Mesenchymal Stem Cell-Derived Extracellular Vesicles in Liver Immunity and Therapy

Plant-derived exosome-like nanoparticles - from Laboratory to factory, a landscape of application, challenges and prospects

Recent decades have witnessed substantial interest in extracellular vesicles (EVs) due to their crucial role in intercellular communication across various biological processes. Among these, plant-derived exosome-like Nanoparticles (ELNs) have rapidly gained recognition as highly promising candidates. ELNs, characterized by diverse sources, cost-effective production, and straightforward isolation, present a viable option for preventing and treating numerous diseases. Furthermore, ELNs hold significant potential as carriers for natural or engineered drugs, enhancing their attractiveness and drawing considerable attention in science and medicine. However, translating ELNs into clinical applications poses several challenges. This study explores these challenges and offers critical insights into potential research directions. Additionally, it provides a forward-looking analysis of the industrial prospects for ELNs. With their broad applications and remarkable potential, ELNs stand at the forefront of biomedical innovation, poised to revolutionize disease management and drug delivery paradigms in the coming years.

Mitochondria: a breakthrough in combating rheumatoid arthritis

As a chronic autoimmune disease with complex aetiology, rheumatoid arthritis (RA) has been demonstrated to be associated with mitochondrial dysfunction since mitochondrial dysfunction can affect the survival, activation, and differentiation of immune and non-immune cells involved in the pathogenesis of RA. Nevertheless, the mechanism behind mitochondrial dysfunction in RA remains uncertain. Accordingly, this review addresses the possible role and mechanisms of mitochondrial dysfunction in RA and discusses the potential and challenges of mitochondria as a potential therapeutic strategy for RA, thereby providing a breakthrough point in the prevention and treatment of RA.

Exosomes derived from Baicalin-pretreated bone mesenchymal stem cells improve Th17/Treg imbalance after hepatic ischemia-reperfusion via FGF21 and the JAK2/STAT3 pathway

Baicalin is an active compound extracted from Scutellaria baicalensis with antioxidant and anti-inflammatory properties. Bone mesenchymal stem cells (BMSCs)-derived exosomes have shown promise for the treatment of hepatic ischemia-reperfusion (I/R) injury. This study aims to investigate the role of Baicalin-pretreated BMSCs-derived exosomes in hepatic I/R injury and its mechanisms. BMSCs were pretreated with or without Baicalin, and their exosomes (Ba-Exo and Exo) were collected and characterized. These exosomes were administered to mice via tail vein injection. Treatment with Exo and Ba-Exo significantly suppressed the elevation of ALT and AST induced by hepatic injury. Additionally, both Exo and Ba-Exo treatments resulted in a reduction in the liver weight-to-body weight ratio. RT-PCR results revealed a significant downregulation of pro-inflammatory cytokines with Exo and Ba-Exo treatment. Both Exo and Ba-Exo treatment improved the Th17/Treg cell imbalance induced by I/R and reduced hepatic injury. Additionally, exosomes were cocultured with normal liver cells, and the expression of fibroblast growth factor 21 (FGF21) in liver cells was elevated through Ba-Exo treatment. After treatment, the JAK2/STAT3 pathway was inhibited, and FOXO1 expression was upregulated. Finally, recombinant FGF21 was injected into mouse tail veins to assess its effects. Recombinant FGF21 injection further inhibited the JAK2/STAT3 pathway, increased FOXO1 expression, and improved the Th17/Treg cell imbalance. In conclusion, this study confirms the protective effects of Exo and Ba-Exo against hepatic I/R injury. Ba-Exo mitigates hepatic I/R injury, achieved through inducing FGF21 expression in liver cells, inhibiting the JAK2/STAT3 pathway, and activating FOXO1 expression. Therefore, baicalin pretreatment emerges as a promising strategy to enhance the therapeutic capability of BMSCs-derived exosomes for hepatic I/R.

Exosome prospects in the diagnosis and treatment of non-alcoholic fatty liver disease

The growing prevalence of NAFLD and its global health burden have provoked considerable research on possible diagnostic and therapeutic options for NAFLD. Although various pathophysiological mechanisms and genetic factors have been identified to be associated with NAFLD, its treatment remains challenging. In recent years, exosomes have attracted widespread attention for their role in metabolic dysfunctions and their efficacy as pathological biomarkers. Exosomes have also shown tremendous potential in treating a variety of disorders. With increasing evidence supporting the significant role of exosomes in NAFLD pathogenesis, their theragnostic potential has become a point of interest in NAFLD. Expectedly, exosome-based treatment strategies have shown promise in the prevention and amelioration of NAFLD in preclinical studies. However, there are still serious challenges in preparing, standardizing, and applying exosome-based therapies as a routine clinical option that should be overcome. Due to the great potential of this novel theragnostic agent in NAFLD, further investigations on their safety, clinical efficacy, and application standardization are highly recommended.

Therapeutic Application of Extracellular Vesicles Derived from Mesenchymal Stem Cells in Domestic Animals

Recently, the therapeutic potential of extracellular vesicles (EVs) derived from mesenchymal stem cells (MSCs) has been extensively studied in both human and veterinary medicine. EVs are nano-sized particles containing biological components commonly found in other biological materials. For that reason, EV isolation and characterization are critical to draw precise conclusions during their investigation. Research on EVs within veterinary medicine is still considered in its early phases, yet numerous papers were published in recent years. The conventional adult tissues for deriving MSCs include adipose tissue and bone marrow. Nonetheless, alternative sources such as synovial fluid, endometrium, gingiva, and milk have also been intermittently used. Fetal adnexa are amniotic membrane/fluid, umbilical cord and Wharton's jelly. Cells derived from fetal adnexa exhibit an intermediate state between embryonic and adult cells, demonstrating higher proliferative and differentiative potential and longer telomeres compared to cells from adult tissues. Summarized here are the principal and recent preclinical and clinical studies performed in domestic animals such as horse, cattle, dog and cat. To minimize the use of antibiotics and address the serious issue of antibiotic resistance as a public health concern, they will undoubtedly also be utilized in the future to treat infections in domestic animals. A number of concerns, including large-scale production with standardization of EV separation and characterization techniques, must be resolved for clinical application.

Bone mesenchymal stem cells improve cholestatic liver fibrosis by targeting ULK1 to regulate autophagy through PI3K/AKT/mTOR pathway

Cholestatic liver disease (CLD) is a severe disease, which can progress to liver cirrhosis, even liver cancer. Hepatic stellate cells (HSCs) activation plays a crucial role in CLD development. Bone mesenchymal stem cells (BMSCs) treatment was demonstrated to be beneficial in liver diseases. However, the therapeutic effect and mechanism of BMSCs on CLD are poorly known. In the present study, we investigated the therapeutic effects and underlying mechanisms of BMSCs transplantation in mouse models of bile duct ligation-induced cholestatic liver fibrosis (CLF). The results revealed that BMSCs significantly improved liver function and reduced the formation of fibrosis after portal vein transplantation. Mechanistically, after coculturing BMSCs and HSCs, we identified that BMSCs alleviated starvation-induced HSCs activation. Further, BMSCs inhibited HSCs activation by decreasing autophagy, and PI3K/AKT/mTOR pathway was involved in the regulation. More importantly, ULK1 is identified as the main autophagy-related gene regulated by BMSCs in HSCs autophagy. Overexpression of ULK1 reversed the suppression of HSCs autophagy by BMSCs. Collectively, our results provide a theoretical basis for BMSCs targeting ULK1 to attenuate HSCs autophagy and activation and suggest that BMSCs or ULK1 may be an alternative therapeutic approach/target for the treatment of CLF.

Large extracellular vesicles from induced pluripotent stem cell-marrow stem cells enhance limb angiogenesis via ERK/MAPK

Aim: This study aims to investigate the effects of large extracellular vesicles (EVs) induced by pluripotent stem cell-derived mesenchymal stem cells on lower limb ischemic disease and explore its potential mechanisms. Materials & methods: The pathology of muscles was accessed by H&E staining and immunofluorescence staining. In vitro, we conducted wound-healing assay, tube formation assay, RT qPCR, ELISA, RNA sequencing and proteomic analysis. Results: iMSCs-lEVs alleviated the injury of ischemic lower limb and promoted the recovery of lower limb function. In vitro, iMSCs-lEVs promoted the proliferation, migration, and angiogenesis of HMEC-1 cells by regulating the ERK/MAPK signing pathway. Conclusion: This study demonstrated that iMSCs-lEVs promoted endothelial cell angiogenesis via the ERK/MAPK signaling pathway, thereby improving function after lower limb ischemic injury.

Effects of Mesenchymal Stem Cells-Derived Extracellular Vesicles on Inhibition of Hepatic Fibrosis by Delivering miR-200a

BACKGROUND

Hepatic fibrosis (HF) is a common pathological feature of chronic hepatic diseases. We aimed to illuminate the significance of amniotic mesenchymal stem cells (AMSCs)-derived extracellular vesicles (AMSCs-EVs) in HF.

METHODS

Human AMSCs-EVs were isolated and identified. HF mice were constructed and treated with EVs. The fibrosis was observed by staining experiments and Western blot (WB) assay. Alanine aminotransferase (ALT), aspartate aminotransferase (AST), total bilirubin (TBIL), and hepatic hydroxyproline (Hyp) were detected to confirm liver function. For the in vitro experiments, human hepatic stellate cells were induced with transforming growth factor-β and treated with EVs. To measure the degree of HF, the expression of alpha-smooth muscle actin (α-SMA) and Collagen I was detected by WB assay, and cell proliferation was detected by cell counting kit 8 assay. The levels of miR-200a, Zinc finger E-box binding homeobox 1 (ZEB1), and phosphoinositide-3-kinase regulatory subunit 3 (PIK3R3) were detected by WB and real-time quantitative polymerase chain reaction. The binding of ZEB1 to PIK3R3 and miR-200a to ZEB1 was analyzed by chromatin immunoprecipitation and dual luciferase assays to validate their relationships.

RESULTS

Human AMSCs and AMSCs-EVs were obtained. Serum ALT, AST, TBIL, and hepatic Hyp were increased, implying the fibrosis degree was aggravated in HF mice, which was decreased again after EV treatment. EVs inhibited HF degree by reducing α-SMA and Collagen I and promoting cell proliferation. AMSCs-EVs delivered miR-200a into hepatocytes, which up-regulated miR-200a expression, inhibited ZEB1 expression, and reduced its enrichment on the PIK3R3 promoter, therefore inhibiting PIK3R3 expression and alleviating HF. Overexpression of ZEB1 or PIK3R3 attenuated the anti-fibrotic effect of AMSCs-EVs.

CONCLUSION

Human AMSCs-derived EVs mediated miR-200a delivery and inhibition of intracellular ZEB1/PIK3R3 axis to exert anti-fibrosis effects.

Mesenchymal stromal cell-derived extracellular vesicles therapy openings new translational challenges in immunomodulating acute liver inflammation

Inflammation plays a critical role in conditions such as acute liver failure, acute-on-chronic liver failure, and ischemia-reperfusion-induced liver injury. Various pathogenic pathways contribute to liver inflammation, involving inflammatory polarization of macrophages and Küpffer cells, neutrophil infiltration, dysregulation of T cell subsets, oxidative stress, and activation of hepatic stellate cells. While mesenchymal stromal cells (MSCs) have demonstrated beneficial properties, their clinical translation is limited by their cellular nature. However, MSC-derived extracellular vesicles (MSC-EVs) have emerged as a promising cell-free therapeutic approach for immunomodulation. MSC-EVs naturally mirror their parental cell properties, overcoming the limitations associated with the use of MSCs. In vitro and in vivo preclinical studies have demonstrated that MSC-EVs replicate the beneficial effects of MSCs in liver injury. This includes the reduction of cell death and oxidative stress, improvement of hepatocyte function, induction of immunomodulatory effects, and mitigation of cytokine storm. Nevertheless, MSC-EVs face challenges regarding the necessity of defining consistent isolation methods, optimizing MSCs culture conditions, and establishing quality control measures for EV characterization and functional assessment. By establishing standardized protocols, guidelines, and affordable cost mass production, clinicians and researchers will have a solid foundation to conduct further studies, validate the therapeutic efficacy of MSC-EVs, and ultimately pave the way for their clinical implementation in acute liver injury.

Mesenchymal Stem Cells and Extracellular Vesicles: Therapeutic Potential in Organ Transplantation

At present, organ transplantation remains the most appropriate therapy for patients with end-stage organ failure. However, the field of organ transplantation is still facing many challenges, including the shortage of organ donors, graft function damage caused by organ metastasis, and antibody-mediated immune rejection. It is therefore urgently necessary to find new and effective treatment. Stem cell therapy has been regarded as a "regenerative medicine technology." Mesenchymal stem cells (MSCs), as the most common source of cells for stem cell therapy, play an important role in regulating innate and adaptive immune responses and have been widely used in clinical trials for the treatment of autoimmune and inflammatory diseases. Increasing evidence has shown that MSCs mainly rely on paracrine pathways to exert immunomodulatory functions. In addition, mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) are the main components of paracrine substances of MSCs. Herein, an overview of the application of the function of MSCs and MSC-EVs in organ transplantation will focus on the progress reported in recent experimental and clinical findings and explore their uses for graft preconditioning and recipient immune tolerance regulation. Additionally, the limitations on the use of MSC and MSC-EVs are also discussed, covering the isolation of exosomes and preservation techniques. Finally, the opportunities and challenges for translating MSCs and MSC-EVs into clinical practice of organ transplantation are also evaluated.

Mesenchymal Stem Cell-Derived Extracellular Vesicles Alleviate Brain Damage Following Subarachnoid Hemorrhage via the Interaction of miR-140-5p and HDAC7

Subarachnoid hemorrhage (SAH) triggers severe neuroinflammation and cognitive impairment, where microglial M1 polarization exacerbates the injury and M2 polarization mitigates damage. Mesenchymal stem cell-derived extracellular vesicles (MSC-EVs), carrying microRNA (miR)-140-5p, offer therapeutic promise by targeting the cAMP/PKA/CREB pathway and modulating microglial responses, demonstrating a novel approach for addressing SAH-induced brain injury. This research explored the role of miR-140-5p delivered by MSC-EVs in mitigating brain damage following SAH. Serum from SAH patients and healthy individuals was analyzed for miR-140-5p and cAMP levels. The association between miR-140-5p levels, brain injury severity, and patient survival was examined, along with the target relationship between miR-140-5p and histone deacetylases 7 (HDAC7). MSC-EVs were characterized for their ability to cross the blood-brain barrier and modulate the HDAC7/AKAP12/cAMP/PKA/CREB axis, reducing M1 polarization and inflammation. The therapeutic effect of MSC-EV-miR-140-5p was demonstrated in an SAH mouse model, showing reduced neuronal apoptosis and improved neurological function. This study highlights the potential of MSC-EV-miR-140-5p in mitigating SAH-induced neuroinflammation and brain injury, providing a foundation for developing MSC-EV-based treatments for SAH.

Applications of emerging extracellular vesicles technologies in the treatment of inflammatory diseases

The emerging extracellular vesicles technologies is an advanced therapeutic approach showing promising potential for addressing inflammatory diseases. These techniques have been proven to have positive effects on immune modulation and anti-inflammatory responses. With these advancements, a comprehensive review and update on the role of extracellular vesicles in inflammatory diseases have become timely. This review aims to summarize the research progress of extracellular vesicle technologies such as plant-derived extracellular vesicles, milk-derived extracellular vesicles, mesenchymal stem cell-derived extracellular vesicles, macrophage-derived extracellular vesicles, etc., in the treatment of inflammatory diseases. It elucidates their potential significance in regulating inflammation, promoting tissue repair, and treating diseases. The goal is to provide insights for future research in this field, fostering the application and development of extracellular vesicle technology in the treatment of inflammatory diseases.

Beyond Traditional Medicine: EVs-Loaded Hydrogels as a Game Changer in Disease Therapeutics

Extracellular vesicles (EVs), especially exosomes, have shown great therapeutic potential in the treatment of diseases, as they can target cells or tissues. However, the therapeutic effect of EVs is limited due to the susceptibility of EVs to immune system clearance during transport in vivo. Hydrogels have become an ideal delivery platform for EVs due to their good biocompatibility and porous structure. This article reviews the preparation and application of EVs-loaded hydrogels as a cell-free therapy strategy in the treatment of diseases. The article also discusses the challenges and future outlook of EVs-loaded hydrogels.

Mesenchymal Stem Cell-Derived Exosomes in Various Chronic Liver Diseases: Hype or Hope?

Chronic liver conditions are associated with high mortality rates and have a large adverse effect on human well-being as well as a significant financial burden. Currently, the only effective treatment available for the effects of liver failure and cirrhosis resulting from the progression of several chronic liver diseases is liver transplantation carried out at the original location. This implies that developing novel and effective treatments is imperative. Regenerative medicine has long been associated with stem cell therapy. Mesenchymal stem cells (MSCs), a type of cell with great differentiation potential, have become the preferred source for stem cell therapy. According to recent studies, MSCs' paracrine products-rather than their capacity for differentiation-play a significant therapeutic effect. MSC exosomes, a type of extracellular vesicle (MSC-EV), came into view as the paracrine substances of MSCs. According to research, MSC exosomes can maintain tissue homeostasis, which is necessary for healthy tissue function. All tissues contain them, and they take part in a variety of biological activities that support cellular activity and tissue regeneration in order to preserve tissue homeostasis. The outcomes support the use of MSCs and the exosomes they produce as a therapeutic option for a range of diseases. This review provides a brief overview of the source of MSC-EVs and outlines their physiological roles and biochemical capabilities. The elucidation of the role of MSC-EVs in the recovery and repair of hepatic tissues, as well as their contribution to maintaining tissue homeostasis, is discussed in relation to different chronic liver diseases. This review aims to provide new insights into the unique roles that MSC-EVs play in the treatment of chronic liver diseases.

Extracellular vesicles from adipose stem cells ameliorate allergic rhinitis in mice by immunomodulatory

Background

Human adipose tissue-derived stem cells (hADSCs) exert potent immunosuppressive effects in the allogeneic transplantation treatment. In mouse model of allergic rhinitis (AR), ADSCs partially ameliorated AR. However, no study has evaluated the potential therapeutic effects of hADSC-derived extracellular vesicles (hADSC-EVs) on AR.

Methods

Female BALB/c mice were sensitized and challenged with ovalbumin (OVA) to induce AR. One day after the last nasal drop, each group received phosphate buffered saline (PBS) or hADSC-EVs treatment. Associated symptoms and biological changes were then assessed.

Results

hADSC-EV treatment significantly alleviated nasal symptoms, and reduced inflammatory infiltration. Serum levels of OVA-specific IgE, interleukin (IL)-4 and interferon (IFN)-γ were all significantly reduced. The mRNA levels of IL-4 and IFN-γ in the spleen also changed accordingly. The T helper (Th)1/Th2 cell ratio increased. The treatment efficacy index of hADSC-EV was higher than that of all human-derived MSCs in published reports on MSC treatment of AR. ADSC-EVs exhibited a greater therapeutic index in most measures when compared to our previous treatment involving ADSCs.

Conclusion

These results demonstrated that hADSC-EVs could ameliorate the symptoms of AR by modulating cytokine secretion and Th1/Th2 cell balance. hADSC-EVs could potentially be a viable therapeutic strategy for AR. Further animal studies are needed to elucidate the underlying mechanisms and to optimize potential clinical protocols.

The Crosstalk between Mesenchymal Stromal/Stem Cells and Hepatocytes in Homeostasis and under Stress

Liver diseases, characterized by high morbidity and mortality, represent a substantial medical problem globally. The current therapeutic approaches are mainly aimed at reducing symptoms and slowing down the progression of the diseases. Organ transplantation remains the only effective treatment method in cases of severe liver pathology. In this regard, the development of new effective approaches aimed at stimulating liver regeneration, both by activation of the organ's own resources or by different therapeutic agents that trigger regeneration, does not cease to be relevant. To date, many systematic reviews and meta-analyses have been published confirming the effectiveness of mesenchymal stromal cell (MSC) transplantation in the treatment of liver diseases of various severities and etiologies. However, despite the successful use of MSCs in clinical practice and the promising therapeutic results in animal models of liver diseases, the mechanisms of their protective and regenerative action remain poorly understood. Specifically, data about the molecular agents produced by these cells and mediating their therapeutic action are fragmentary and often contradictory. Since MSCs or MSC-like cells are found in all tissues and organs, it is likely that many key intercellular interactions within the tissue niches are dependent on MSCs. In this context, it is essential to understand the mechanisms underlying communication between MSCs and differentiated parenchymal cells of each particular tissue. This is important both from the perspective of basic science and for the development of therapeutic approaches involving the modulation of the activity of resident MSCs. With regard to the liver, the research is concentrated on the intercommunication between MSCs and hepatocytes under normal conditions and during the development of the pathological process. The goals of this review were to identify the key factors mediating the crosstalk between MSCs and hepatocytes and determine the possible mechanisms of interaction of the two cell types under normal and stressful conditions. The analysis of the hepatocyte-MSC interaction showed that MSCs carry out chaperone-like functions, including the synthesis of the supportive extracellular matrix proteins; prevention of apoptosis, pyroptosis, and ferroptosis; support of regeneration; elimination of lipotoxicity and ER stress; promotion of antioxidant effects; and donation of mitochondria. The underlying mechanisms suggest very close interdependence, including even direct cytoplasm and organelle exchange.

Mesenchymal stem/stromal cells- a principal element for tumour microenvironment heterogeneity

The heterogeneity of the tumor microenvironment (TME) is a major obstacle in cancer treatment, making most therapeutic interventions palliative rather than curative. Previous studies have suggested that the reason for the low efficacy of immunotherapy and the relapse of the original responders over time may be due to the complex network of mesenchymal stem/stromal cells (MSCs), a population of multipotent progenitor cells existing in a variety of tissues. Cancer-associated MSCs (CA-MSCs) have already been isolated from various types of tumors and are characterized by their vigorous pro-tumorigenic functions. Although the roles of CA-MSCs from different sources vary widely, their origins are still poorly understood. Current evidence suggests that when local resident or distally recruited MSCs interact with tumor cells and other components in the TME, "naïve" MSCs undergo genetic and functional changes to form CA-MSCs. In this review, we mainly focus on the multiple roles of CA-MSCs derived from different sources, which may help in elucidating the formation and function of the entire TME, as well as discover innovative targets for anti-cancer therapies.

Non-coding RNAs: The potential biomarker or therapeutic target in hepatic ischemia-reperfusion injury

Hepatic ischemia-reperfusion injury (HIRI) is the major complication of liver surgery and liver transplantation, that may increase the postoperative morbidity, mortality, tumor progression, and metastasis. The underlying mechanisms have been extensively investigated in recent years. Among these, oxidative stress, inflammatory responses, immunoreactions, and cell death are the most studied. Non-coding RNAs (ncRNAs) are defined as the RNAs that do not encode proteins, but can regulate gene expressions. In recent years, ncRNAs have emerged as research hotspots for various diseases. During the progression of HIRI, ncRNAs are differentially expressed, while these dysregulations of ncRNAs, in turn, have been verified to be related to the above pathological processes involved in HIRI. ncRNAs mainly contain microRNAs, long ncRNAs, and circular RNAs, some of which have been reported as biomarkers for early diagnosis or assessment of liver damage severity, and as therapeutic targets to attenuate HIRI. Here, we briefly summarize the common pathophysiology of HIRI, describe the current knowledge of ncRNAs involved in HIRI in animal and human studies, and discuss the potential of ncRNA-targeted therapeutic strategies. Given the scarcity of clinical trials, there is still a long way to go from pre-clinical to clinical application, and further studies are needed to uncover their potential as therapeutic targets.

Isolation, culture, and delivery considerations for the use of mesenchymal stem cells in potential therapies for acute liver failure

Acute liver failure (ALF) is a high-mortality syndrome for which liver transplantation is considered the only effective treatment option. A shortage of donor organs, high costs and surgical complications associated with immune rejection constrain the therapeutic effects of liver transplantation. Recently, mesenchymal stem cell (MSC) therapy was recognized as an alternative strategy for liver transplantation. Bone marrow mesenchymal stem cells (BMSCs) have been used in clinical trials of several liver diseases due to their ease of acquisition, strong proliferation ability, multipotent differentiation, homing to the lesion site, low immunogenicity and anti-inflammatory and antifibrotic effects. In this review, we comprehensively summarized the harvest and culture expansion strategies for BMSCs, the development of animal models of ALF of different aetiologies, the critical mechanisms of BMSC therapy for ALF and the challenge of clinical application.

[Exosomes in the life cycle of viruses and the pathogenesis of viral infections]

Exosomes are extracellular vesicles of endosomal origin, with a bilayer membrane, 30160 nm in diameter. Exosomes are released from cells of different origins and are detected in various body fluids. They contain nucleic acids, proteins, lipids, metabolites and can transfer the contents to recipient cells. Exosome biogenesis involves cellular proteins of the Rab GTPase family and the ESCRT system, which regulate budding, vesicle transport, molecule sorting, membrane fusion, formation of multivesicular bodies and exosome secretion. Exosomes are released from cells infected with viruses and may contain viral DNA and RNA, as well as mRNA, microRNA, other types of RNA, proteins and virions. Exosomes are capable of transferring viral components into uninfected cells of various organs and tissues. This review analyzes the impact of exosomes on the life cycle of widespread viruses that cause serious human diseases: human immunodeficiency virus (HIV-1), hepatitis B virus, hepatitis C virus, SARS-CoV-2. Viruses are able to enter cells by endocytosis, use molecular and cellular pathways involving Rab and ESCRT proteins to release exosomes and spread viral infections. It has been shown that exosomes can have multidirectional effects on the pathogenesis of viral infections, suppressing or enhancing the course of diseases. Exosomes can potentially be used in noninvasive diagnostics as biomarkers of the stage of infection, and exosomes loaded with biomolecules and drugs - as therapeutic agents. Genetically modified exosomes are promising candidates for new antiviral vaccines.

Role of adipocyte-derived extracellular vesicles during the progression of liver inflammation to hepatocellular carcinoma

Extracellular vesicles are membrane-bound cargos that vary in size and are stably transported through various bodily fluids. Extracellular vesicles communicate information between the cells and organs. Extracellular vesicles from the diseased cells alter cellular responses of the recipient cells contributing to disease progression. In obesity, adipocytes become hypertrophic and the extracellular vesicles from these dysfunctional adipocytes showed altered cargo contents instigating pathophysiological response leading to chronic liver diseases. In this review, the role of adipocyte-derived extracellular vesicles on the progression of liver inflammation, fibrosis, cirrhosis, and hepatocellular carcinoma are extensively discussed. Newer approaches are crucial to take advantage of extracellular vesicles and their content as biomarkers to diagnose initial liver inflammation before reaching to an irreversible liver failure stage.

Extracellular vesicles in fatty liver disease and steatohepatitis: Role as biomarkers and therapeutic targets

Non-alcoholic fatty liver disease (NAFLD) and alcohol-associated liver disease (ALD) are characterized by lipid deposition in hepatocytes in the absence or presence of excessive alcohol consumption, respectively, ranging from simple steatosis to non-alcoholic steatohepatitis (NASH) or alcoholic hepatitis (AH) and from mild fibrosis to cirrhosis. Fatty liver disease and steatohepatitis similarly occur in individuals who have both metabolic syndrome and excessive alcohol intake; therefore, the single overarching term metabolic associated fatty liver disease (MAFLD) has been proposed to better reflect these risk factors and the continuity of disease progression. Extracellular vesicles (EVs) are membrane-bound endogenous nanoparticles released into the extracellular space by a majority of cell types. Liver disease-related EVs contain a variety of cellular cargo and are internalized into target cells resulting in the transfer of bioinformation reflecting the state of the donor cell to the recipient. Furthermore, EV composition can be used to identify the degree and type of liver disease, suggesting that EV composition may be a useful biomarker. With regard to MAFLD, the presence of metabolic risk factors, such as insulin resistance, will be indicated by adipose tissue-derived EVs and with that comes the potential to use as a clinical monitor of overall metabolic status. However, the inhibition of specific EV composition may be difficult to implement as a real-world therapeutic approach. Current global evidence shows that mesenchymal stem cell (MSCs)-derived EVs (MSC-EVs) play an important role in regulating the immune response, which has spawned a clinical trial to treat liver disease.

Mechanisms of Action of Mesenchymal Stem Cells in Metabolic-Associated Fatty Liver Disease

Metabolic-associated fatty liver disease (MAFLD) is currently the most common chronic liver disease worldwide. However, its pathophysiological mechanism is complicated, and currently, it has no FDA-approved pharmacological therapies. In recent years, mesenchymal stem cell (MSC) therapy has attracted increasing attention in the treatment of hepatic diseases. MSCs are multipotent stromal cells that originated from mesoderm mesenchyme, which have self-renewal and multipotent differentiation capability. Recent experiments and studies have found that MSCs have the latent capacity to be used for MAFLD treatment. MSCs have the potential to differentiate into hepatocytes, which could be induced into hepatocyte-like cells (HLCs) with liver-specific morphology and function under appropriate conditions to promote liver tissue regeneration. They can also reduce liver tissue injury and reverse the development of MAFLD by regulating immune response, antifibrotic activities, and lipid metabolism. Moreover, several advantages are attributed to MSC-derived exosomes (MSC-exosomes), such as targeted delivery, reliable reparability, and poor immunogenicity. After entering the target cells, MSC-exosomes help regulate cell function and signal transduction; thus, it is expected to become an emerging treatment for MAFLD. In this review, we comprehensively discussed the roles of MSCs in MAFLD, main signaling pathways of MSCs that affect MAFLD, and mechanisms of MSC-exosomes on MAFLD.

Immunomodulatory role of mesenchymal stem cell therapy in liver fibrosis

Liver fibrosis is a fibrogenic and inflammatory process that results from hepatocyte injury and is characterized by hepatic architectural distortion and resultant loss of liver function. There is no effective treatment for advanced fibrosis other than liver transplantation, but it is limited by expensive costs, immune rejection, and postoperative complications. With the development of regenerative medicine in recent years, mesenchymal stem cell (MSCs) transplantation has become the most promising treatment for liver fibrosis. The underlying mechanisms of MSC anti-fibrotic effects include hepatocyte differentiation, paracrine, and immunomodulation, with immunomodulation playing a central role. This review discusses the immune cells involved in liver fibrosis, the immunomodulatory properties of MSCs, and the immunomodulation mechanisms of MSC-based strategies to attenuate liver fibrosis. Meanwhile, we discuss the current challenges and future directions as well.

Exosomes in liver fibrosis: The role of modulating hepatic stellate cells and immune cells, and prospects for clinical applications

Liver fibrosis is a global health problem caused by chronic liver injury resulting from various factors. Hepatic stellate cells (HSCs) have been found to play a major role in liver fibrosis, and pathological stimuli lead to their transdifferentiation into myofibroblasts. Complex multidirectional interactions between HSCs, immune cells, and cytokines are also critical for the progression of liver fibrosis. Despite the advances in treatments for liver fibrosis, they do not meet the current medical needs. Exosomes are extracellular vesicles of 30-150 nm in diameter and are capable of intercellular transport of molecules such as lipids, proteins and nucleic acids. As an essential mediator of intercellular communication, exosomes are involved in the physiological and pathological processes of many diseases. In liver fibrosis, exosomes are involved in the pathogenesis mainly by regulating the activation of HSCs and the interaction between HSCs and immune cells. Serum-derived exosomes are promising biomarkers of liver fibrosis. Exosomes also have promising therapeutic potential in liver fibrosis. Exosomes derived from mesenchymal stem cells and other cells exhibit anti-liver fibrosis effects. Moreover, exosomes may serve as potential therapeutic targets for liver fibrosis and hold promise in becoming drug carriers for liver fibrosis treatment.

Immunomodulatory potential of mesenchymal stem cell-derived extracellular vesicles: Targeting immune cells

Various intractable inflammatory diseases caused by disorders of immune systems have pressed heavily on public health. Innate and adaptive immune cells as well as secreted cytokines and chemokines are commanders to mediate our immune systems. Therefore, restoring normal immunomodulatory responses of immune cells is crucial for the treatment of inflammatory diseases. Mesenchymal stem cell derived extracellular vesicles (MSC-EVs) are nano-sized double-membraned vesicles acting as paracrine effectors of MSCs. MSC-EVs, containing a variety of therapeutic agents, have shown great potential in immune modulation. Herein, we discuss the novel regulatory functions of MSC-EVs from different sources in the activities of innate and adaptive immune cells like macrophages, granulocytes, mast cells, natural killer (NK) cells, dendritic cells (DCs) and lymphocytes. Then, we summarize the latest clinical trials of MSC-EVs in inflammatory diseases. Furthermore, we prospect the research trend of MSC-EVs in the field of immune modulation. Despite the fact that the research on the role of MSC-EVs in regulating immune cells is in infancy, this cell-free therapy based on MSC-EVs still offers a promising solution for the treatment of inflammatory diseases.

Current Therapeutic Options and Potential of Mesenchymal Stem Cell Therapy for Alcoholic Liver Disease

Alcoholic liver disease (ALD) is a globally prevalent chronic liver disease caused by chronic or binge consumption of alcohol. The therapeutic efficiency of current therapies for ALD is limited, and there is no FDA-approved therapy for ALD at present. Various strategies targeting pathogenic events in the progression of ALD are being investigated in preclinical and clinical trials. Recently, mesenchymal stem cells (MSCs) have emerged as a promising candidate for ALD treatment and have been tested in several clinical trials. MSC-released factors have captured attention, as they have the same therapeutic function as MSCs. Herein, we focus on current therapeutic options, recently proposed strategies, and their limitations in ALD treatment. Also, we review the therapeutic effects of MSCs and those of MSC-related secretory factors on ALD. Although accumulating evidence suggests the therapeutic potential of MSCs and related factors in ALD, the mechanisms underlying their actions in ALD have not been well studied. Further investigations of the detailed mechanisms underlying the therapeutic role of MSCs in ALD are required to expand MSC therapies to clinical applications. This review provides information on current or possible treatments for ALD and contributes to our understanding of the development of effective and safe treatments for ALD.

Therapeutic potential of mesenchymal stem cells in the treatment of acute liver failure

Acute liver failure (ALF) is a severe and life-threatening condition in which rapid deterioration of liver function develops in a patient who has no preexisting liver disease. Mesenchymal stem cells (MSCs) are immunoregulatory stem cells which are able to modulate phenotype and function of all immune cells that play pathogenic role in the development and progression of ALF. MSCs in juxtacrine and paracrine manner attenuate antigen-presenting properties of dendritic cells and macrophages, reduce production of inflammatory cytokines in T lymphocytes, suppress hepatotoxicity of natural killer T (NKT) cells and promote generation and expansion of immunosuppressive T, B and NKT regulatory cells in acutely inflamed liver. Due to their nano-sized dimension and lipid envelope, intravenously injected MSC-derived exosomes (MSC-Exos) may by-pass all biological barriers to deliver MSC-sourced immunoregulatoy factors directly into the liver-infiltrated immune cells and injured hepatocytes. Results obtained by us and others revealed that intravenous administration of MSCs and MSC-Exos efficiently attenuated detrimental immune response and acute inflammation in the liver, suggesting that MSCs and MSC-Exos could be considered as potentially new remedies in the immunotherapy of ALF. In this review, we emphasize the current knowledge about molecular and cellular mechanisms which are responsible for MSC-based modulation of liver-infiltrated immune cells and we discuss different insights regarding the therapeutic potential of MSCs in liver regeneration.

Preparation of Recombinant Human Collagen III Protein Hydrogels with Sustained Release of Extracellular Vesicles for Skin Wound Healing

Existing treatment methods encounter difficulties in effectively promoting skin wound healing, making this a serious challenge for clinical treatment. Extracellular vesicles (EVs) secreted by stem cells have been proven to contribute to the regeneration and repair of wound tissue, but they cannot be targeted and sustained, which seriously limits their current therapeutic potential. The recombinant human collagen III protein (rhCol III) has the advantages of good water solubility, an absence of hidden viral dangers, a low rejection rate and a stable production process. In order to achieve a site-specific sustained release of EVs, we prepared a rhCol III hydrogel by cross-linking with transglutaminase (TGase) from Streptomyces mobaraensis, which has a uniform pore size and good biocompatibility. The release profile of the rhCol III-EVs hydrogel confirmed that the rhCol III hydrogel could slowly release EVs into the external environment. Herein, the rhCol III-EVs hydrogel effectively promoted macrophage changing from type M1 to type M2, the migration ability of L929 cells and the angiogenesis of human umbilical vein endothelial cells (HUVECs). Furthermore, the rhCol III-EVs hydrogel is shown to promote wound healing by inhibiting the inflammatory response and promoting cell proliferation and angiogenesis in a diabetic rat skin injury model. The reported results indicate that the rhCol III-EVs hydrogel could be used as a new biological material for EV delivery, and has a significant application value in skin wound healing.