting exosomes inhibit tumor growth.135,271,272 MSC-derived exosomes exhibit the immunomodulatory and cytoprotective activities of their parent cells.273,274 Similarly, exosomes derived from bone marrow show protective roles in myocardial ischemia/reperfusion injury,109 hypoxia-induced pulmonary hypertension,275 and brain injury,276,277 and inhibit breast cancer growth via vascular endothelial growth factor down-regulation and miR-16 transfer in mice.278 Mesenchymal cell- and epithelial cell-derived exosomes exhibit tolerance and without any undesired side effects in patients and also act as therapeutic agents themselves.48,279 Exosomes engineered with ligands containing RGD peptide are used to induce signaling in specific cell types, and doxorubicin-loaded exosomes derived from dendritic cells show therapeutic responses in mammary tumor-bearing mice.46 Exosomal microRNAs are able to control other cells, and the delivery of miRNA or siRNA payload promotes anticancer activity in mammary carcinoma and glioma.280,281 Rabies virus glycoprotein (RVG)-modified dendritic cell-derived exosomes suppress the expression of BACE1 in the brain, which indicates the therapeutic potential of exosomes to target AD.282 Furthermore, these exosomes stimulated neurite outgrowth in cultured astrocytes by transferring miR-133b between cells.27 Immunotherapy is able to induce tumor-targeting immunity or an antitumor host immune response. For example, tumor-associated antigen-loaded mature autologous dendritic cells increase survival of metastatic castration-resistant patients.283 Exosome therapy induces upregulation of CD122 molecules in CD4+ T cells, whereas the lymphocyte pool is stable. Multiple vaccinations with exosomes increase circulating CD3-/CD56+ natural killer (NK) cells.284 An in vitro study demonstrated that adipose stem cell-derived exosomes up-regulate the peroxisome proliferator-activated receptor gamma coactivator 1, phosphorylate the cyclic AMP response element binding protein, and ameliorate abnormal apoptotic protein levels.285 Exosomes are used as potential carriers to carry anti-inflammatory drugs. Curcumin-encapsulated exosomes show significant anti-inflammatory activity, and exosomes are also used to deliver anti-inflammatory drugs to the brain through a noninvasive intranasal route.286,287 Turturici et al reported that specific progenitor cell-derived EVs contain biological cargo that promotes angiogenesis and tissue repair, and modulates immune functions.288

Figure 5 Therapeutic potential and versatile clinical implications of exosomes.

Generally, exosomes serve as vehicles for the delivery of drugs and are also actively involved as therapeutic agents. Conversely, injected exosomes enter into other cells and deliver functional cargo molecules very efficiently and rapidly, with minimal immune clearance and are well tolerated.16,21,245,289,290 Intravenous administration of human MSC-derived exosomes supports neuroprotection in a swine model of traumatic brain injury.291 In vitro and in vivo models demonstrate that exosomes from human-induced pluripotent stem cell-derived mesenchymal stromal Cells (hiPSC-MSCs) protect the liver against hepatic ischemia/reperfusion injury through increasing the level of proliferation of primary hepatocytes, activity of sphingosine kinase, and synthesis of sphingosine-1-phosphate (S1P).292 Exosomes derived from macrophages show potential for use in neurological diseases because of their easy entry into the brain by crossing the blood-brain barrier (BBB). Catalase-loaded exosomes displayed a neuroprotective effect in a mouse model of PD and exosomes loaded with dopamine entered into the brain better in comparison to free dopamine.33,293 Treatment of tumor-bearing mice with autologous exosomes loaded with gemcitabine significantly suppressed tumor growth and increase longevity, and caused only minimal damage to normal tissues. The study demonstrated that autologous exosomes are safe and effective vehicles for targeted delivery of GEM against pancreatic cancer.294

Generally, lipid-based nanoparticles such as liposomes or micelles, or synthetic delivery systems have been adopted to transport active molecules. However, the merits of synthetic systems are limited due to various factors including inefficiency, cytotoxicity and/or immunogenicity. Therefore, the development of natural carrier systems is indispensable. One of the most prominent examples of such natural carriers are exosomes, which are used to transport drug and active biomolecules. Exosomes are more compatible with other cells because they carry various targeting molecules from their cells of origin. Exosomes are nano-sized membrane vesicles derived from almost all cell types, which carry a variety of cargo molecules from their parent cells to other cells. Due to their natural biogenesis and unique qualities, including high biocompatibility, enhanced stability, and limited immunogenicity, they have advantages as drug delivery systems (DDSs) compared to traditional synthetic delivery vehicles. For instance, extracellular vesicles, including exosomes, carry and protect a wide array of nucleic acids and can potentially deliver these into recipient cells.6 EVs possess inherent targeting properties due to their lipid composition and protein content enabling them to cross biological barriers, and these salient features exploit endogenous intracellular trafficking mechanisms and trigger a response upon uptake by recipient cells.45,295297 The lipid composition and protein content of exocytic vesicles have specific tropism to specific organs.296 The integrin of exosomes determines the ability to alter the pharmacokinetics of EVs and increase their accumulation in various type of organs including brain, lungs, or liver.117 For example, EVs containing Tspan8 in complex with integrin alpha4 were shown to be preferentially taken up by pancreatic cells.298 Similarly, the lipid composition of EVs influences the cellular uptake of EVs by macrophages.299 EVs derived from dendritic cell achieved targeted knockdown by fusion between expression of Lamp2b and neuron-specific RVG peptide by using siRNA in neuronal cell.45 EVs loaded with Cre recombinase protein were able to deliver functional CreFRB to recipient cells through active and passive mechanisms in the presence of endosomal escape, enhancing the compounds chloroquine and UNC10217832A.300 EVs from cardiosphere-derived cells achieved targeted delivery by fusion of the N-terminus of Lamp2b to a cardiomyocyte-specific peptide (CMP).301 RVG-exosomes were used to deliver anti-alpha-synuclein shRNA minicircle (shRNA-MC) therapy to the alpha-synuclein preformed-fibril-induced mouse model of parkinsonism. This therapy decreased alpha-synuclein aggregation, reduced the loss of dopaminergic neurons, and improved clinical symptoms. RVG exosome-mediated therapy prolonged the effectiveness and was specifically delivered into the brain.302 Zhang et al evaluated the effects of umbilical cord-derived macrophage exosomes loaded with cisplatin on the growth and drug resistance of ovarian cancer cells. High loading efficiency of cisplatin was achieved by membrane disruption of exosomes by sonication.303 Incorporation of cisplatin into umbilical cord blood-derived M1 macrophage exosomes increased cytotoxicity 3.3-fold in drug-resistant A2780/DDP cells and 1.4-fold in drug-sensitive A2780 cells, compared to chemotherapy alone. Loading of cisplatin into M2 exosomes increased cytotoxicity by nearly 1.7-fold in drug-resistant A2780/DDP cells and 1.4-fold in drug-sensitive A2780 cells. The findings suggest that cisplatin-loaded M1 exosomes are potentially powerful tools for the delivery of chemotherapeutics to treat cancers regardless of drug resistance. Shandilya et al developed a chemical-free and non-mechanical method for the encapsulation and intercellular delivery of siRNA using milk-derived exosomes through conjugation between bovine lactoferrin with poly-L-lysine, wherein lactoferrin as a ligand was captured by the GAPDH present in exosomes, loading siRNA in an effortless manner.304 Targeted drug delivery was achieved with low immunogenicity and toxicity using exosomes derived from immature dendritic cells (imDCs) from BALB/c mice by expressing the fusion protein RGD. Recombinant methioninase (rMETase) was loaded into tumor-targeting iRGD-Exos. The findings suggest that the iRGD-Exos-rMETase group exhibited significant antitumor activity compared to the rMETase group.305 Several diseases show high inflammatory responses; therefore, amelioration of inflammatory responses is a critical factor. The inflammatory responses in various disease models can be attenuated through introduction of super-repressor IB (srIB), which is the dominant active form of IB, and can inhibit translocation of nuclear factor B into the nucleus. Intraperitoneal injection of purified srIB-loaded exosomes (Exo-srIBs) showed diminished mortality and systemic inflammation in septic mouse models.306 Systemic administration of macrophage-derived exosomes modified with azide and conjugated with dibenzocyclooctyne-modified antibodies of CD47 and SIRP (aCD47 and aSIRP) through pH-sensitive linkers can actively and specifically target tumors through distinguishing between aCD47 and CD47 on the tumor cell surface.307 SPION-decorated exosomes prepared using fusion proteins of cell-penetrating peptides (CPP) and TNF- (CTNF-)-anchored exosomes coupled with superparamagnetic iron oxide nanoparticles (CTNF--exosome-SPIONs) significantly enhanced tumor cell growth inhibition via induction of the TNFR I-mediated apoptotic pathway. Furthermore, in vivo studies in murine melanoma subcutaneous cancer models showed that TNF--loaded exosome-based vehicle delivery enhanced cancer targeting under an external magnetic field and suppressed tumor growth with mitigating toxicity.308 Yu et al309 developed a formulation of erastin-loaded exosomes labeled with folate (FA) to form FA-vectorized exosomes loaded with erastin (erastin@FA-exo) to target triple-negative breast cancer (TNBC) cells with overexpression of FA receptors. Erastin@FA-exo increased the uptake efficiency of erastin and also significantly inhibited the proliferation and migration of MDA-MB-231 cells compared with erastin@exo and free erastin. Interestingly, erastin@FA-exo promoted ferroptosis with intracellular depletion of glutathione and ROS generation. Plasma exosomes (Exo) loaded with quercetin (Exo-Que) improved the drug bioavailability, enhanced the brain targeting of Que and potently ameliorated cognitive dysfunction in okadaic acid (OA)-induced AD mice compared to free quercetin by inhibiting phosphorylated tau-mediated neurofibrillary tangles.310 Spinal cord injury (SCI) causes paralysis of the limbs. To determine the role of resveratrol in SCI, exosomes derived from resveratrol-treated primary microglia were used as carriers which are able to enhance the solubility of resveratrol and enhance penetration of the drug through the BBB, thereby increasing its concentration in the CNS. The findings demonstrated that Exo + Res are highly effective at crossing the BBB with good stability, suggesting they have potential for enhancing targeted drug delivery and recovering neuronal function in SCI therapy, and is likely associated with the induction of autophagy and inhibition of apoptosis via the PI3K signaling pathway.311 Delivery of miR-204-5p by exosomes inhibits cancer cell proliferation and tumor growth, and induces apoptosis and chemoresistance by specifically suppressing the target genes of miR-204-5p in human cancer cells.312 Engineered exosomes with RVG peptide on the surface for neuron targeting and NGF-loaded exosomes (NGF@ExoRVG) were efficiently delivered into ischemic cortex, with a burst release of encapsulated NGF protein and de novo NGF protein translated from the delivered mRNA. The delivered NGF protein showed high stability and a long retention time, and also reduced inflammation by reshaping microglia polarization, promoted cell survival, and increased the population of double cortin-positive cells, a neuroblast marker.313 Intranasal delivery of mesenchymal stem cell-derived extracellular vesicles exerts immunomodulatory and neuroprotective effects in a 3xTg model of AD by activation of microglia cells and increased dendritic spine density.314 Exosome-encapsulated paclitaxel showed efficacy in the treatment of multi-drug resistant cancer cells and it overcomes MDR in cancer cells.315,316 Saari et al found that the loading of Paclitaxel to autologous prostate cancer cell-derived EVs increased its cytotoxic effect.316 Exosome loaded doxorubicin (exoDOX) avoids undesired and unnecessary heart toxicity by partially limiting the crossing of DOX through the myocardial endothelial cells.317 Studies from in vitro and in vivo demonstrate that exosome loaded doxorubicin showed that exosomes did not decrease the efficacy of DOX and there is no cardiotoxicity in DOX-treated mice.318

The intrinsic properties of exosomes have been exploited to control various types of diseases, including neurodegenerative conditions and cancer, through promoting or restraining the delivery of proteins, metabolites, and nucleic acids into recipient cells effectively, eventually altering their biological response. Furthermore, exosomes can be engineered to deliver diverse therapeutic payloads to the target site, including siRNAs, antisense oligonucleotides, chemotherapeutic agents, and immune modulators. The natural lipid and protein composition of exosomes increases bioavailability and minimizes undesirable side effects to the recipients. Due to the availability of exosomes in biological fluid, they can be easily used as potential biomarkers for diagnosis of diseases. Exosomes are naturally decorated with numerous ligands on the surface that can be beneficial for preferential tumor targeting.282 Due to their unique properties, including superior targeting capabilities and safety profile, exosomes are the subject of clinical trials as cancer therapeutic agents.284 Exosomes derived from DCs loaded with tumor antigens have been used to vaccinate cancer patients with the goal of enhancing anti-tumor immune responses.284,319,320

Due to the potential level of various types of cargoes and salient features, exosomes are involved in intercellular messaging and disease diagnosis. As a result of dedicated studies, exosomes have been identified as natural drug delivery vehicles. However, we still face challenges regarding the purity of exosomes due to the lack of standardized techniques for their isolation and purification, inefficient separation methods, difficulties in characterization, and lack of specific biomarkers.321 The first challenge is the use of conventional methods, which are laborious for isolation and purification, time consuming, and vulnerable to contamination by other impurities, which will affect drug delivery processes. The second challenge is the various cellular origins of exosomes, which could affect specific applications. For example, in the application of exosomes in cancer therapy, we should avoid the use of exosomes derived from cancer cells, due to their oncogenic properties. Finally, exosomes have variable properties due to extraction from different types of cell and different cell culture techniques. Therefore, there is a necessity to address and overcome the challenges. There is also a need for an exosome consortium to develop common protocols for the development of rapid and precise methods of exosome isolation, and to assist the selection of sources that are dependent upon the specific therapeutic application. The most important challenge of exosome biology is the clinical translation of exosome-based research using different cell sources. Further characterization studies based on therapeutic applications are needed. Finally, important steps need to be taken to purify exosomes in a feasible, rapid, cost-effective, and scalable manner, which are free from downstream processing and have minimal processing times, that are specifically targeted to therapeutic applications and clinical settings.

The achievement of exosome therapy is based on success rate of clinical trials. Exosomes with size ranges from 60 to 200nm have been used as an active pharmaceutical ingredient or drug carrier in disease treatment. Exosomes derived from human and plant-derived exosomes are registered in clinical trials, but more complete reports are available for humanderived exosomes.322 There are two major exosomes from DCs and MSCs are frequently used in clinical trials, which potentially induce inflammation response and inflammation treatment. The more crucial aspect of exosomes in clinical trials needs to comply with good manufacturing practice (GMP) including upstream, downstream and quality control. Recently, France and USA conducted clinical trials using EVs containing MHCpeptide complexes derived from dendritic could alter tumor growth in immune competent mice and a Phase I anti-non-small cell lung cancer319,320 and several other clinical trial studies are shown in Table 1. Recent clinical case shows promising results with MSC-EVs derived from unrelated bone marrow donors for the treatment of a steroid-refractory graft-vs-host disease patient.279 Similarly, exosomes were used for the treatment of various types of diseases such as melanoma, non-small-cell-lung cancer, colon cancer and chronic kidney disease.284,319,320,323,324

Table 1 Summary of the Exosome Used in Clinical Trials (Source: clinicaltrials.com)

Exosomes are nano-sized membrane vesicles released by the fusion of an organelle of the endocytic pathway, a multivesicular body, with the plasma membrane. Since the last decade, exosomes have played a critical role in nanomedicine and studies related to exosome biology have increased immensely. Exosomes are secreted by almost all cell types and they are found in almost all types of body fluids. They function as mediators of cell-cell communications and play a significant role in both physiological and pathological processes. Exosomes carry a wide range of cargoes including proteins, lipids, RNAs, and DNA, which mediate signaling to recipient cells or tissues, making them a promising diagnostic biomarker and therapeutic tool for the treatment of cancers and other pathologies. In this review, we summarized what is known to date about the factors involved in exosome biogenesis and the role of exosomes in intercellular signaling and cell-cell communications, immune responses, cellular homeostasis, autophagy, and infectious diseases. Further, we reviewed the role of exosomes as diagnostic markers, and their therapeutic and clinical implications. Furthermore, we highlighted the challenges and outstanding developments in exosome research. The clinical application of exosomes is inevitable and they represent multicomponent biomarkers for several diseases including cancer and neurological diseases, etc. Recently, the mortality rate due to various types of cancers has increased. Therefore, therapies are essential to reduce mortality rates. At this juncture, we need sensitive, rapid, cost-effective, and large-scale production of exosomes to use as cancer biomarkers in diagnosis, prognosis, and surveillance. Furthermore, novel technologies are required for further tailoring exosomes as drug delivery vesicles with high drug pay loads, high specificity and low immunogenicity, and free of toxicity undesired side-effects. In addition, standardized and uniform protocols are necessary to isolate and purify exosomes for clinical applications, and more precise isolation and characterization procedures are required to increase understanding of the heterogeneity of exosomes, their cargo, and functions. There is an urgent need for information regarding the composition and mechanisms of action of the various substances in exosomes and to determine how to obtain highly purified exosomes at the right dosage for their clinical use. Currently, exosomes represent a promising tool in the field of nanomedicine and may provide solutions to a variety of todays medical mysteries.

The future direction of exosome research must focus on addressing the differential responses of communication between normal cells and cancer cells, how normal cells rapidly become cancerous, and how exosomes plays critical role in cancer progression via cell-cell communications. In vivo studies need to urgently address the critical factors such as biogenesis, trafficking, and cellular entry of exosomes originating from unmanipulated exosomes that control regulatory pathological functions. Further studies are required to decipher the mechanism of the cell-specific secretion and transport of exosomes, and the biological controls exerted by target cells. Exosomes represent a clinically significant nanoplatform. To substantiate this idea, numerous systematic in vivo studies are necessary to demonstrate the potency and toxicology of exosomes, which could help bring this novel idea a step closer to clinical reality. The most vital part of the system is to optimize the conditions for the engineering of exosomes that are non-toxic, for use in clinical trials. Furthermore, the translation of exosomes into clinical therapies requires their categorization as active drug components or drug delivery vehicles. Finally, future research should focus on the nanoengineering of exosomes that are tailored specifically for drug delivery and clinical efficacy.

Although we are the authors of this review, we would never have been able to complete it without the great many people who have contributed to the field of exosomes biogenesis, functions, therapeutic and clinical implications of exosomes aspects. We owe our gratitude to all those researchers who have made this review possible. We have cited as many references as permitted and apologize to the authors of those publications that we have not cited due to the limitation of references. We apologize to other authors who have worked on these aspects but whom we have unintentionally overlooked.

This study was supported by the KU-Research Professor Program of Konkuk University.

This work was supported by a grant from the Science Research Center (2015R1A5A1009701) of the National Research Foundation of Korea.

The authors report no conflicts of interest related to this work..

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[Full text] A Comprehensive Review on Factors Influences Biogenesis, Functions, Th | IJN - Dove Medical Press

Cardiac Stem Cells Comments Off on [Full text] A Comprehensive Review on Factors Influences Biogenesis, Functions, Th | IJN – Dove Medical Press | February 17th, 2021

Feb. 16, 2021 12:00 UTC

CAMBRIDGE, Mass.--(BUSINESS WIRE)-- bluebird bio, Inc. (Nasdaq: BLUE) announced today that the company has placed its Phase 1/2 (HGB-206) and Phase 3 (HGB-210) studies of LentiGlobin gene therapy for sickle cell disease (SCD) (bb1111) on a temporary suspension due to a reported Suspected Unexpected Serious Adverse Reaction (SUSAR) of acute myeloid leukemia (AML).

In line with the clinical study protocols for HGB-206 and HGB-210, bluebird bio placed the studies on temporary suspension following a report received last week that a patient who was treated more than five years ago in Group A of HGB-206 was diagnosed with AML. The company is investigating the cause of this patients AML in order to determine if there is any relationship to the use of BB305 lentiviral vector in the manufacture of LentiGlobin gene therapy for SCD. In addition, a second SUSAR of myelodysplastic syndrome (MDS) in a patient from Group C of HGB-206 was reported last week to the company and is currently being investigated.

No cases of hematologic malignancy have been reported in any patient who has received treatment with betibeglogene autotemcel for transfusion-dependent -thalassemia (licensed as ZYNTEGLOTM in the European Union and the United Kingdom), however because it is also manufactured using the same BB305 lentiviral vector used in LentiGlobin gene therapy for SCD, the company has decided to temporarily suspend marketing of ZYNTEGLO while the AML case is assessed.

The safety of every patient who has participated in our studies or is treated with our gene therapies is the utmost priority for us, said Nick Leschly, chief bluebird. We are committed to fully assessing these cases in partnership with the healthcare providers supporting our clinical studies and appropriate regulatory agencies. Our thoughts are with these patients and their families during this time.

The independent safety review board monitoring the companys studies as well as the U.S. Food and Drug Administration (FDA) and European Medicines Agency (EMA) have been advised of these cases and bluebird bio will continue to work with regulatory agencies to complete its investigation.

Investor Conference Call Information

bluebird bio will hold a conference call to discuss this update on Tuesday, February 16 at 8:00 a.m. ET. Investors may listen to the call by dialing (844) 825-4408 from locations in the United States or +1 (315) 625-3227 from outside the United States. Please refer to conference ID number 880-6406.

To access the live webcast of bluebird bios presentation, please visit the Events & Presentations page within the Investors & Media section of the bluebird bio website at http://investor.bluebirdbio.com. A replay of the webcast will be available on the bluebird bio website for 90 days following the event.

About HGB-206 and HGB-210

HGB-206 is an ongoing, Phase 1/2 open-label study designed to evaluate the efficacy and safety of LentiGlobin gene therapy for sickle cell disease (SCD) that includes three treatment cohorts: Groups A, B and C. A refined manufacturing process designed to increase vector copy number (VCN) and further protocol refinements made to improve engraftment potential of gene-modified stem cells were used for Group C. Group C patients also received LentiGlobin for SCD made from HSCs collected from peripheral blood after mobilization with plerixafor, rather than via bone marrow harvest, which was used in Groups A and B of HGB-206.

HGB-210 is an ongoing Phase 3 single-arm open-label study designed to evaluate the efficacy and safety of LentiGlobin gene therapy for SCD in patients between two years and 50 years of age with sickle cell disease.

About LentiGlobin for SCD (bb1111)

LentiGlobin gene therapy for sickle cell disease (bb1111) is an investigational treatment being studied as a potential treatment for SCD. bluebird bios clinical development program for LentiGlobin for SCD includes the completed Phase 1/2 HGB-205 study, the ongoing Phase 1/2 HGB-206 study, and the ongoing Phase 3 HGB-210 study.

The U.S. Food and Drug Administration granted orphan drug designation, fast track designation, regenerative medicine advanced therapy (RMAT) designation and rare pediatric disease designation for LentiGlobin for SCD.

LentiGlobin for SCD received orphan medicinal product designation from the European Commission for the treatment of SCD, and Priority Medicines (PRIME) eligibility by the European Medicines Agency (EMA) in September 2020.

bluebird bio is conducting a long-term safety and efficacy follow-up study (LTF-307) for people who have participated in bluebird bio-sponsored clinical studies of LentiGlobin for SCD. For more information visit: https://www.bluebirdbio.com/our-science/clinical-trials or clinicaltrials.gov and use identifier NCT04628585 for LTF-307.

LentiGlobin for SCD is investigational and has not been approved in any geography.

About ZYNTEGLO (betibeglogene autotemcel)

Betibeglogene autotemcel (beti-cel) is a one-time gene therapy that adds functional copies of a modified form of the -globin gene (A-T87Q-globin gene) into a patients own hematopoietic (blood) stem cells (HSCs). Once a patient has the A-T87Q-globin gene, they have the potential to produce HbAT87Q, which is gene therapy-derived adult Hb, at levels that may eliminate or significantly reduce the need for transfusions. In studies of beti-cel, transfusion independence (TI) is defined as no longer needing red blood cell transfusions for at least 12 months while maintaining a weighted average Hb of at least 9 g/dL.

The European Commission granted conditional marketing authorization (CMA) for beti-cel, marketed as ZYNTEGLO gene therapy, for patients 12 years and older with transfusion-dependent -thalassemia (TDT) who do not have a 0/0 genotype, for whom hematopoietic stem cell (HSC) transplantation is appropriate, but a human leukocyte antigen (HLA)-matched related HSC donor is not available.

Non-serious adverse events (AEs) observed during clinical studies that were attributed to beti-cel included abdominal pain, thrombocytopenia, leukopenia, neutropenia, hot flush, dyspnea, pain in extremity, tachycardia and non-cardiac chest pain. One serious adverse event (SAE) of thrombocytopenia was considered possibly related to beti-cel.

Additional AEs observed in clinical studies were consistent with the known side effects of HSC collection and bone marrow ablation with busulfan, including SAEs of veno-occlusive disease.

For details, please see the Summary of Product Characteristics (SmPC).

On April 28, 2020, the European Medicines Agency (EMA) renewed the CMA for beti-cel. The CMA for beti-cel is valid in the 27 member states of the EU as well as the UK, Iceland, Liechtenstein and Norway.

The U.S. Food and Drug Administration granted beti-cel Orphan Drug status and Breakthrough Therapy designation for the treatment of TDT. Beti-cel is not approved in the U.S. Beti-cel continues to be evaluated in the ongoing Phase 3 Northstar-2 (HGB-207) and Northstar-3 (HGB-212) studies.

bluebird bio is conducting a long-term safety and efficacy follow-up study, LTF-303 for people who have participated in bluebird bio-sponsored clinical studies of ZYNTEGLO.

About bluebird bio, Inc.

bluebird bio is pioneering gene therapy with purpose. From our Cambridge, Mass., headquarters, were developing gene and cell therapies for severe genetic diseases and cancer, with the goal that people facing potentially fatal conditions with limited treatment options can live their lives fully. Beyond our labs, were working to positively disrupt the healthcare system to create access, transparency and education so that gene therapy can become available to all those who can benefit.

bluebird bio is a human company powered by human stories. Were putting our care and expertise to work across a spectrum of disorders: cerebral adrenoleukodystrophy, sickle cell disease, -thalassemia and multiple myeloma, using gene and cell therapy technologies including gene addition, and (megaTAL-enabled) gene editing.

bluebird bio has additional nests in Seattle, Wash.; Durham, N.C.; and Zug, Switzerland. For more information, visit bluebirdbio.com.

Follow bluebird bio on social media: @bluebirdbio, LinkedIn, Instagram and YouTube.

ZYNTEGLO, betibeglogene autotemcel, beti-cel, and bluebird bio are trademarks of bluebird bio, Inc.

Forward-Looking Statements

This release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995, including statements regarding the Companys timing and expectations regarding its investigation of the relationship of the AML and MDS events to the use of lentiviral vector BB305 in LentiGlobin gene therapy for SCD, and any myeloablation regimen used in connection with treatment. Any forward-looking statements are based on managements current expectations of future events and are subject to a number of risks and uncertainties that could cause actual results to differ materially and adversely from those set forth in or implied by such forward-looking statements, many of which are beyond the Companys control. These risks and uncertainties include, but are not limited to: the risk that the Company may not be able to definitively determine whether the lentiviral vector BB305 used in LentiGlobin gene therapy for SCD and in betibeglogene autotemcel is related to the patients AML in a timely manner, or at all; the risk that the lentiviral vector BB305 has caused insertional oncogenic events, including AML; the risk that insertional oncogenic events associated with lentiviral vector or additional MDS events associated with myeloablation will be discovered or reported over time; the risk that regulatory authorities may impose a clinical hold, in addition to our temporary clinical hold on the HGB-206 and HGB-210 studies, or on additional programs; the risk that we may not be able to address regulatory authorities concerns quickly or at all; the risk that we may not resume patient treatment with ZYNTEGLO in the commercial context in a timely manner or at all; the risk that our lentiviral vector platform across our severe genetic disease programs may be implicated, affecting the development and potential approval of elivaldogene autotemcel; the risk that we may not be able to execute on our business plans, including our commercialization plans, meeting our expected or planned regulatory milestones, submissions, and timelines, research and clinical development plans, and in bringing our product candidates to market; and the risk that with the impact on the execution and timing of our business plans, we may not successfully execute our previously announced plans to spin off our oncology programs into an independent publicly-traded entity. For a discussion of other risks and uncertainties, and other important factors, any of which could cause our actual results to differ from those contained in the forward-looking statements, see the section entitled Risk Factors in our most recent Form 10-Q, as well as discussions of potential risks, uncertainties, and other important factors in our subsequent filings with the Securities and Exchange Commission. All information in this press release is as of the date of the release, and bluebird bio undertakes no duty to update this information unless required by law.

View source version on businesswire.com: https://www.businesswire.com/news/home/20210216005442/en/

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bluebird bio Announces Temporary Suspension on Phase 1/2 and Phase 3 Studies of LentiGlobin Gene Therapy for Sickle Cell Disease (bb1111) - BioSpace

Cardiac Stem Cells Comments Off on bluebird bio Announces Temporary Suspension on Phase 1/2 and Phase 3 Studies of LentiGlobin Gene Therapy for Sickle Cell Disease (bb1111) – BioSpace | February 17th, 2021

Betibeglogene autotemcel (beti-cel), a one-time gene therapy, enabled durable transfusion independence in most patients with transfusion-dependent -thalassemia (TDT) who were treated across 4 clinical studies.

Of 60 patients enrolled overall, 17 of 22 (77%) treated in the 2 phase 1/2 studies were able to stop packed red blood cell transfusions. In the 2 phase 3 studies, which used a refined manufacturing process resulting in improved beti-cel characteristics, 89% (n = 31/35) of patients with at least 6 months of follow-up achieved transfusion independence for more than 6 months,1 reported Suradej Hongeng, MD, during the virtual 2021 Transplantation & Cellular Therapy Meetings.

The median follow-up after beti-cel infusion in the 4 studies has been 24.8 months (range, 1.1-71.8).

With up to 6 years of follow-up, 1-time beti-cel gene therapy enabled durable transfusion independence in the majority of patients, said Hongeng, from Ramathibodi Hospital of Mahidol University, in Bangkok, Thailand.

Patients who achieved transfusion independence experienced a 38% median reduction in liver iron concentration (LIC) from baseline to month 48. The median reduction in LIC was 59% in patients with a baseline LIC more than 15 mg/g dw. A total of 21 of 37 (57%) patients who achieved transfusion independence have stopped iron chelation for 6 months or longer, with a median duration of 18.5 months from stopping iron chelation to last follow-up.

Erythropoiesis as determined by soluble transferrin receptor level was also improved in transfusion-independent patients. Bone marrow biopsies showed improvement in the myeloid:erythroid ratio.

Beti-cel adds functional copies of a modified form of the -globin (A-T87Q-globin) gene into a patients own hematopoietic stem cells (HSCs) through transduction of autologous CD34+ cells using a BB305 lentiviral vector. Following single-agent busulfan myeloablative conditioning, beti-cel is infused, after which the transduced HSCs engraft and reconstitute red blood cells containing functional adult hemoglobin derived from the gene therapy.

Of the 60 patients treated, 43 were genotype non-/ and 17 were / . The median age at consent was 20 years in the phase 1/2 trials and 15 years in the phase 3 trials. Median LIC at baseline was 7.1 and 5.5 mg Fe/g dw, respectively, and median cardiac T2 was 34 and 37 msec, respectively. The vector copy number was 0.8 in the phase 1/2 trial and 3.0 in the phase 3 study. Additionally, 32t and 78t CD34+ cells were transduced, respectively.

The phase 1/2 studies showed promising results but lower achievement of transfusion independence in patients with the / genotype, leading to a refinement in the manufacturing process, which resulted in a higher number of transduced cells and a higher number of vector copy number, said Hongeng.

The median time to neutrophil engraftment was 22.5 days and the median time to platelet engraftment was 44 days. Lymphocyte subsets were generally within the normal range after beti-cel infusion, which is different from allogeneic stem cell [transplantation], which is probably around 6 months to a year to get complete recovery of immune reconstitution, he said. The median duration of hospitalization was 42 days.

All patients were alive at the last follow-up (March 3, 2020). Eleven of 60 (18%) of patients experienced at least 1 adverse event (AE) considered related or possibly related to beti-cel, the most common being abdominal pain (8%) and thrombocytopenia (5%). Serious AEs were those expected after myeloablative conditioning: veno-occlusive liver disease (8%), neutropenia (5%), pyrexia (5%), thrombocytopenia (5%), and appendicitis, febrile neutropenia, major depression, and stomatitis (3% each).

Of the 7 patients experiencing veno-occlusive liver disease, 3 were of grade 4 and 2 were of grade 3. Two other patients had grade 2 veno-occlusive disease. There were no cases of insertional oncogenesis.

Persistent vector-positive hematopoietic cells and durable HbaT87Q levels supported stable total hemoglobin over time. In phase 3 trials, the median peripheral blood vector copy number was 1.2 c/dg at month 12 and 2.0 c/dg at month 24, and the median total hemoglobin was 11.5 g/dL at month 12 and 12.9 g/dL at month 24.

The weighted average of hemoglobin during transfusion independence in the phase 1/2 trials was 10.4 g/dL, and patients were transfusion-independent for a median of 51.2 months. In the phase 3 studies, the weighted average of hemoglobin during transfusion independence was 11.9 g/dL, and patients were transfusion-independent for a medium 17.7 months.

Hongeng S, Thompson AA, Kwiatkowski JL, et al. Efficacy and safety of betibeglogene autotemcel (beti-cel; LentiGlobin for -thalassemia) gene therapy in 60 patients with transfusion-dependent -thalassemia (TDT) followed for up to 6 years post-infusion. Presented at: 2021 Transplantation & Cellular Therapy Meetings; February 8-12, 2021; virtual. Abstract 1.

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Beti-Cel Gene Therapy Frees Patients With Beta-Thalassemia From Red Blood Cell Transfusions - OncLive

Cardiac Stem Cells Comments Off on Beti-Cel Gene Therapy Frees Patients With Beta-Thalassemia From Red Blood Cell Transfusions – OncLive | February 17th, 2021

New smart stem cells show a promising power to heal.

Researchers have reprogrammed human fat cells into adaptive smart stem cells that can lie dormant in the body until they are needed to heal various tissues. They demonstrated the cells' effectiveness at healing damaged tissue in a mouse study.

To create the smart stem cells, the team from UNSW Sydney exposed human fat cells to a compound mixture. After about three and a half weeks, the cells lost their original identity and began acting like stem cells, or iMS (induced multipotent stem cells).

"The stem cells acted like chameleons. They followed local cues to blend into the tissue that required healing."

"The stem cells we've developed can adapt to their surroundings and repair a range of damaged tissues," said UNSW hematologist John Pimanda, and co-author of the study, which they published in Science Advances.

"To my knowledge, no one has made an adaptive human multipotent stem cell before. This is uncharted territory."

Next, they injected the experimental iMS cells into healthy mice to see how the cells would respond. The cells remained dormant for some time, but they activated when the mouse was injured. Because of the cells' regenerative ability to act as "smart stem cells," they transformed themselves into whatever tissue was needed to heal the injured mouse --- like bone tissue, heart, or skin.

"The stem cells acted like chameleons," said Avani Yeola, lead author on the study at UNSW Medicine & Health. "They followed local cues to blend into the tissue that required healing."

All cells in a human body contain the same DNA. To differentiate between tissues, like a skin cell versus a bone cell, the cells only use a small portion of their total DNA. The rest of the DNA is shut down naturally by local modifications.

"The idea behind our approach was to reverse these modifications," said Pimanda. "We wanted the cells to have the option of using that part of the DNA if there was a signal from outside the cell."

Tissue-specific stem cells, like those that are restricted to becoming parts of the liver or lung, are limiting. But smart stem cells that can respond to their environment and become any tissue, like multipotent stem cells, will have many uses.

In the future, doctors could take a patient's fat cells, incubate them with the compound, and inject them into the patient to heal heart damage or trauma injuries.

But applications like this could be a long way off. The team needs to do much more research to prove this is safe in humans for different kinds of trauma before it becomes a real therapy.

We'd love to hear from you! If you have a comment about this article or if you have a tip for a future Freethink story, please email us at [emailprotected]

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Smart Stem Cells Made From Fat Have the Power to Heal - Freethink

Skin Stem Cells Comments Off on Smart Stem Cells Made From Fat Have the Power to Heal – Freethink | February 14th, 2021

Black patients in need of bone marrow or blood stem cell treatments have a decreased chance of matching with a donor. The Seattle branch hopes to change that.

Seattles Be The Match Collection Center opened up less than a year ago and is celebrating its 100th blood cell donation with an important message: More bone marrow donors of color are needed.

The nonprofit donation center is a part of the National Marrow Donor Program and increases the capacity to collect blood cells in the Pacific Northwest. Seattles Clinical Manager Hannah Erskine said this month is an important time to focus on the donation gap.

In the midst of Black History Month, its important to note that we frankly dont have enough Black and African American donors on the registry, said Erskin.

Only 4% of approximately 22 million donors on the registry are African American, lowering the chances that a Black patient can find a bone marrow donor who is a genetic match.

According to Be The Match data, the likelihood of finding a matched adult donor is only around 23% for an African American or Black patient, versus a 77% match rate for a white patient.

These matched bone marrow or blood stem cell transplants can help cure blood cancers like leukemia and lymphoma, as well as other blood conditions, such as sickle cell disease. Be The Match has coordinated more than 100,000 transplants.

Erskine said registering is a simple mouth swab that will be mailed to potential donors. They will be contacted if they are a match with a patient.

Being a matching blood stem cell donor can potentially save a life. The first step in changing the trend is to join the registry at http://www.bethematch.org.

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Be The Match encourages people of color to join bone marrow registry - KING5.com

Bone Marrow Stem Cells Comments Off on Be The Match encourages people of color to join bone marrow registry – KING5.com | February 14th, 2021

Leukemia is a type of cancer that affects the blood and bone marrow, where blood cells are formed. All types of leukemia cause rapid, uncontrolled growth of abnormal bone marrow and blood cells.

The main differences between the types include how fast the disease progresses and the types of cells it affects.

There are four main types of leukemia, which we describe in detail below:

Lymphocytic leukemia affects the lymphocytes, a type of white blood cell. Myeloid leukemia can affect the white blood cells, red blood cells, and platelets.

According to the National Cancer Institute, roughly 1.5% of people in the United States will receive a leukemia diagnosis at some point.

In this article, explore the four main types, their symptoms, the treatment options available, and the outlook.

The full name of this type of cancer is acute lymphocytic leukemia, and acute means that it grows quickly. Lymphocytic means that it forms in underdeveloped white blood cells called lymphocytes.

The disease starts in the bone marrow, which produces stem cells that develop into red and white blood cells and platelets.

In a healthy person, the bone marrow does not release these cells until they are fully developed. In someone with ALL, the bone marrow releases large quantities of underdeveloped white blood cells.

There are several subtypes of ALL, and the subtype may influence the best course of treatment and the prognosis.

One subtype is B-cell ALL. This begins in the B lymphocytes, and it is the most common form of ALL in children.

Another subtype is T-cell ALL. It can cause the thymus, a small organ at the front of the windpipe, to become enlarged, which can lead to breathing difficulties.

Overall, because ALL progresses quickly, swift medical intervention is key.

As research from 2020 acknowledges, healthcare providers still do not know what causes ALL. It may occur due to genetic factors or exposure to:

Although genetic factors may play a role, ALL is not a familial disease.

Learn more about ALL here.

ALL is the most common form of leukemia in children.

The risk of developing it is highest in children under 5 years old. The prevalence slowly rises again in adults over 50.

ALL symptoms can be nonspecific difficult to distinguish from those of other illnesses.

They may include:

In a person with AML, the bone marrow makes abnormal versions of platelets, red blood cells, and white blood cells called myeloblasts.

The full name of this disease is acute myeloid leukemia, and acute refers to the fact that it is fast-growing.

It forms in one of the following types of bone marrow cell:

Doctors classify AML by subtype, depending on:

AML can be difficult to treat and requires prompt medical attention.

Learn more about AML here.

The most common risk factor is myelodysplastic syndrome, a form of blood cancer that keeps the body from producing enough healthy blood cells.

Other factors that increase the risk of developing AML include:

Most people who develop AML are over 45. It is one of the most common types of leukemia in adults, though it is still rare, compared with other cancers.

It is also the second most common form of leukemia in children.

Symptoms of AML can vary and may include:

CLL is the most common form of leukemia among adults in the U.S. and other Western countries.

There are two types. One progresses slowly, and it causes the body to have high levels of characteristic lymphocytes, but only slightly low levels of healthy red blood cells, platelets, and neutrophils.

The other type progresses more quickly and causes a significant reduction in levels of all healthy blood cells.

In someone with CLL, the lymphocytes often look fully formed but are less able to fight infection than healthy white blood cells. The lymphocytes tend to build up very slowly, so a person might have CLL for a long time before experiencing symptoms.

Learn more about CLL here.

Genetic factors are the most likely cause. Others might include:

CLL is rare in children. It typically develops in adults aged 70 or over. However, it can affect people as young as 30.

CLL typically causes no early symptoms. When symptoms are present, they may include:

Also, 5090% of people with CLL have swollen lymph nodes.

CML is a slow-growing type of leukemia that develops in the bone marrow.

The full name of CML is chronic myeloid leukemia. As the American Cancer Society explain, a genetic change takes place in the early forms of the myeloid cells, and this eventually results in CML cells.

These leukemia cells then grow, divide, and enter the blood.

CML occurs due to a rearrangement of genetic material between the chromosomes 9 and 22.

This rearrangement fuses a part of the ABL1 gene from chromosome 9 with the BCR gene from chromosome 22, called the Philadelphia chromosome. The result of this fusion is called BCR-ABL1.

BCR-ABL1 produces a protein that promotes cell division and stops apoptosis, the process of cell death, which typically removes unneeded or damaged cells.

The cells keep dividing and do not self-destruct, resulting in an overproduction of abnormal cells and a lack of healthy blood cells.

This occurs during the persons lifetime and is not inherited.

CML typically affects adults. People aged 65 and older make up almost half of those who receive a CML diagnosis.

The symptoms of CML are unclear, but they may include:

The symptoms may vary, depending on the type of leukemia. Overall, a person should get in touch with a doctor if they experience:

Learn more about the symptoms of leukemia here.

Treatment for ALL typically involves three basic phases: induction, consolidation, and maintenance. We describe these in detail below.

Treatment for AML involves the first two phases. The induction phase may include treatment with the chemotherapy drugs cytarabine (Cytosar-U) and daunorubicin (Cerubidine) or idarubicin (Idamycin). The doctor may also recommend targeted drugs.

The goal of this phase is to kill the leukemia cells, causing the cancer to go into remission, using chemotherapy.

The doctor may recommend:

People having chemotherapy may need to see their doctors frequently and spend time in the hospital, due to the risk of serious infections and complications.

This phase of the treatment lasts for about 1 month.

Even if the treatment so far has led to remission, cancer cells may be hiding in the body, so more treatment is necessary.

The consolidation phase may involve taking high doses of chemotherapy. A doctor may also recommend targeted drugs or stem cell transplants.

This phase, consisting of ongoing chemotherapy treatments, usually lasts for 2 years.

Since CLL tends to progress slowly, and its treatment can have unpleasant side effects, some people with this condition go through a phase of watchful waiting before starting the treatment.

For a person with CML, the focus is often on providing the right treatment for the phase of the illness. To do this, a doctor considers how quickly the leukemia cells are building up and the extent of the symptoms. Stem cell transplants can be effective, but further treatment is necessary.

Overall, the initial treatment tends to include monoclonal antibodies, targeted drugs, and chemotherapy.

If the only concern is an enlarged spleen or swollen lymph nodes, the person may receive radiation or surgery.

If there are high numbers of CLL cells, the doctor may suggest leukapheresis, a treatment that lowers the persons blood count. This is only effective for a short time, but it allows the chemotherapy to start working.

For people with high-risk disease, doctors may recommend stem cell transplants.

A persons prognosis depends on the type of leukemia.

Learn more about survival rates for people with leukemia here.

About 8090% of adults with ALL experience complete remission for a while during treatment. And with treatment, most children recover from the disease.

Relapses are common in adults, so the overall cure rate is 40%. However, factors specific to each person play a role.

The older a person is when they receive an AML diagnosis, the more difficult it is to treat.

More than 25% of adults who achieve remission live for 3 years or more after treatment for AML.

A person may live for a long time with CLL.

Treatments can help keep the symptoms under control and prevent the disease from spreading. However, there is no cure.

Stem cell transplants can cure CML. However, this treatment is very invasive and is not suitable for most people with CML.

The United Kingdoms National Health Service estimate that 70% of males and 75% of females live for at least 5 years after receiving a CML diagnosis.

The earlier a person receives the diagnosis, the better their outlook.

Leukemia is a type of cancer that affects the blood and bone marrow. It can affect people of all ages.

There are four main types of leukemia. They differ based on how quickly they progress and the types of cells they affect.

Treatments for all types of leukemia continue to improve, helping people live longer and more fully with this condition.

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Types of leukemia: Prevalence, treatment options, and prognosis - Medical News Today

Bone Marrow Stem Cells Comments Off on Types of leukemia: Prevalence, treatment options, and prognosis – Medical News Today | February 14th, 2021

One-year-old Max Gardner was diagnosed with aplastic anaemia, in October 2020, a serious condition in which the bone marrow and stem cells do not produce enough blood cells.

After Max developed significant bruises and a rash over his body, parents, Connor Gardner and Rachel Nicholson, from Hebburn, were referred to South Tyneside District Hospital, where their brave little boy underwent tests.

Doctors initially believed that Max had an immune disorder but after he was admitted to the Royal Victoria Infirmary (RVI) further tests helped to diagnose him with aplastic anaemia.

The family was told that the condition could be fatal if not treated properly.

Doctors said Max needed to have a bone marrow transplant, which has the potential to cure him.

Dad Connor, 29, and mum Rachel, 27, were both tested to see if they would be a bone marrow match and the pair were overjoyed when Rachel was found to be a 9/10 match.

Max started chemotherapy on January 7 at the RVI and mum Rachel donated stem cells on January 13 at Newcastles Freeman Hospital.

The following day, January 14, Max underwent the transplant at the RVI.

The family is now waiting for the results of a Chimerism Test which will tell them for definite whether the stem cells have worked but signs are already looking positive.

Delighted dad, Connor, said: "His neutrophils [a type of white blood cell that protect us from infections] have been more than 0.50 for three days in a row, which means that he is essentially engrafted, which means that his body is accepting the transplant.

"So it is working, but we still have to wait for the test results."

Doctors say there is no doubt that it has worked with the way the numbers have gone up but they have to officially do it like that to make sure, Connor continued.

"But there is no reason why it shouldnt have [doctors] say.

"He has done really well to get to this stage, he has absolutely sailed through it, everyone is surprised with how well he has done.

This the best outcome we could have hoped for.

But it hasnt been plain sailing for the family, who have also had to face additional challenges during the treatment.

Parents Connor and Rachael initially were not allowed to visit Max at the same time due to Covid rules, however the hospital has now eased the restriction in their case.

The family also became sick with Norovirus in the run-up to the transplant, causing concern over whether it would have to be pushed back.

Thankfully, the transplant went ahead as planned and the family made a good recovery, although Max still needs help with his eating.

Max will now have to remain in hospital for a while longer as he recovers from the transplant.

Connor added: We can feel that we are nearly at the end of it.

"His neutrophils are the highest they have ever been since he became poorly so we feel like we are coming to the end.

The family are sharing Maxs journey to health on Instagram under the name @maxinamillionaajourney and hope his story will encourage people to sign up to the Anthony Nolan register to become a potential donor and help others like Max.

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Bone marrow transplant shows signs of curing brave little boy with one in a million condition - Shields Gazette

Bone Marrow Stem Cells Comments Off on Bone marrow transplant shows signs of curing brave little boy with one in a million condition – Shields Gazette | February 14th, 2021