hucMSC Exosome-Derived GPX1 Is Required for the Recovery of Hepatic Oxidant Injury

Exogenous exosomes from mice with acetaminophen-induced liver injury promote toxicity in the recipient hepatocytes and mice

Exosomes are small extracellular membrane vesicles released from endosomes of various cells and could be found in most body fluids. The main functions of exosomes have been recognized as important mediators of intercellular communication and as potential biomarkers of various disease states. This study investigated whether exogenous exosomes from mice with acetaminophen (APAP)-induced liver injury can damage the recipient hepatic cells or promote hepatotoxicity in mice. We observed that exogenous exosomes derived from APAP-exposed mice were internalized into the primary mouse hepatocytes or HepG2 hepatoma cells and significantly decreased the viability of these recipient cells. They also elevated mRNA transcripts and proteins associated with the cell death signaling pathways in primary hepatocytes or HepG2 cells via exosomes-to-cell communications. In addition, confocal microscopy of ex vivo liver section showed that exogenously added exosomes were accumulated in recipient hepatocytes. Furthermore, plasma reactive oxygen species and hepatic TNF-α/IL-1β production were elevated in APAP-exosomes recipient mice compared to control-exosomes recipient mice. The levels of apoptosis-related proteins such as phospho-JNK/JNK, Bax, and cleaved caspase-3 were increased in mouse liver received APAP-exosomes. These results demonstrate that exogenous exosomes from APAP-exposed mice with acute liver injury are functional and stimulate cell death or toxicity of the recipient hepatocytes and mice.

Exosomes in perspective: a potential surrogate for stem cell therapy

Exosomes as a unique subtype of small extracellular vesicles (sEVs) have attracted increasing interest in recent years in the fields of mesenchymal stromal cell (MSC) research. Studies have confirmed that exosomes derived from MSCs preserve immunosuppressive phenotype and can mimic therapeutic benefits of their parent cells. This review briefly summarizes most recent findings on the potential of exosomes as an alternative of therapeutic MSCs, focusing on the role of MSCs and their secreted exosomes in regulation of immune cells, preclinical and clinical evidence of therapeutic outcomes of MSC exosomes, and the biodistribution and pharmacokinetic profile of systemically administered exosomes. It is appreciated that exosomes from MSCs of different sources have variable contents including inflammatory mediators, tropic factors, signaling molecules, and nucleic acids (DNA, mRNA, microRNA and long non-coding RNA). Diverse functions of exosomes derived from different sources are expected. More importantly, exosomes isolated in vitro may not mirror that from in vivo, where donor MSCs are exposed to specific disease or injury-related conditions. Simulating in vivo microenvironment by pretreatment of MSCs with relevant chemical mediators may lead to their secretion of therapeutically more efficient exosomes/sEVs. However, we know very little about the key molecules involved and the differences between exosomes released under different conditions. These issues would be of tremendous interest to preclinical research that pursues exosome biology-underlain therapeutic mechanisms of MSCs. Further studies are expected to demonstrate the superiority of MSC-derived exsomes/sEVs as a pharmaceutical entity with regard to efficacy, safety, and practicability.

Extracellular vesicles: intelligent delivery strategies for therapeutic applications

Extracellular vesicles (EV), in particular exosomes, have been the object of intense research, due to their potential to mediate intercellular communication, modulating the phenotype of target cells. The natural properties and functions of EV are being exploited as biomarkers for disease diagnosis and prognosis, and as nano-bio-carriers for the development of new therapeutic strategies. EV have been particularly examined in the field of cancer, but are also increasingly investigated in other areas, like immune-related diseases and regenerative medicine. In this review, the therapeutic use of EV as drug delivery systems is described, balancing the advantages and drawbacks of different routes for their in vivo administration. Systemic and local delivery of EV are discussed, tackling the persisting difficulties in the assessment of their pharmacokinetics, pharmacodynamics and biodistribution in vivo. Finally, we discuss the future perspectives for incorporating EV into delivery systems and their use for an improved and controlled release of EV in vivo.

Extracellular vesicles derived from human umbilical cord mesenchymal stem cells alleviate rat hepatic ischemia-reperfusion injury by suppressing oxidative stress and neutrophil inflammatory response

Mesenchymal stem cells (MSCs) have been reported to exert therapeutic effects on immunoregulation, tissue repair, and regeneration from the bench to the bedside. Increasing evidence demonstrates that extracellular vesicles (EVs) derived from MSCs could contribute to these effects and are considered as a potential replacement for stem cell-based therapies. However, the efficacy and underlying mechanisms of EV-based treatment in hepatic ischemia-reperfusion injury (IRI) remain unclear. Here, we demonstrated that human umbilical cord MSC-EVs (huc-MSC-EVs) could protect against IRI-induced hepatic apoptosis by reducing the infiltration of neutrophils and alleviating oxidative stress in hepatic tissue in vivo. Meanwhile, huc-MSC-EVs reduced the respiratory burst of neutrophils and prevented hepatocytes from oxidative stress-induced cell death in vitro. Interestingly, we found that the mitochondria-located antioxidant enzyme, manganese superoxide dismutase (MnSOD), was encapsulated in huc-MSC-EVs and reduced oxidative stress in the hepatic IRI model. Knockdown of MnSOD in huc-MSCs decreased the level of MnSOD in huc-MSC-EVs and attenuated the antiapoptotic and antioxidant capacities of huc-MSC-EVs, which could be partially rescued by MnSOD mimetic manganese (III) 5,10,15,20-tetrakis (4-benzoic acid) porphyrin (MnTBAP). In summary, these findings provide new clues to reveal the therapeutic effects of huc-MSC-EVs on hepatic IRI and evaluate their preclinical application.-Yao, J., Zheng, J., Cai, J., Zeng, K., Zhou, C., Zhang, J., Li, S., Li, H., Chen, L., He, L., Chen, H., Fu, H., Zhang, Q., Chen, G., Yang, Y., Zhang, Y. Extracellular vesicles derived from human umbilical cord mesenchymal stem cells alleviate rat hepatic ischemia-reperfusion injury by suppressing oxidative stress and neutrophil inflammatory response.

CRISPR/Cas9 System: A Bacterial Tailor for Genomic Engineering

Microbes use diverse defence strategies that allow them to withstand exposure to a variety of genome invaders such as bacteriophages and plasmids. One such defence strategy is the use of RNA guided endonuclease called CRISPR-associated (Cas) 9 protein. The Cas9 protein, derived from type II CRISPR/Cas system, has been adapted as a versatile tool for genome targeting and engineering due to its simplicity and high efficiency over the earlier tools such as ZFNs and TALENs. With recent advancements, CRISPR/Cas9 technology has emerged as a revolutionary tool for modulating the genome in living cells and inspires innovative translational applications in different fields. In this paper we review the developments and its potential uses in the CRISPR/Cas9 technology as well as recent advancements in genome engineering using CRISPR/Cas9.

Human Mesenchymal Stem Cell Derived Exosomes Alleviate Type 2 Diabetes Mellitus by Reversing Peripheral Insulin Resistance and Relieving β-Cell Destruction

Exosomes are nanosized extracellular vesicles (EVs) that show great promise in tissue regeneration and injury repair as mesenchymal stem cell (MSC). MSC has been shown to alleviate diabetes mellitus (DM) in both animal models and clinical trials. In this study, we aimed to investigate whether exosomes from human umbilical cord MSC (hucMSC-ex) have a therapeutic effect on type 2 DM (T2DM). We established a rat model of T2DM using a high-fat diet and streptozotocin (STZ). We found that the intravenous injection of hucMSC-ex reduced blood glucose levels as a main paracrine approach of MSC. HucMSC-ex partially reversed insulin resistance in T2DM indirectly to accelerate glucose metabolism. HucMSC-ex restored the phosphorylation (tyrosine site) of the insulin receptor substrate 1 and protein kinase B in T2DM, promoted expression and membrane translocation of glucose transporter 4 in muscle, and increased storage of glycogen in the liver to maintain glucose homeostasis. HucMSC-ex inhibited STZ-induced β-cell apoptosis to restore the insulin-secreting function of T2DM. Taken together, exosomes from hucMSC can alleviate T2DM by reversing peripheral insulin resistance and relieving β-cell destruction, providing an alternative approach for T2DM treatment.

Progress in mesenchymal stem cell-based therapy for acute liver failure

Acute liver failure is a life-threatening clinical syndrome characterized by rapid development of hepatocellular necrosis leading to high mortality and resource costs. Numerous treatment strategies for acute liver failure simply prevent complications and decelerate disease progression. The only curative treatment for acute liver failure is liver transplantation, but there are many restrictions on the application of liver transplantation. In recent years, a growing number of studies have shown that stem cells can effectively treat acute liver failure. Several types of stem cells have been used to study liver diseases; mesenchymal stem cells are most commonly used because they are easy to obtain and present no ethical problems. The aims of this article are to review the current knowledge regarding therapeutic mechanisms of mesenchymal stem cells in acute liver failure, to discuss recent advancements in preclinical and clinical studies in the treatment of mesenchymal stem cells, and to summarize the methodological improvement of mesenchymal stem cell transplantation in treating liver failure.

Exosomes derived from TRAIL-engineered mesenchymal stem cells with effective anti-tumor activity in a mouse melanoma model

Exosomes are biological nano-sized vesicles (~30-200 nm in diameter) that are produced by a wide range of cells and play several roles in cell-cell communications. These vesicles contain membrane and cytoplasmic components of producing cells. Mesenchymal stem cells (MSCs) are the ideal producer of exosomes. The secreted vesicles from MSCs are promising biological vehicles for cell-free therapy in regenerative medicine, cancer therapy and targeted delivery of therapeutic agents to the tumor cells. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a promising member of the TNF family with selective effect on cancerous cells. Recent evidences showed that the membrane TRAIL-armed exosomes possess anti-tumor activity. However, the effect of in vivo administration of TRAIL-armed exosomes has not been reported so far. In the current study, mesenchymal stem cells expressing TRAIL/GFP proteins were prepared with the help of a non-viral vector based on polyethylenimine 25 kDa. Then, exosomes containing TRAIL protein (Exo-TRAIL) were isolated from the supernatant of genetically engineered MSCs and characterized. Antitumor activity of both MSC-derived exosomes and Exo-TRAIL was investigated in vitro and in vivo in three models. The results indicated that the co-injection of both Exo-TRAIL and tumor cells delayed the tumor appearance. Besides, the tumor volume/weight was efficiently decreased in tumor bearing mice. Moreover, it was shown that multi-dose injections of Exo-TRAIL reduced the tumor size while single dose treatment with Exo-TRAIL did not show significant anti-tumor activity. To conclude, these results suggested that MSC-derived Exo-TRAIL has a potential capacity for cancer treatment. [corrected].

Mesenchymal stromal cell-derived extracellular vesicles: regenerative and immunomodulatory effects and potential applications in sepsis

Mesenchymal stromal (stem) cells (MSCs) have multipotent differentiation capacity and exist in nearly all forms of post-natal organs and tissues. The immunosuppressive and anti-inflammatory properties of MSCs have made them an ideal candidate in the treatment of diseases, such as sepsis, in which inflammation plays a critical role. One of the key mechanisms of MSCs appears to derive from their paracrine activity. Recent studies have demonstrated that MSC-derived extracellular vesicles (MSC-EVs) are at least partially responsible for the paracrine effect. MSC-EVs transfer molecules (such as proteins/peptides, mRNA, microRNA and lipids) with immunoregulatory properties to recipient cells. MSC-EVs have been shown to mimic MSCs in alleviating sepsis and may serve as an alternative to whole cell therapy. Compared with MSCs, MSC-EVs may offer specific advantages due to lower immunogenicity and higher safety profile. The first two sections of the review discuss the preclinical and clinical findings of MSCs in sepsis. Next, we review the characteristics of EVs and MSC-EVs. Then, we summarize the mechanisms of MSC-EVs, including tissue regeneration and immunomodulation. Finally, our review presents the evidences that MSC-EVs are effective in treating models of sepsis. In conclusion, MSC-EVs may have the potential to become a novel therapeutic strategy for sepsis.

The extracellular vesicles-derived from mesenchymal stromal cells: A new therapeutic option in regenerative medicine

Mesenchymal stem cells (MSCs) are adult multipotent cells that due to their ability to homing to damaged tissues and differentiate into specialized cells, are remarkable cells in the field of regenerative medicine. It's suggested that the predominant mechanism of MSCs in tissue repair might be related to their paracrine activity. The utilization of MSCs for tissue repair is initially based on the differentiation ability of these cells; however now it has been revealed that only a small fraction of the transplanted MSCs actually fuse and survive in host tissues. Indeed, MSCs supply the microenvironment with the secretion of soluble trophic factors, survival signals and the release of extracellular vesicles (EVs) such as exosome. Also, the paracrine activity of EVs could mediate the cellular communication to induce cell-differentiation/self-renewal. Recent findings suggest that EVs released by MSCs may also be critical in the physiological function of these cells. This review provides an overview of MSC-derived extracellular vesicles as a hopeful opportunity to advance novel cell-free therapy strategies that might prevail over the obstacles and risks associated with the use of native or engineered stem cells. EVs are very stable; they can pass the biological barriers without rejection and can shuttle bioactive molecules from one cell to another, causing the exchange of genetic information and reprogramming of the recipient cells. Moreover, extracellular vesicles may provide therapeutic cargo for a wide range of diseases and cancer therapy.

Taking advantage of the potential of mesenchymal stromal cells in liver regeneration: Cells and extracellular vesicles as therapeutic strategies

Cell-based therapies for acute and chronic liver diseases are under continuous progress. Mesenchymal stem/stromal cells (MSCs) are multipotent cells able to migrate selectively to damaged tissue and contribute to its healing and regeneration. The MSC pro-regenerative effect occurs due to their immunomodulatory capacity and their ability to produce factors that promote cell protection and survival. Likewise, it has been observed that part of their paracrine effect is mediated by MSC-derived extracellular vesicles (EVs). EVs contain proteins, lipids and nucleic acids (DNA, mRNA, miRNA, lncRNA) from the cell of origin, allowing for intercellular communication. Recently, different studies have demonstrated that MSC-derived EVs could reproduce, at least in part, the biological effects obtained by MSC-based therapies. Moreover, due to EVs' stability for long periods of time and easy isolation methods they have become a therapeutic option to MSCs treatments. This review summarizes the latest results achieved in clinical trials using MSCs as cell therapy for liver regeneration, the role of EVs in liver physiopathology and the potential of MSCderived EVs as intercellular mediators and therapeutic tools in liver diseases.

Exosomes and regenerative medicine: state of the art and perspectives

Exosomes have attracted the attention of the scientific community in recent years due to their widespread distribution, their possible functions as biomarkers of disease, and their great potential to be applied as therapeutic agents. Exosomes carry proteins and nucleic acids that can facilitate their uptake by distant target cells through endocytosis, such that exosomes could be targeted to a specific cell or cells to enhance or interfere with specific biological processes. This review will mainly focus on their roles in tissue repair and regenerative processes. Exosomal engineering and their potential applications in tissue regeneration are also reviewed here as an outlook for future research.

Therapeutic effects of serum extracellular vesicles in liver fibrosis

The lack of approved therapies for hepatic fibrosis seriously limits medical management of patients with chronic liver disease. Since extracellular vesicles (EVs) function as conduits for intercellular molecular transfer, we investigated if EVs from healthy individuals have anti-fibrotic properties. Hepatic fibrogenesis or fibrosis in carbon tetrachloride (CCl₄)- or thioacetic acid-induced liver injury models in male or female mice were suppressed by serum EVs from normal mice (EVN) but not from fibrotic mice (EVF). CCl₄-treated mice undergoing EVN therapy also exhibited reduced levels of hepatocyte death, inflammatory infiltration, circulating AST/ALT levels and hepatic or circulating pro-inflammatory cytokines. Hepatic histology, liver function tests or circulating proinflammatory cytokine levels were unaltered in control mice receiving EVN. As determined using PKH26-labelled EVN, principal target cells included hepatic stellate cells (HSC; a normally quiescent fibroblastic cell that undergoes injury-induced activation and produces fibrosis during chronic injury) or hepatocytes which showed increased EVN binding after, respectively, activation or exposure to CCl₄. In vitro, EVN decreased proliferation and fibrosis-associated molecule expression in activated HSC, while reversing the inhibitory effects of CCl₄ or ethanol on hepatocyte proliferation. In mice, microRNA-34c, -151-3p, -483-5p, -532-5p and -687 were more highly expressed in EVN than EVF and mimics of these microRNAs (miRs) individually suppressed fibrogenic gene expression in activated HSC. A role for these miRs in contributing to EVN actions was shown by the ability of their corresponding antagomirs to individually and/or collectively block the therapeutic effects of EVN on activated HSC or injured hepatocytes. Similarly, the activated phenotype of human LX-2 HSC was attenuated by serum EVs from healthy human subjects and contained higher miR-34c, -151-3p, -483-5p or -532-5p than EVs from hepatic fibrosis patients. In conclusion, serum EVs from normal healthy individuals are inherently anti-fibrogenic and anti-fibrotic, and contain microRNAs that have therapeutic actions in activated HSC or injured hepatocytes.

Abbreviations: ALT: alanine aminotransferase; AST: aspartate aminotransferase; CCl₄: carbon tetrachloride; CCN2: connective tissue growth factor; E: eosin; EGFP: enhanced green fluorescent protein; EVs: extracellular vesicles; EVF: serum EVs from mice with experimental hepatic fibrosis; EVN: serum EVs from normal mice; H: hematoxylin; HSC: hepatic stellate cell; IHC: immunohistochemistry; IL: interleukin; MCP-1: monocyte chemotactic protein-1; miR: microRNA; mRNA: messenger RNA; NTA: nanoparticle tracking analysis; PCNA: proliferating cell nuclear antigen; qRT-PCR: quantitative real-time polymerase chain reaction; SDS-PAGE: sodium dodecyl sulphate – polyacrylamide gel electrophoresis; αSMA: alpha smooth muscle actin; TAA: thioacetic acid; TG: transgenic; TGF-β: transforming growth factor beta; TEM: transmission electron microscopy; TNFα: tumour necrosis factor alpha.

Newt cells secrete extracellular vesicles with therapeutic bioactivity in mammalian cardiomyocytes

Newts can regenerate amputated limbs and cardiac tissue, unlike mammals which lack broad regenerative capacity. Several signaling pathways involved in cell proliferation, differentiation and survival during newt tissue regeneration have been elucidated, however the factors that coordinate signaling between cells, as well as the conservation of these factors in other animals, are not well defined. Here we report that media conditioned by newt limb explant cells (A1 cells) protect mammalian cardiomyocytes from oxidative stress-induced apoptosis. The cytoprotective effect of A1-conditioned media was negated by exposing A1 cells to GW4869, which suppresses the generation of extracellular vesicles (EVs). A1-EVs are similar in diameter (~100–150 nm), structure, and share several membrane surface and cargo proteins with mammalian exosomes. However, isolated A1-EVs contain significantly higher levels of both RNA and protein per particle than mammalian EVs. Additionally, numerous cargo RNAs and proteins are unique to A1-EVs. Of particular note, A1-EVs contain numerous mRNAs encoding nuclear receptors, membrane ligands, as well as transcription factors. Mammalian cardiomyocytes treated with A1-EVs showed increased expression of genes in the PI3K/AKT pathway, a pivotal player in survival signaling. We conclude that newt cells secrete EVs with diverse, distinctive RNA and protein contents. Despite ~300 million years of evolutionary divergence between newts and mammals, newt EVs confer cytoprotective effects on mammalian cardiomyocytes.

Extracellular vesicles as potential biomarkers for alcohol- and drug-induced liver injury and their therapeutic applications

Extracellular vesicles (EVs) are small membranous vesicles originating from various cells and tissues, including the liver parenchymal hepatocytes and nonparenchymal cells such as Kupffer and stellate cells. Recently, the pathophysiological role of EVs, such as exosomes and microvesicles, has been increasingly recognized based on their properties of intercellular communications. These EVs travel through the circulating blood and interact with specific cells and then deliver their cargos such as nucleic acids and proteins into recipient cells. In addition, based on their stabilities, circulating EVs from body fluids such as blood, cerebrospinal fluid, urine, saliva, semen, breast milk and amniotic fluids are being studied as a valuable source of potential biomarkers for providing information about the physiological status of original cells or tissues. In addition, EVs are considered potential therapeutic agents due to their ability for intercellular communications between different cell types within the liver and between various organs through transfer of their cargos. In this review, we have briefly described recent advances in the characteristics and pathophysiological roles of EVs in alcoholic liver disease (ALD) or drug-induced liver injury (DILI) and discuss their advantages in the discovery of potential biomarkers and therapeutic agents.

Mesenchymal stem cell-derived extracellular vesicles: novel frontiers in regenerative medicine

Mesenchymal stem cells (MSCs) are multipotent stem cells that have gained significant attention in the field of regenerative medicine. The differentiation potential along with paracrine properties of MSCs have made them a key option for tissue repair. The paracrine functions of MSCs are applied through secreting soluble factors and releasing extracellular vesicles like exosomes and microvesicles. Extracellular vesicles are predominantly endosomal in origin and contain a cargo of miRNA, mRNA, and proteins that are transferred from their original cells to target cells. Recently it has emerged that extracellular vesicles alone are responsible for the therapeutic effect of MSCs in plenty of animal diseases models. Hence, MSC-derived extracellular vesicles may be used as an alternative MSC-based therapy in regenerative medicine. In this review we discuss MSC-derived extracellular vesicles and their therapeutic potential in various diseases.

Human Umbilical Cord MSC-Derived Exosomes Suppress the Development of CCl4-Induced Liver Injury through Antioxidant Effect

Mesenchymal stem cells (MSCs) have been increasingly applied into clinical therapy. Exosomes are small (30–100 nm in diameter) membrane vesicles released by different cell types and possess the similar functions with their derived cells. Human umbilical cord MSC-derived exosomes (hucMSC-Ex) play important roles in liver repair. However, the effects and mechanisms of hucMSC-Ex on liver injury development remain elusive. Mouse models of acute and chronic liver injury and liver tumor were induced by carbon tetrachloride (CCl₄) injection, followed by administration of hucMSC-Ex via the tail vein. Alleviation of liver injury by hucMSC-Ex was determined. We further explored the production of oxidative stress and apoptosis in the development of liver injury and compared the antioxidant effects of hucMSC-Ex with frequently used hepatic protectant, bifendate (DDB) in liver injury. hucMSC-Ex alleviated CCl₄-induced acute liver injury and liver fibrosis and restrained the growth of liver tumors. Decreased oxidative stress and apoptosis were found in hucMSC-Ex-treated mouse models and liver cells. Compared to bifendate (DDB) treatment, hucMSC-Ex presented more distinct antioxidant and hepatoprotective effects. hucMSC-Ex may suppress CCl₄-induced liver injury development via antioxidant potentials and could be a more effective antioxidant than DDB in CCl₄-induced liver tumor development.

Extracellular vesicle therapeutics for liver disease

Extracellular vesicles (EVs) are endogenous nanoparticles that play important roles in intercellular communication. Unmodified and engineered EVs can be utilized for therapeutic purposes. For instance, mesenchymal stem cell (MSC)-derived EVs have shown promise for tissue repair, while drug-loaded EVs have the potential to be used for cancer treatment. The liver is an ideal target for EV therapy due to the intrinsic regenerative capacity of hepatic tissue and the tropism of systemically injected nanovesicles for this organ. This review will give an overview of the potential of EV therapeutics in liver disease. Specifically, the mechanisms by which MSC-EVs induce liver repair will be covered. Moreover, the use of drug-loaded EVs for the treatment of hepatocellular carcinoma will also be discussed. Although there are several challenges associated with the clinical translation of EVs, these biological nanoparticles represent a promising new therapeutic modality for liver disease.

Exosomes as a novel pathway for regulating development and diseases of the skin

Exosomes are one of the most potent intercellular communicators, which are able to communicate with adjacent or distant cells. Exosomes deliver various bioactive molecules, including membrane receptors, proteins, mRNA and microRNA, to target cells and serve roles. Recent studies have demonstrated that exosomes may regulate the functions and diseases of the skin, which is the largest organ of the human body. The abnormal functions of the skin lead to the progression of scleroderma, melanoma, baldness and other diseases. A previous study has demonstrated that epithelial progenitor cells are rich in several subunits of exosomes that may maintain the proliferative capacity of these epithelial progenitor cells, which is essential for the development of the epidermis. Exosomes derived from human adipose mesenchymal stem cells accelerate skin wound healing by optimizing fibroblast properties; this is beneficial for the recovery of postoperative and other wounds. Exosomes derived from adipocytes promote melanoma migration and invasion through fatty acid oxidation; therefore, in the clinic, it may be possible to improve the prognosis of patients with melanoma by reducing their body fat content. Exosomes derived from keratinocytes modulate melanocyte pigmentation, which has been utilized as a novel mechanism for the regulation of pigmentation in conditions including Moynahan syndrome and albinism. Meanwhile, scleroderma patients with vascular abnormalities may experience decreased serum exosome levels; it may therefore be possible to detect the exosome content in sera in order to diagnose and treat scleroderma. In addition, the use of exosomes has been suggested to promote or enhance hair growth, which has been demonstrated to be highly effective. These studies have provided new opportunities and therapeutic strategies for understanding how exosomes regulate intercellular communication in pathological processes of the skin.

BMSCs-derived miR-223-containing exosomes contribute to liver protection in experimental autoimmune hepatitis

Autoimmune hepatitis is a chronic inflammatory disease in the liver with potential to the development of liver fibrosis. Recent evidences suggest that bone marrow derived mesenchymal stem cells (BMSCs) may exert its therapeutic activity through exosomes. Moreover, miR-223 is highly expressed in BMSCs and plays an important role in autoimmune diseases. Therefore, in this study, hepatoprotective role of BMSCs and miR-223 was investigated in both mice and hepatocytes. Liver antigen S100 was used to establish autoimmune hepatitis model in mice while LPS and ATP were used to establish cell injury model in hepatocyte. Before the experiments, BMSCs were infected with pre-miR-223 and transfected with miR-223 inhibitor respectively. Exosomes from bone marrow stem cells were isolated by ultracentrifugation. Liver injury was evaluated by serum levels of ALT and AST as well as liver histology. Inflammation and cell death were examined by inflammatory cytokines and lactase dehydrogenase respectively. Both BMSCs-exo and BMSCs-exo^miR-223(+) significantly reversed either S100 or LPS/ATP induced injury in mice and hepatocytes. Meanwhile, the expressions of cytokines, NLRP3 and caspase-1 were also downregulated by BMSCs-exo and BMSCs-exo^miR-223(+) at both protein and mRNA levels in mice and hepatocytes. Moreover, BMSCs-exo^miR-223(-) reverses the effects of BMSCs-exo and BMSCs-exo^miR-223(+) in mouse AIH and in hepatocytes. In conclusion, bone marrow stem cell derived exosomes can protect liver injury in an experimental model of autoimmune hepatitis and the mechanism could be related to exosomal miR-223 regulation of NLRP3 and caspase-1.

Selenium-Dependent Glutathione Peroxidases During Tumor Development

Five out of eight human glutathione peroxidases (GPxes) are selenoproteins and thus their expression depends on the selenium (Se) supply. Most Se-dependent GPxes are downregulated in tumor cells, while only GPx2 is considerably upregulated. Whether expression profiles of GPxes predict tumor development and patient survival is controversially discussed. Also, results from in vitro and in vivo studies modulating the expression of GPx isoforms provide evidence for both anti- and procarcinogenic mechanisms. GPxes are able to reduce hydroperoxides, which otherwise would damage DNA, possibly resulting in DNA mutations, modulate redox-sensitive signaling pathways affecting proliferation, differentiation, and cellular metabolism or initiate cell death. Considering these different processes, the role and functions of individual Se-dependent GPx isoforms will be discussed herein in the context of tumorigenesis.

Glutathione peroxidases as oncotargets

Oxidative stress is a disturbance in the equilibrium among free radicals, reactive oxygen species, and endogenous antioxidant defense mechanisms. Oxidative stress is a result of imbalance between the production of reactive oxygen and the biological system's ability to detoxify the reactive intermediates or to repair the resulting damage. Mounting evidence has implicated oxidative stress in various physiological and pathological processes, including DNA damage, proliferation, cell adhesion, and survival of cancer cells. Glutathione peroxidases (GPxs) (EC 1.11.1.9) are an enzyme family with peroxidase activity whose main biological roles are to protect organisms from oxidative damage by reducing lipid hydroperoxides as well as free hydrogen peroxide. Currently, 8 sub-members of GPxs have been identified in humans, all capable of reducing H₂O₂ and soluble fatty acid hydroperoxides. A large number of publications has demonstrated that GPxs have significant roles in different stages of carcinogenesis. In this review, we will update recent progress in the study of the roles of GPxs in cancer. Better mechanistic understanding of GPxs will potentially contribute to the development and advancement of improved cancer treatment models.

Mesenchymal Stem/Stromal Cell-Derived Extracellular Vesicles and Their Potential as Novel Immunomodulatory Therapeutic Agents

Extracellular vesicles (EVs), such as exosomes and microvesicles, have been identified as mediators of a newly-discovered intercellular communication system. They are essential signaling mediators in various physiological and pathophysiological processes. Depending on their origin, they fulfill different functions. EVs of mesenchymal stem/stromal cells (MSCs) have been found to promote comparable therapeutic activities as MSCs themselves. In a variety of in vivo models, it has been observed that they suppress pro-inflammatory processes and reduce oxidative stress and fibrosis. By switching pro-inflammatory into tolerogenic immune responses, MSC-EVs very likely promote tissue regeneration by creating a pro-regenerative environment allowing endogenous stem and progenitor cells to successfully repair affected tissues. Accordingly, MSC-EVs provide a novel, very promising therapeutic agent, which has already been successfully applied to humans. However, the MSC-EV production process has not been standardized, yet. Indeed, a collection of different protocols has been used for the MSC-EV production, characterization and application. By focusing on kidney, heart, liver and brain injuries, we have reviewed the major outcomes of published MSC-EV in vivo studies.

Role of mesenchymal stem cells, their derived factors, and extracellular vesicles in liver failure

Liver failure is a severe clinical syndrome with a poor prognosis. Mesenchymal stem cell (MSC) transplantation has emerged as a new intervention in treating liver failure. It is conventionally recognized that MSCs exert their therapeutic effect mainly through transdifferentiation. Recently, published articles have shown that MSCs work in liver failure by secreting trophic and immunomodulatory factors as well as extracellular vesicles (EVs) before transdifferentiation. In particular,MSC-derived EVs have shown similar curative effects as MSCs. Here we review the role of MSCs as well as their derived factors and EVs in liver failure and discuss the use of MSC-derived EVs instead of intact MSCs in treating liver failure.

Exosomes Derived from Human Umbilical Cord Mesenchymal Stem Cells Relieve Inflammatory Bowel Disease in Mice

Exosomes secreted by mesenchymal stem cells (MSCs) have shown repairing effects on several tissue injury diseases. In this study, we aimed to investigate the effects of exosomes released from human umbilical cord mesenchymal stem cells (hucMSCs) on the treatment of dextran sulfate sodium- (DSS-) induced inflammatory bowel disease (IBD) and to explore the underlying mechanism. We found that indocyanine green (ICG) labeled exosomes homed to colon tissues of IBD mice at 12 hours after injection. Exosomes significantly relieved the severity of IBD in mice as hucMSCs. The expression of IL-10 gene was increased while that of TNF-α, IL-1β, IL-6, iNOS, and IL-7 genes was decreased in the colon tissues and spleens of exosomes-treated mice. Furthermore, the infiltration of macrophages into the colon tissues was decreased by exosome treatment in IBD mice. In addition, we provided evidence that in vitro coculture with exosomes inhibited the expression of iNOS and IL-7 in mouse enterocoelia macrophages. Moreover, we found that the expression of IL-7 was higher in the colon tissues of colitis patients than that of healthy controls. Our findings suggest that exosomes from hucMSCs have profound effects on alleviating DSS-induced IBD and may exert their impact through the modulation of IL-7 expression in macrophages.