Exosomal miR-1246 derived from human umbilical cord blood mesenchymal stem cells attenuates hepatic ischemia reperfusion injury by modulating T helper 17/regulatory T balance

Therapeutic Efficacy and Promise of Human Umbilical Cord Mesenchymal Stem Cell-Derived Extracellular Vesicles in Aging and Age-Related Disorders

The global issue of aging populations has become increasingly prominent, thus the research and development for anti-aging therapies to assure longevity as well as to ameliorate age-related complications is put high on the agenda. The young humoral milieu has been substantiated to impart youthful characteristics to aged cells or organs. Extracellular vesicles (EVs) are a heterogeneous group of cell-derived membrane-limited structures that serve as couriers of proteins and genetic material to regulate intercellular communication. Of note, EVs appeared to be an indispensable component of young blood in prolonging lifespans, and circulating EVs have been indicated to mediate the beneficial effect of a young milieu on aging. Human umbilical cord mesenchymal stem cell-derived EVs (HUCMSC-EVs), isolated from the youngest adult stem cell source, are speculated to reproduce the function of circulating EVs in young blood and partially revitalize numerous organs in old animals. Robust evidence has suggested HUCMSC-EVs as muti-target therapeutic agents in combating aging and alleviating age-related degenerative disorders. Here, we provide a comprehensive overview of the anti-aging effects of HUCMSC-EVs in brain, heart, vasculature, kidney, muscle, bone, and other organs. Furthermore, we critically discuss the current investigation on engineering strategies of HUCMSC-EVs, intending to unveil their full potential in the field of anti-aging research.

Exosomal lncRNA TUG1 derived from BMSC ameliorate collagen-induced arthritis via BLIMP1-mediated Th17/Treg balance

BACKGROUND

Aberrant differentiation of Th17 cells has been identified as a critical factor in the development of rheumatoid arthritis (RA). BLIMP1 plays a key role in regulating plasma cell differentiation, T helper cell differentiation and Treg cell differentiation. Treatment with exosome injection or bone marrow mesenchymal stem cell (BMSC) transplantation reduce joint damage in RA. But the precise regulatory mechanisms remain unclear.

METHODS

We injected BMSC-derived exosomes into RA mice, and then performed histological analysis on mouse ankle joints. We cultured CD4+ T cells in vitro, then added exosomes with or without si-TUG1 and induced the differentiation of Th17 cells and Treg cells, and then we used flow cytometry to detect the ratio of Th17 cells and Treg cells. Furthermore, we injected exosomes into sh-NC or sh-BLIMP1-treated RA mice, and then performed histological analysis on the ankle joints.

RESULT

The results of our study demonstrate that exosome treatment decreased the proportion of differentiated Th17 cells, while increasing the proportion of Treg cells. And we observed that the Exo si-TUG1 group had an increased proportion of Th17 cells and a decreased proportion of Treg cells. We observed an increase in BLIMP1 expression in both the peripheral blood of mice and in CD4+ T cells cultured in vitro in the Exo group. Conversely, the Exo si-TUG1 group showed a decrease in BLIMP1 expression. Notably, inhibiting BLIMP1 expression led to the reversal of the therapeutic effects of exosomes.

CONCLUSION

Our findings suggest that BMSC-derived exosomes promote the expression of BLIMP1 through Lnc TUG1-carrying exosomes, which may modulate the balance between Th17 cells and Treg cells. This mechanism ultimately alleviates damage caused by RA, suggesting that BMSC-derived exosomes enriched in Lnc TUG1 hold promise as a potential therapeutic approach for treating RA.

Therapeutic Potential of Stem Cell-Derived Extracellular Vesicles in Liver Injury

Liver injury caused by various factors significantly impacts human health. Stem cell transplantation has potential for enhancing liver functionality, but safety concerns such as immune rejection, tumorigenesis, and the formation of emboli in the lungs remain. Recent studies have shown that stem cells primarily exert their effects through the secretion of extracellular vesicles (EVs). EVs have been shown to play crucial roles in reducing inflammation, preventing cell death, and promoting liver cell proliferation. Additionally, they can function as carriers to deliver targeted drugs to the liver, thereby exerting specific physiological effects. EVs possess several advantages, including structural stability, low immunogenicity, minimal tumorigenicity targeting capabilities, and convenient collection. Consequently, EVs have garnered significant attention from researchers and are expected to become alternative therapeutic agents to stem cell therapy. This article provides a comprehensive review of the current research progress in the use of stem cell-derived EVs in the treatment of liver injury.

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.

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.

Understanding exosomes: Part 2-Emerging leaders in regenerative medicine

Exosomes are the smallest subset of extracellular signaling vesicles secreted by most cells with the ability to communicate with other tissues and cell types over long distances. Their use in regenerative medicine has gained tremendous momentum recently due to their ability to be utilized as therapeutic options for a wide array of diseases/conditions. Over 5000 publications are currently being published yearly on this topic, and this number is only expected to dramatically increase as novel therapeutic strategies continue to be developed. Today exosomes have been applied in numerous contexts including neurodegenerative disorders (Alzheimer's disease, central nervous system, depression, multiple sclerosis, Parkinson's disease, post-traumatic stress disorders, traumatic brain injury, peripheral nerve injury), damaged organs (heart, kidney, liver, stroke, myocardial infarctions, myocardial infarctions, ovaries), degenerative processes (atherosclerosis, diabetes, hematology disorders, musculoskeletal degeneration, osteoradionecrosis, respiratory disease), infectious diseases (COVID-19, hepatitis), regenerative procedures (antiaging, bone regeneration, cartilage/joint regeneration, osteoarthritis, cutaneous wounds, dental regeneration, dermatology/skin regeneration, erectile dysfunction, hair regrowth, intervertebral disc repair, spinal cord injury, vascular regeneration), and cancer therapy (breast, colorectal, gastric cancer and osteosarcomas), immune function (allergy, autoimmune disorders, immune regulation, inflammatory diseases, lupus, rheumatoid arthritis). This scoping review is a first of its kind aimed at summarizing the extensive regenerative potential of exosomes over a broad range of diseases and disorders.

The role of miRNAs in T helper cell development, activation, fate decisions and tumor immunity

T helper (Th) cells are central members of adaptive immunity and comprise the last line of defense against pathogen infection and malignant cell invasion by secreting specific cytokines. These cytokines then attract or induce the activation and differentiation of other immune cells, including antibody-producing B cells and cytotoxic CD8+ T cells. Therefore, the bidirectional communication between Th cells and tumor cells and their positioning within the tumor microenvironment (TME), especially the tumor immune microenvironment (TIME), sculpt the tumor immune landscape, which affects disease initiation and progression. The type, number, and condition of Th cells in the TME and TIME strongly affect tumor immunity, which is precisely regulated by key effectors, such as granzymes, perforins, cytokines, and chemokines. Moreover, microRNAs (miRNAs) have emerged as important regulators of Th cells. In this review, we discuss the role of miRNAs in regulating Th cell mediated adaptive immunity, focusing on the development, activation, fate decisions, and tumor immunity.

Pathological and therapeutic effects of extracellular vesicles in neurological and neurodegenerative diseases

Extracellular vesicles are released by all cell types and contain proteins, microRNAs, mRNAs, and other bioactive molecules. Extracellular vesicles play an important role in intercellular communication and in the modulation of the immune system and neuroinflammation. The cargo of extracellular vesicles (e.g., proteins and microRNAs) is altered in pathological situations. Extracellular vesicles contribute to the pathogenesis of many pathologies associated with sustained inflammation and neuroinflammation, including cancer, diabetes, hyperammonemia and hepatic encephalopathy, and other neurological and neurodegenerative diseases. Extracellular vesicles may cross the blood-brain barrier and transfer pathological signals from the periphery to the brain. This contributes to inducing neuroinflammation and cognitive and motor impairment in hyperammonemia and hepatic encephalopathy and in neurodegenerative diseases. The mechanisms involved are beginning to be understood. For example, increased tumor necrosis factor α in extracellular vesicles from plasma of hyperammonemic rats induces neuroinflammation and motor impairment when injected into normal rats. Identifying the mechanisms by which extracellular vesicles contribute to the pathogenesis of these diseases will help to develop new treatments and diagnostic tools for their easy and early detection. In contrast, extracellular vesicles from mesenchymal stem cells have therapeutic utility in many of the above pathologies, by reducing inflammation and neuroinflammation and improving cognitive and motor function. These extracellular vesicles recapitulate the beneficial effects of mesenchymal stem cells and have advantages as therapeutic tools: they are less immunogenic, may not differentiate to malignant cells, cross the blood-brain barrier, and may reach more easily target organs. Extracellular vesicles from mesenchymal stem cells have beneficial effects in models of ischemic brain injury, Alzheimer's and Parkinson's diseases, hyperammonemia, and hepatic encephalopathy. Extracellular vesicles from mesenchymal stem cells modulate the immune system, promoting the shift from a pro-inflammatory to an anti-inflammatory state. For example, extracellular vesicles from mesenchymal stem cells modulate the Th17/Treg balance, promoting the anti-inflammatory Treg. Extracellular vesicles from mesenchymal stem cells may also act directly in the brain to modulate microglia activation, promoting a shift from a pro-inflammatory to an anti-inflammatory state. This reduces neuroinflammation and improves cognitive and motor function. Two main components of extracellular vesicles from mesenchymal stem cells which contribute to these beneficial effects are transforming growth factor-β and miR-124. Identifying the mechanisms by which extracellular vesicles from mesenchymal stem cells induce the beneficial effects and the main molecules (e.g., proteins and mRNAs) involved may help to improve their therapeutic utility. The aims of this review are to summarize the knowledge of the pathological effects of extracellular vesicles in different pathologies, the therapeutic potential of extracellular vesicles from mesenchymal stem cells to recover cognitive and motor function and the molecular mechanisms for these beneficial effects on neurological function.

Strategies to improve the therapeutic efficacy of mesenchymal stem cell-derived extracellular vesicle (MSC-EV): a promising cell-free therapy for liver disease

Liver disease has emerged as a significant worldwide health challenge due to its diverse causative factors and therapeutic complexities. The majority of liver diseases ultimately progress to end-stage liver disease and liver transplantation remains the only effective therapy with the limitations of donor organ shortage, lifelong immunosuppressants and expensive treatment costs. Numerous pre-clinical studies have revealed that extracellular vesicles released by mesenchymal stem cells (MSC-EV) exhibited considerable potential in treating liver diseases. Although natural MSC-EV has many potential advantages, some characteristics of MSC-EV, such as heterogeneity, uneven therapeutic effect, and rapid clearance in vivo constrain its clinical translation. In recent years, researchers have explored plenty of ways to improve the therapeutic efficacy and rotation rate of MSC-EV in the treatment of liver disease. In this review, we summarized current strategies to enhance the therapeutic potency of MSC-EV, mainly including optimization culture conditions in MSC or modifications of MSC-EV, aiming to facilitate the development and clinical application of MSC-EV in treating liver disease.

Innovative preconditioning strategies for improving the therapeutic efficacy of extracellular vesicles derived from mesenchymal stem cells in gastrointestinal diseases

Gastrointestinal (GI) diseases have become a global health issue and an economic burden due to their wide distribution, late prognosis, and the inefficacy of recent available medications. Therefore, it is crucial to search for new strategies for their management. In the recent decades, mesenchymal stem cells (MSCs) therapy has attracted attention as a viable option for treating a myriad of GI disorders such as hepatic fibrosis (HF), ulcerative colitis (UC), acute liver injury (ALI), and non-alcoholic fatty liver disease (NAFLD) due to their regenerative and paracrine properties. Importantly, recent studies have shown that MSC-derived extracellular vesicles (MSC-EVs) are responsible for most of the therapeutic effects of MSCs. In addition, EVs have revealed several benefits over their parent MSCs, such as being less immunogenic, having a lower risk of tumour formation, being able to cross biological barriers, and being easier to store. MSC-EVs exhibited regenerative, anti-oxidant, anti-inflammatory, anti-apoptotic, and anti-fibrotic effects in different experimental models of GI diseases. However, a key issue with their clinical application is the maintenance of their stability and efficacy following in vivo transplantation. Preconditioning of MSC-EVs or their parent cells is one of the novel methods used to improve their effectiveness and stability. Herein, we discuss the application of MSC-EVs in several GI disorders taking into account their mechanism of action. We also summarise the challenges and restrictions that need to be overcome to promote their clinical application in the treatment of various GI diseases as well as the recent developments to improve their effectiveness. A representation of the innovative preconditioning techniques that have been suggested for improving the therapeutic efficacy of MSC-EVs in GI diseases. The pathological conditions in various GI disorders (ALI, UC, HF and NAFLD) create a harsh environment for EVs and their parents, increasing the risk of apoptosis and senescence of MSCs and thereby diminishing MSC-EVs yield and restricting their large-scale applications. Preconditioning with pharmacological agents or biological mediators can improve the therapeutic efficacy of MSC-EVs through their adaption to the lethal environment to which they are subjected. This can result in establishment of a more conducive environment and activation of numerous vital trajectories that act to improve the immunomodulatory, reparative and regenerative activities of the derived EVs, as a part of MSCs paracrine system. ALI, acute liver injury; GI diseases, gastrointestinal diseases; HF, hepatic fibrosis; HSP, heat shock protein; miRNA, microRNA; mRNA, messenger RNA; MSC-EVs, mesenchymal stem cell-derived extracellular vesicles; NAFLD, non-alcoholic fatty liver disease; UC, ulcerative colitis.

Stem cell Derived Extracellular Vesicles to Alleviate ischemia-reperfusion Injury of Transplantable Organs. A Systematic Review

BACKGROUND

The possible beneficial effects of stem cell-derived EV on ischemia-reperfusion injury (IRI) in organ transplantation have been frequently investigated; however, the source of EV, as well as the methods of isolation and administration vary widely. We conducted a systematic review to summarize current pre-clinical evidence on stem cell-derived EV therapy for IRI of transplantable organs.

METHODS

PubMed, Embase and Web of Science were searched from inception until August 19th, 2022, for studies on stem cell-derived EV therapy for IRI after heart, kidney, liver, pancreas, lung and intestine transplantation. The Systematic Review Center for Laboratory animal Experiments (SYRCLE) guidelines were followed to assess potential risk of bias.

RESULTS

The search yielded 4153 unique articles, of which 96 were retained. We identified 32 studies on cardiac IRI, 38 studies on renal IRI, 21 studies on liver IRI, four studies on lung IRI and one study on intestinal IRI. Most studies used rodent models of transient ischemic injury followed by in situ reperfusion. In all studies, EV therapy was associated with improved outcome albeit to a variable degree. EV-therapy reduced organ injury and improved function while displaying anti-inflammatory-, immunomodulatory- and pro-regenerative properties.

CONCLUSION

A multitude of animal studies support the potential of stem cell-derived EV-therapy to alleviate IRI after solid organ transplantation but suffer from low reporting quality and wide methodological variability. Future studies should focus on determining optimal stem cell source, dosage, and timing of treatment, as well as long-term efficacy in transplant models.

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.

Current Status and Prospect of Delivery Vehicle Based on Mesenchymal Stem Cell-Derived Exosomes in Liver Diseases

With the improvement of the average life expectancy and increasing incidence of obesity, the burden of liver disease is increasing. Liver disease is a serious threat to human health. Currently, liver transplantation is the only effective treatment for end-stage liver disease. However, liver transplantation still faces unavoidable difficulties. Mesenchymal stem cells (MSCs) can be used as an alternative therapy for liver disease, especially liver cirrhosis, liver failure, and liver transplantation complications. However, MSCs may have potential tumorigenic effects. Exosomes derived from MSCs (MSC-Exos), as the important intercellular communication mode of MSCs, contain various proteins, nucleic acids, and DNA. MSC-Exos can be used as a delivery system to treat liver diseases through immune regulation, apoptosis inhibition, regeneration promotion, drug delivery, and other ways. Good histocompatibility and material exchangeability make MSC-Exos a new treatment for liver diseases. This review summarizes the latest research on MSC-Exos as delivery vehicles in different liver diseases, including liver injury, liver failure, liver fibrosis, hepatocellular carcinoma (HCC), and ischemia and reperfusion injury. In addition, we discuss the advantages, disadvantages, and clinical application prospects of MSC-Exos-based delivery vectors in the treatment of liver diseases.

Umbilical cord blood exosomes from very preterm infants with bronchopulmonary dysplasia aggravate lung injury in mice

Bronchopulmonary dysplasia (BPD) is characterized by abnormal development of the blood vessels and alveoli in lungs, which largely occurs in premature infants. Exosomes (EXO) from very preterm infants (VPI) with BPD (BPD-EXO) impair angiogenic activities of human umbilical vein endothelial cells (HUVECs) via EXO-miRNAs cargo. This study aimed to determine whether and how BPD-EXO affect the development of BPD in a mouse model. We showed that treating BPD mice with BPD-EXO chronically and irreversibly aggravated lung injury. BPD-EXO up-regulated 139 and down-regulated 735 genes in the mouse lung tissue. These differentially expressed genes were enriched to the MAPK pathway (e.g., Fgf9 and Cacna2d3), which is critical to angiogenesis and vascular remodeling. BPD-EXO suppressed expression of Fgf9 and Cacna2d3 in HUVECs and inhibited migration, tube formation, and increased cell apoptosis in HUVECs. These data demonstrate that BPD-EXO aggravate lung injury in BPD mice and impair lung angiogenesis, plausibly leading to adverse outcomes of VPI with BPD. These data also suggest that BPD-EXO could serve as promising targets for predicting and treating BPD.

miRNA-Guided Regulation of Mesenchymal Stem Cells Derived from the Umbilical Cord: Paving the Way for Stem-Cell Based Regeneration and Therapy

The human body is an abundant source of multipotent cells primed with unique properties that can be exploited in a multitude of applications and interventions. Mesenchymal stem cells (MSCs) represent a heterogenous population of undifferentiated cells programmed to self-renew and, depending on their origin, differentiate into distinct lineages. Alongside their proven ability to transmigrate toward inflammation sites, the secretion of various factors that participate in tissue regeneration and their immunoregulatory function render MSCs attractive candidates for use in the cytotherapy of a wide spectrum of diseases and conditions, as well as in different aspects of regenerative medicine. In particular, MSCs that can be found in fetal, perinatal, or neonatal tissues possess additional capabilities, including predominant proliferation potential, increased responsiveness to environmental stimuli, and hypoimmunogenicity. Since microRNA (miRNA)-guided gene regulation governs multiple cellular functions, miRNAs are increasingly being studied in the context of driving the differentiation process of MSCs. In the present review, we explore the mechanisms of miRNA-directed differentiation of MSCs, with a special focus on umbilical cord-derived mesenchymal stem cells (UCMSCs), and we identify the most relevant miRNAs and miRNA sets and signatures. Overall, we discuss the potent exploitations of miRNA-driven multi-lineage differentiation and regulation of UCMSCs in regenerative and therapeutic protocols against a range of diseases and/or injuries that will achieve a meaningful clinical impact through maximizing treatment success rates, while lacking severe adverse events.

Human umbilical cord mesenchymal stem cells-derived exosomal circDLGAP4 promotes angiogenesis after cerebral ischemia-reperfusion injury by regulating miR-320/KLF5 axis

Accumulating evidence suggests that human umbilical cord mesenchymal stem cell-derived exosomes (hUC-MSCs-Exos) are a promising therapeutic strategy for cerebral ischemia-reperfusion injury (CIRI). However, the underlying mechanism remains unclear. hUC-MSCs-Exos were identified by electron microscopy, NTA, and Western blotting. In the hypoxia/reoxygenation (H/R) cell model, human brain microvascular endothelial cells (HBMECs) were cocultured with hUC-MSCs-Exos. Then, cell viability, migration, apoptosis, and tube formation were measured by MTT, flow cytometry, transwell, and tube formation assays. RT-qPCR and Western blotting were used to detect the changes in RNA and protein. RNA pull-down and dual luciferase reporter assays confirmed the relationship between circDLGAP4, miR-320, and KLF5. Ischemia-reperfusion (I/R) rat model was established for in vivo experiments. hUC-MSCs-Exos increased the expression levels of circDLGAP4 and KLF5 but decreased miR-320 in H/R-treated HBMECs by transferring exosomal circDLGAP4. Knockdown of circDLGAP4 in hUC-MSCs-Exos reversed the promoting effects of hUC-MSCs-Exos on cell viability, migration, and tube formation in H/R-treated HBMECs in vitro and also abolished the protective effects of hUC-MSCs-Exos on cerebrovascular injury in I/R rats. Mechanistically, exosomal circDLGAP4 negatively regulated miR-320 in HBMECs, which directly bound to KLF5. In addition, the downregulation of miR-320 could reverse the regulatory effect of exosomal shcircDLGAL5 in H/R-treated HBMECs by upregulating KLF5. hUC-MSCs-Exos-derived circDLGAP4 reduced cerebrovascular injury by regulating miR-320/KLF5 signaling. These results provide a stem cell-based approach to treat CIRI.

Role of Mesenchymal Stem/Stromal Cells in Modulating Ischemia/Reperfusion Injury: Current State of the Art and Future Perspectives

Ischemia/reperfusion injury (IRI) is a multistep damage that occurs in several tissues when a blood flow interruption is inevitable, such as during organ surgery or transplantation. It is responsible for cell death and tissue dysfunction, thus leading, in the case of transplantation, to organ rejection. IRI takes place during reperfusion, i.e., when blood flow is restored, by activating inflammation and reactive oxygen species (ROS) production, causing mitochondrial damage and apoptosis of parenchymal cells. Unfortunately, none of the therapies currently in use are definitive, prompting the need for new therapeutic approaches. Scientific evidence has proven that mesenchymal stem/stromal cells (MSCs) can reduce inflammation and ROS, prompting this cellular therapy to also be investigated for treatment of IRI. Moreover, it has been shown that MSC therapeutic effects were mediated in part by their secretome, which appears to be involved in immune regulation and tissue repair. For these reasons, mediated MSC paracrine function might be key for injury amelioration upon IRI damage. In this review, we highlight the scientific literature on the potential beneficial use of MSCs and their products for improving IRI outcomes in different tissues/organs, focusing in particular on the paracrine effects mediated by MSCs, and on the molecular mechanisms behind these effects.

Research progress of lncRNA and miRNA in hepatic ischemia-reperfusion injury

BACKGROUND

Hepatic ischemia-reperfusion injury (HIRI) is a common complication of liver surgeries, such as hepatectomy and liver transplantation. In recent years, several non-coding RNAs (ncRNAs) including long non-coding RNAs (lncRNAs) and microRNAs (miRNAs) have been identified as factors involved in the pathological progression of HIRI. In this review, we summarized the latest research on lncRNAs, miRNAs and the lncRNA-miRNA regulatory networks in HIRI.

DATA SOURCES

The PubMed and Web of Science databases were searched for articles published up to December 2021 using the following keywords: "hepatic ischemia-reperfusion injury", "lncRNA", "long non-coding RNA", "miRNA" and "microRNA". The bibliography of the selected articles was manually screened to identify additional studies.

RESULTS

The mechanism of HIRI is complex, and involves multiple lncRNAs and miRNAs. The roles of lncRNAs such as AK139328, CCAT1, MALAT1, TUG1 and NEAT1 have been established in HIRI. In addition, numerous miRNAs are associated with apoptosis, autophagy, oxidative stress and cellular inflammation that accompany HIRI pathogenesis. Based on the literature, we conclude that four lncRNA-miRNA regulatory networks mediate the pathological progression of HIRI. Furthermore, the expression levels of some lncRNAs and miRNAs undergo significant changes during the progression of HIRI, and thus are potential prognostic markers and therapeutic targets.

CONCLUSIONS

Complex lncRNA-miRNA-mRNA networks regulate HIRI progression through mutual activation and antagonism. It is necessary to screen for more HIRI-associated lncRNAs and miRNAs in order to identify novel therapeutic targets.

MicroRNA-1246 Inhibits NFATc1 Phosphorylation and Regulates T Helper 17 Cell Activation in the Pathogenesis of Severe Alopecia Areata

BACKGROUND

We found microRNA (miR)-1246 to be significantly differentially expressed between severe active alopecia areata (AA) patients and healthy individuals.

OBJECTIVE

To explore the role and mechanism of miR-1246 in severe AA.

METHODS

Expression of miR-1246, dual-specific tyrosine phosphorylation-regulated kinase 1A (DYRK1A), and nuclear factor of activated T cells 1c (NFATc1) in peripheral CD4⁺ T cells and in scalp tissues of patients were detected using RT-qPCR, Western blot, and immunohistochemistry assays. Peripheral CD4⁺ T cells from the AA patients were transfected with lentiviral vectors overexpressing miR-1246. RT-qPCR and Western blot analysis were used to measure mRNA or protein expression of retinoic-acid-receptor-related orphan nuclear receptor gamma (ROR-γt), interleukin (IL)-17, DYRK1A, NFATc1, and phosphorylated NFATc1. Flow cytometry was used to assay the CD4⁺IL-17⁺ cells proportion. ELISA was used to measure cytokine levels.

RESULTS

miR-1246 levels decreased and DYRK1A and NFATc1 mRNA levels significantly increased in the peripheral CD4⁺ T cells and scalp tissues of severe active AA samples. NFATc1 protein expression was also significantly increased in the peripheral CD4⁺ T cells but not in the scalp tissues. NFATc1 positive cells were mainly distributed among infiltrating inflammatory cells around hair follicles. In peripheral CD4⁺ T cells of severe active AA, overexpression of miR-1246 resulted in significant downregulation of DYRK1A, NFATc1, ROR-γt, and IL-17 mRNA and phosphorylated NFATc1 protein, as well as a decrease in the CD4⁺IL-17⁺ cells proportion and the IL-17F level.

CONCLUSION

miR-1246 can inhibit NFAT signaling and Th17 cell activation, which may be beneficial in the severe AA treatment.

The research development of STAT3 in hepatic ischemia-reperfusion injury

Ischemia-reperfusion injury (IRI) is a common complication of surgery, which can cause rapid deterioration of the liver function, increase the risk of graft rejection, and seriously affect the prognosis of patients. The signal transducer and activator of transcription 3 (STAT3) protein has been implicated in pathogenesis of IRI. STAT3 influences the mitochondria through multiple pathways and is also involved in apoptosis and other forms of programmed cell death. STAT3 is associated with Janus kinase (JAK), phosphoinositide-3 kinase (PI3K), and heme oxygenase-1 (HO-1) in liver IRI. The STAT3 pathway plays a dual role in IRI as it can also regulate lipid metabolism which may have potential for treating IRI fatty liver. In this review, we summarize research on the function of STAT3 in liver IRI to provide references for its application in the clinic.

Breast cancer tumor microenvironment affects Treg/IL-17-producing Treg/Th17 cell axis: Molecular and therapeutic perspectives

The tumor microenvironment (TME) comprises a variety of immune cells, among which T cells exert a prominent axial role in tumor development or anti-tumor responses in patients with breast cancer (BC). High or low levels of anti-inflammatory cytokines, such as transforming growth factor β, in the absence or presence of proinflammatory cytokines, such as interleukin-6 (IL-6), delineate the fate of T cells toward either regulatory T (Treg) or T helper 17 (Th17) cells, respectively. The transitional state of RORγt⁺Foxp3⁺ Treg (IL-17-producing Treg) resides in the middle of this reciprocal polarization, which is known as Treg/IL-17-producing Treg/Th17 cell axis. TME secretome, including microRNAs, cytokines, and extracellular vesicles, can significantly affect this axis. Furthermore, immune checkpoint inhibitors may be used to reconstruct immune cells; however, some of these novel therapies may favor tumor development. Therefore, understanding secretory and cell-associated factors involved in their differentiation or polarization and functions may be targeted for BC management. This review discusses microRNAs, cytokines, and extracellular vesicles (as secretome), as well as transcription factors and immune checkpoints (as cell-associated factors), which influence the Treg/IL-17-producing Treg/Th17 cell axis in BC. Furthermore, approved or ongoing clinical trials related to the modulation of this axis in the TME of BC are described to broaden new horizons of promising therapeutic approaches.

Exosomal miR-205-5p derived from periodontal ligament stem cells attenuates the inflammation of chronic periodontitis via targeting XBP1

INTRODUCTION

Chronic periodontitis (CP) is an inflammatory periodontal disease with high incidence and complex pathology. This research is aimed to investigate the function of exosomal miR-205-5p (Exo-miR-205-5p) in CP and the underlying molecular mechanisms.

METHOD

Exo-miR-205-5p was isolated from miR-205-5p mimics-transfected periodontal ligament stem cells (PDLSCs), and subsequently cocultured with lipopolysaccharide (LPS)-induced cells or injected into LPS-treated rats. The mRNA expression of inflammatory factors and Th17/Treg-related factors were measured by quantitative real-time PCR. The contents of inflammatory factors and the percentages of Th17/Treg cells were measured by enzyme-linked immunosorbent assay and flow cytometry, respectively. Besides, the target relation between miR-205-5p and X-box binding protein 1 (XBP1) was explored.

RESULTS

MiR-205-5p was downregulated in LPS-induced PDLSCs and corresponding exosomes. Exo-miR-205-5p inhibited inflammatory cell infiltration, decreased the production of TNF-α, IL-1β, and IL-6, and decreased the percentage of Th17 cells in LPS-treated rats. In addition, XBP1 was a target of miR-205-5p. Overexpression of XBP1 weakened the effects of Exo-miR-205-5p on inhibiting inflammation and regulating Treg/Th17 balance in LPS-induced cells.

CONCLUSIONS

Exo-miR-205-5p derived from PDLSCs relieves the inflammation and balances the Th17/Treg cells in CP through targeting XBP1.

Extracellular vesicles as potential biomarkers and treatment options for liver failure: A systematic review up to March 2022

Introduction

Extracellular vesicles (EVs) carrying functional cargoes are emerging as biomarkers and treatment strategies in multiple liver diseases. Nevertheless, the potential of EVs in liver failure remains indistinct. In this systematic review, we comprehensively analyzed the potential of EVs as biomarkers of liver failure and the therapeutic effects and possible mechanisms of EVs for liver failure.

Methods

We conducted a systematic review by comprehensively searching the following electronic databases: PubMed, Web of Science, Embase and Cochrane Central Register of Controlled Trials from inception to March 2022. The used text words (synonyms and word variations) and database-specific subject headings included "Extracellular Vesicles", "Exosomes", "Liver Failure", "Liver Injury", etc.

Results

A total of 1479 studies were identified. After removing 680 duplicate studies and 742 irrelevant studies, 57 studies were finally retained and analyzed. Fourteen studies revealed EVs with functional cargoes could be used to make the diagnosis of liver failure and provide clues for early warning and prognostic assessment of patients with liver failure. Forty-three studies confirmed the administration of EVs from different sources alleviated hepatic damage and improved survival through inhibiting inflammatory response, oxidative stress as well as apoptosis or promoting hepatocyte regeneration and autophagy.

Conclusions

EVs and their cargoes can be used not only as superior biomarkers of early warning, early diagnosis and prognostic assessments for liver failure, but also as potentially effective treatment options for liver failure. In the future, large-scale studies are urgently needed to verify the diagnostic, predictive and therapeutic value of EVs for liver failure.

Mesenchymal stem cell-derived exosomes and non-coding RNAs: Regulatory and therapeutic role in liver diseases

Liver disease has become a major health problem worldwide due to its high morbidity and mortality. In recent years, a large body of literature has shown that mesenchymal stem cell-derived exosomes (MSC-Exo) are able to play similar physiological roles as mesenchymal stem cells (MSCs). More importantly, there is no immune rejection caused by transplanted cells and the risk of tumor formation, which has become a new strategy for the treatment of various liver diseases. Moreover, accumulating evidence suggests that non-coding RNAs (ncRNAs) are the main effectors by which they exert hepatoprotective effects. Therefore, by searching the databases of Web of Science, PubMed, ScienceDirect, Google Scholar and CNKI, this review comprehensively reviewed the therapeutic effects of MSC-Exo and ncRNAs in liver diseases, including liver injury, liver fibrosis, and hepatocellular carcinoma. According to the data, the therapeutic effects of MSC-Exo and ncRNAs on liver diseases are closely related to a variety of molecular mechanisms, including inhibition of inflammatory response, alleviation of liver oxidative stress, inhibition of apoptosis of hepatocytes and endothelial cells, promotion of angiogenesis, blocking the cell cycle of hepatocellular carcinoma, and inhibition of activation and proliferation of hepatic stellate cells. These important findings will provide a direction and basis for us to explore the potential of MSC-Exo and ncRNAs in the clinical treatment of liver diseases in the future.

FOXO1 Alleviates Liver Ischemia-reperfusion Injury by Regulating the Th17/Treg Ratio through the AKT/Stat3/FOXO1 Pathway

Background and Aims

Hepatic ischemic reperfusion injury (IRI) occurring during surgery seriously affects patient prognosis. The specific mechanism of IRI has not been fully elucidated. The study aim was to explore the changes of inflammatory environment, and the relationship of the Th17/Treg cell ratio and FOXO1 expression in hepatic IRI.

Methods

Liver samples at different ischemic times were collected from patients and mice. The expression of inflammatory markers and FOXO1 in the liver was detected by western blotting and qPCR. Phenotypic changes of liver lymphocytes were analyzed by flow cytometry. The AKT/Stat3/FOXO1 pathway was verified by targeting AKT with GSK2141795. The role of FOXO1 in liver inflammation and changes in lymphocyte phenotype was confirmed by upregulating FOXO1 with resveratrol.

Results

Prolonged ischemic time aggravates liver injury in both humans and mouse models of hepatic IRI. IR-stress caused Th17/Treg imbalance and FOXO1 down-regulation by activating the AKT/Stat3/FOXO1 signaling pathway. Upregulation of FOXO1 reversed the Th17/Treg cytokine imbalance and altered the inflammation environment in the liver.

Conclusions

Liver IRI induced Th17/Treg imbalance. Upregulation of FOXO1 reversed the imbalance and alleviated liver inflammation.

Nucleic acids and proteins carried by exosomes from various sources: Potential role in liver diseases

Exosomes are extracellular membrane-encapsulated vesicles that are released into the extracellular space or biological fluids by many cell types through exocytosis. As a newly identified form of intercellular signal communication, exosomes mediate various pathological and physiological processes by exchanging various active substances between cells. The incidence and mortality of liver diseases is increasing worldwide. Therefore, we reviewed recent studies evaluating the role of exosomes from various sources in the diagnosis and treatment of liver diseases.

Mesenchymal Stem Cell-Derived Exosomes: A Promising Therapeutic Agent for the Treatment of Liver Diseases

Liver disease has become a major global health and economic burden due to its broad spectrum of diseases, multiple causes and difficult treatment. Most liver diseases progress to end-stage liver disease, which has a large amount of matrix deposition that makes it difficult for the liver and hepatocytes to regenerate. Liver transplantation is the only treatment for end-stage liver disease, but the shortage of suitable organs, expensive treatment costs and surgical complications greatly reduce patient survival rates. Therefore, there is an urgent need for an effective treatment modality. Cell-free therapy has become a research hotspot in the field of regenerative medicine. Mesenchymal stem cell (MSC)-derived exosomes have regulatory properties and transport functional "cargo" through physiological barriers to target cells to exert communication and regulatory activities. These exosomes also have little tumorigenic risk. MSC-derived exosomes promote hepatocyte proliferation and repair damaged liver tissue by participating in intercellular communication and regulating signal transduction, which supports their promise as a new strategy for the treatment of liver diseases. This paper reviews the physiological functions of exosomes and highlights the physiological changes and alterations in signaling pathways related to MSC-derived exosomes for the treatment of liver diseases in some relevant clinical studies. We also summarize the advantages of exosomes as drug delivery vehicles and discuss the challenges of exosome treatment of liver diseases in the future.

Breast cancer extracellular vesicles-derived miR-1290 activates astrocytes in the brain metastatic microenvironment via the FOXA2→CNTF axis to promote progression of brain metastases

Mechanisms underlying breast cancer brain metastasis (BCBM) are still unclear. In this study, we observed that extracellular vesicles (EVs) secreted from breast cancer cells with increased expression of tGLI1, a BCBM-promoting transcription factor, strongly activated astrocytes. EV-derived microRNA/miRNA microarray revealed tGLI1-positive breast cancer cells highly secreted miR-1290 and miR-1246 encapsulated in EVs. Genetic knockin/knockout studies established a direct link between tGLI1 and both miRNAs. Datamining and analysis of patient samples revealed that BCBM patients had more circulating EV-miRs-1290/1246 than those without metastasis. Ectopic expression of miR-1290 or miR-1246 strongly activated astrocytes whereas their inhibitors abrogated the effect. Conditioned media from miR-1290- or miR-1246-overexpressing astrocytes promoted mammospheres. Furthermore, miRs-1290/1246 suppressed expression of FOXA2 transcription repressor, leading to CNTF cytokine secretion and subsequent activation of astrocytes. Finally, we conducted a mouse study to demonstrate that astrocytes overexpressing miR-1290, but not miR-1246, enhanced intracranial colonization and growth of breast cancer cells. Collectively, our findings demonstrate, for the first time, that breast cancer EV-derived miR-1290 and miR-1246 activate astrocytes in the brain metastatic microenvironment and that EV-derived miR-1290 promotes progression of brain metastases through the novel EV-miR-1290→FOXA2→CNTF signaling axis.

Regulatory T cells and their associated factors in hepatocellular carcinoma development and therapy

Liver cancer is the third leading cause of cancer-related death worldwide with primary type hepatocellular carcinoma (HCC). Factors, including carcinogens, infection of hepatitis viruses, alcohol abuse, and non-alcoholic fatty liver disease (NAFLD), can induce HCC initiation and promote HCC progression. The prevalence of NAFLD accompanying the increased incidence of obesity and type 2 diabetes becomes the most increasing factor causing HCC worldwide. However, the benefit of current therapeutic options is still limited. Intrahepatic immunity plays critically important roles in HCC initiation, development, and progression. Regulatory T cells (Tregs) and their associated factors such as metabolites and secreting cytokines mediate the immune tolerance of the tumor microenvironment in HCC. Therefore, targeting Tregs and blocking their mediated factors may prevent HCC progression. This review summarizes the functions of Tregs in HCC-inducing factors including alcoholic and NAFLD, liver fibrosis, cirrhosis, and viral infections. Overall, a better understanding of the role of Tregs in the development and progression of HCC provides treatment strategies for liver cancer treatment.

Extracellular Vesicles From Kidney Allografts Express miR-218-5p and Alter Th17/Treg Ratios

Delayed graft function (DGF) in kidney transplantation is associated with ischemic injury and carries long term functional and immunological risks. Extracellular vesicles (EV) released from allografts may signal a degree of ischemic stress, and are thought to play an important role in the development of anti-donor immunity. Here, we show that kidney perfusate-derived extracellular vesicles (KP-EV) express donor-specific human leukocyte antigen. KP-EV from kidneys that experience DGF increase the T-helper 17 (Th17) to T-regulatory (Treg) ratio in third party peripheral blood mononuclear cells to a greater degree than those from kidneys with immediate function. We report miR-218-5p upregulation in KP-EV of kidney transplant recipients with DGF. Levels of miR-218-5p in KP-EV inversely correlated with recipient eGFR at multiple time points following transplantation. Additionally, the degree of increase in Th17/Treg ratio by KP-EV positively correlated with miR-218-5p expression in KP-EV samples. Taken together, these data provide evidence that KP-EV may contribute to modulating immune responses in transplant recipients. This could lead to novel intervention strategies to inhibit DGF in order to improve graft function and survival.

Mesenchymal stem cell-derived extracellular vesicles for cell-free therapy of ocular diseases

Mesenchymal stem cells-derived extracellular vesicles (MSC-EVs) have noticeably attracted clinicians' attention in treating ocular diseases. As the paracrine factor of MSCs and an alternative for cell-free therapies, MSC-EVs can be conveniently dropped over the ocular surface or diffused through the retina upon intravitreal injection, without increasing the risks of cellular rejection and tumor formation. For clinical translation, a standardized and scalable production, as well as reprogramming the MSC-EVs, are highly encouraged. This review aims to assess the potential approaches for EV production and functional modification, in addition to summarizing the worldwide clinical trials initiated for various physiological systems and the specific biochemical effects of MSC-EVs on the therapy of eye diseases. Recent advances in the therapy of ocular diseases based on MSC-EVs are reviewed, and the associated challenges and prospects are discussed as well.

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

Mesenchymal stem cells (MSCs), as the most common cell source for stem cell therapy, play an important role in the modulation of innate and adaptive immune responses and have been widely used in clinical trials to treat autoimmune and inflammatory diseases. Recent experimental and clinical studies have shown that MSC-derived extracellular vesicles (MSC-EVs) can inhibit the activation and proliferation of a variety of proinflammatory cells, such as Th1, Th17 and M1 macrophages, reducing the secretion of proinflammatory cytokines, while promoting the proliferation of anti-inflammatory cells, such as M2 macrophages and Tregs, and increasing the secretion of anti-inflammatory cytokines, thus playing a role in immune regulation and exhibiting immunomodulatory functions. Besides MSC-EVs are more convenient and less immunogenic than MSCs. There is growing interest in the role of MSC-EVs in liver diseases owing to the intrinsic liver tropism of MSC-EVs. In this review, we focus on the immunomodulatory effects of MSC-EVs and summarize the pivotal roles of MSC-EVs as a cell-free therapy in liver diseases, including NAFLD, AIH, acute liver failure, liver fibrosis and hepatic ischemia–reperfusion injury. Moreover, we provide a concise overview of the potential use and limits of MSC-EVs in clinical application.

The role and function of CD4+ T cells in hepatic ischemia-reperfusion injury

INTRODUCTION

Hepatic ischemia-reperfusion injury (IRI) is a severe complication frequently encountered in liver surgery, seriously affecting the therapeutic effects, tissue function. Various immune cells are involved in hepatic IRI, including macrophages, NKT cells, DCs, CD4 + T cells, and CD8 + T cells, among which CD4 + T cells play a critical role in this process. This article aims to summarize the functions and changes in various CD4 + T cell type counts and related cytokine levels in hepatic IRI and to review the possible mechanisms of mutual conversion between T cell types.

AREAS COVERED

We have covered the functions and changes that occur in Th1, Th17, and Treg cells in liver IRI, as well as the pathways and factors associated with them. We also discuss the prospects of clinical application and future directions for therapeutic advances.

EXPERT OPINION

This section explores the current clinical trials involving CD4 + T cells, especially Tregs, explains the limitations of their application, and summarizes the future development trends of cell engineering and their combination with the CAT technology. We also provide new ideas and therapeutic targets for alleviating liver IRI or other liver inflammatory diseases.

Effect of Edaravone on MicroRNA Expression in Exosomes after Hepatic Ischemia-reperfusion Injury

BACKGROUND AND OBJECTIVE

Hepatic ischemia-reperfusion injury (HIRI) results in serious complications after liver resection and transplantation. Edaravone (ED) has a protective effect on IRI. This study was designed to evaluate whether ED could protect the liver of rats from HIRI injury and explored its exosomal miRNA-related mechanism.

METHODS

The sham group, hepatic ischemia/reperfusion (IR group), and hepatic ischemia/reperfusion + edaravone (ED group) models were established. We determined the protective effect of ED by measuring alanine aminotransferase (ALT), aspartate aminotransferase (AST), malondialdehyde (MDA), superoxide dismutase (SOD); enzyme-linked immunosorbent assay for tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β); hematoxylin-eosin staining and immunohistochemistry for histopathological changes. Exosomal miRNAs were subjected to second-generation sequencing to identify their differential expression. The results were analyzed using bioinformatics methods and validated using real-time quantitative polymerase chain reaction (RT-qPCR).

RESULTS

HIRI rats showed higher levels of ALT, AST, oxidative stress, and inflammatory markers; ED attenuated these effects. The sequencing results showed 6 upregulated and 13 downregulated miRNAs in the IR vs. sham groups, 10 upregulated and 10 downregulated miRNAs in the ED vs. IR groups. PC-3p-190-42101 was screened as an overlapping differentially expressed miRNA, and RT-qPCR validation showed that its expression in HIRI rats was significantly decreased; ED prevented this downregulation. Moreover, the expression of PC-3P-190-42101 was significantly correlated with the level of inflammatory factors.

CONCLUSION

These findings indicate that ED can regulate the level of inflammatory factors by affecting the expression of miRNA PC-3p-190-42101 in plasma exosomes to protect the liver from IRI.

Mesenchymal Stem Cells Influence Activation of Hepatic Stellate Cells, and Constitute a Promising Therapy for Liver Fibrosis

Liver fibrosis is a common feature of chronic liver disease. Activated hepatic stellate cells (HSCs) are the main drivers of extracellular matrix accumulation in liver fibrosis. Hence, a strategy for regulating HSC activation is crucial in treating liver fibrosis. Mesenchymal stem cells (MSCs) are multipotent stem cells derived from various post-natal organs. Therapeutic approaches involving MSCs have been studied extensively in various diseases, including liver disease. MSCs modulate hepatic inflammation and fibrosis and/or differentiate into hepatocytes by interacting directly with immune cells, HSCs, and hepatocytes and secreting modulators, thereby contributing to reduced liver fibrosis. Cell-free therapy including MSC-released secretomes and extracellular vesicles has elicited extensive attention because they could overcome MSC transplantation limitations. Herein, we provide basic information on hepatic fibrogenesis and the therapeutic potential of MSCs. We also review findings presenting the effects of MSC itself and MSC-based cell-free treatments in liver fibrosis, focusing on HSC activation. Growing evidence supports the anti-fibrotic function of either MSC itself or MSC modulators, although the mechanism underpinning their effects on liver fibrosis has not been established. Further studies are required to investigate the detailed mechanism explaining their functions to expand MSC therapies using the cell itself and cell-free treatments for liver fibrosis.

Mesenchymal Stem Cells: Potential Therapeutic Prospect of Paracrine Pathways in Neonatal Infection

Infection is the leading cause of admission and mortality in neonatal intensive care units. Immature immune function and antibiotic resistance make the treatment more difficult. However, there is no effective prevention for it. Recently, more and more researches are focusing on stem cell therapy, especially mesenchymal stem cells (MSCs); their potential paracrine effect confer MSCs with a major advantage to treat the immune and inflammatory disorders associated with neonatal infection. In this review, we summarize the basal properties and preclinical evidence of MSCs and explore the potential mechanisms of paracrine factors of MSCs for neonatal infection.

Therapeutic Potential of Mesenchymal Stromal Cell-Derived Extracellular Vesicles in the Prevention of Organ Injuries Induced by Traumatic Hemorrhagic Shock

Severe trauma is the principal cause of death among young people worldwide. Hemorrhagic shock is the leading cause of death after severe trauma. Traumatic hemorrhagic shock (THS) is a complex phenomenon associating an absolute hypovolemia secondary to a sudden and significant extravascular blood loss, tissue injury, and, eventually, hypoxemia. These phenomena are responsible of secondary injuries such as coagulopathy, endotheliopathy, microcirculation failure, inflammation, and immune activation. Collectively, these dysfunctions lead to secondary organ failures and multi-organ failure (MOF). The development of MOF after severe trauma is one of the leading causes of morbidity and mortality, where immunological dysfunction plays a central role. Damage-associated molecular patterns induce an early and exaggerated activation of innate immunity and a suppression of adaptive immunity. Severe complications are associated with a prolonged and dysregulated immune–inflammatory state. The current challenge in the management of THS patients is preventing organ injury, which currently has no etiological treatment available. Modulating the immune response is a potential therapeutic strategy for preventing the complications of THS. Mesenchymal stromal cells (MSCs) are multipotent cells found in a large number of adult tissues and used in clinical practice as therapeutic agents for immunomodulation and tissue repair. There is growing evidence that their efficiency is mainly attributed to the secretion of a wide range of bioactive molecules and extracellular vesicles (EVs). Indeed, different experimental studies revealed that MSC-derived EVs (MSC-EVs) could modulate local and systemic deleterious immune response. Therefore, these new cell-free therapeutic products, easily stored and available immediately, represent a tremendous opportunity in the emergency context of shock. In this review, the pathophysiological environment of THS and, in particular, the crosstalk between the immune system and organ function are described. The potential therapeutic benefits of MSCs or their EVs in treating THS are discussed based on the current knowledge. Understanding the key mechanisms of immune deregulation leading to organ damage is a crucial element in order to optimize the preparation of EVs and potentiate their therapeutic effect.

Extracellular vesicles for tissue repair and regeneration: Evidence, challenges and opportunities

Extracellular vesicles (EVs) are biological nanoparticles naturally secreted by cells, acting as delivery vehicles for molecular messages. During the last decade, EVs have been assigned multiple functions that have established their potential as therapeutic mediators for a variety of diseases and conditions. In this review paper, we report on the potential of EVs in tissue repair and regeneration. The regenerative properties that have been associated with EVs are explored, detailing the molecular cargo they carry that is capable of mediating such effects, the signaling cascades triggered in target cells and the functional outcome achieved. EV interactions and biodistribution in vivo that influence their regenerative effects are also described, particularly upon administration in combination with biomaterials. Finally, we review the progress that has been made for the successful implementation of EV regenerative therapies in a clinical setting.

Human umbilical cord mesenchymal stem cells-derived exosomal microRNA-181a retards nasopharyngeal carcinoma development by mediating KDM5C

OBJECTIVE

It has been studied that mesenchymal stem cells (MSCs)-derived exosomes could suppress tumor growth in nasopharyngeal carcinoma (NPC) and microRNA-181a (miR-181a) could mediate drug resistance in NPC. Focused on this work, the mechanism of human umbilical cord MSCs (hUC-MSCs)-derived exosomal miR-181a was explored in NPC cell progression.

METHODS

NPC tissues and normal tissues were obtained from patients, and miR-181a and KDM5C expression was examined. hUC-MSCs-derived exosomes were extracted, identified and co-cultured with NPC cells (C666-1 and SUNE1). C666-1 cell progression in vitro and/or tumor growth in vivo were examined after incubation with exosomes, miR-181a or lysine-specific demethylase 5C (KDM5C). miR-181a and KDM5C expression were examined in NPC.

RESULTS

miR-181a expression was reduced while KDM5C expression was elevated in NPC. hUC-MSCs-derived exosomes restrained NPC cell growth in vivo and in vitro. Depleting or restoring exosomal miR-181a promoted or delayed NPC cell progression. KDM5C silencing suppressed NPC cell progression.

CONCLUSION

This study concluded that hUC-MSCs-derived exosomal miR-181a retards NPC development via negatively modulating KDM5C, serving as a candidate reference for the therapy of NPC.

MicroRNA profiling in Chinese children with Henoch-Schonlein purpura and association between selected microRNAs and inflammatory biomarkers

AIM

This study aimed to profile the microRNA levels in Chinese Henoch-Schonlein purpura (HSP) children and to explore their association with inflammatory factors and T helper 17 (Th17)/regulatory T (Treg).

METHODS

Forty-five HSP children and 27 healthy controls were enrolled in this study, and microRNA levels were profiled with a microRNA microarray. The levels of selected microRNAs were determined by quantitative real-time PCR, and the levels of serum IgA, interleukin-6, interleukin-10 and interleukin-17A were detected by enzyme-linked immunosorbent assay. Additionally, Th17 and Treg cells were analysed by flow cytometry.

RESULTS

There were 9 up-regulated and 27 down-regulated microRNAs in the PBMCs of Chinese HSP children. Among them, miR-1-3p, miR-19b-1-5p and miR-29b-1-5p were up-regulated, while miR-483-5p and miR-1246 were down-regulated. Additionally, these selected microRNAs could differentiate HSP patients from healthy controls. Interestingly, miR-29b-1-5p was correlated with IgA, miR-19b-1-5p, miR-483-5p and miR-1246 were correlated with interleukin-6, while miR-1-3p and miR-1246 were correlated with Th17/Treg.

CONCLUSION

This study reveals that the altered microRNAs could differentiate HSP from the healthy, and were associated with inflammatory factors or Th17/Treg. It is indicated that alteration in these microRNAs may contribute to the HSP pathogenesis and may become therapeutic targets or diagnostic biomarkers for HSP.

Exosomal microRNAs as diagnostic and therapeutic biomarkers in non-malignant liver diseases

The liver is a vital organ responsible for various physiological functions, such as metabolism, immune response, digestion, and detoxification. Crosstalk between hepatocytes, hepatic macrophages, and hepatic stellate cells is critical for liver pathology. Exosomes are small extracellular vesicles (50-150 nm) that play an important role in cell-cell or organ-organ communication as they transfer their cargo, such as protein, DNA, and RNA to recipient cells or distant organs. In various liver diseases, the number of liver cell-derived exosomes is increased and the exosomal microRNA (miRNA) profile is altered. Early studies investigated the value of circulating exosomal miRNAs as biomarkers. Several exosomal miRNAs showed excellent diagnostic values, suggesting their potential as diagnostic biomarkers in liver diseases. Exosomal miRNAs have emerged as critical regulators of liver pathology because they control the expression of multiple genes in recipient cells. In this review, we discuss the biology of exosomes and summarize the recent findings of exosome-mediated intercellular and organ-to-organ communication during liver pathology. As there are many review articles dealing with exosomal miRNAs in liver cancer, we focused on non-malignant liver diseases. The therapeutic potential of exosomal miRNAs in liver pathology is also highlighted.

Bone marrow mesenchymal stem cell-derived exosomes induce the Th17/Treg imbalance in immune thrombocytopenia through miR-146a-5p/IRAK1 axis

Bone marrow mesenchymal stem cells (BMSCs) are associated with immune thrombocytopenia (ITP), the underlying mechanism has not been fully elucidated. Here, we attempted to investigate whether BMSCs can regulate Th17/Treg imbalance in ITP through the exosome pathway. We first assessed the proportions of Th17 cells and Tregs in ITP patients, showing that ITP patients exhibited an evident imbalance of Th17/Treg. BMSCs-exosomes' treatment significantly reduced Th17/Treg ratio in the CD4⁺ T cells of ITP patients. Moreover, miR-146a-5p was highly expressed in BMSCs-exosomes. The expression of miR-146a-5p was obviously increased in CD4⁺ T cells following the treatment of BMSCs-exosomes. BMSCs-exosomal miR-146a-5p silencing promoted the proportions of Th17 cells and repressed the proportions of Tregs in CD4⁺ T cells. In addition, miR-146a-5p directly interacted with IL-1R-associated kinase-1 (IRAK), and repressed IRAK1 expression. IRAK1 overexpression promoted Th17/Treg ratio in CD4⁺ T cells, which was abolished by BMSCs-exosomal miR-146a-5p. In conclusion, these findings demonstrate that BMSC-derived exosomal miR-146a-5p regulates Th17/Treg imbalance in ITP by repressing IRAK1 expression. Thus, this work suggests that BMSCs-exosomal miR-146a-5p may be a potential therapeutic target for ITP.

miRNAs Alter T Helper 17 Cell Fate in the Pathogenesis of Autoimmune Diseases

T helper 17 (Th17) cells are characterized by the secretion of the IL-17 cytokine and are essential for the immune response against bacterial and fungal infections. Despite the beneficial roles of Th17 cells, unrestrained IL-17 production can contribute to immunopathology and inflammatory autoimmune diseases, including multiple sclerosis, rheumatoid arthritis, and inflammatory bowel disease. Although these diverse outcomes are directed by the activation of Th17 cells, the regulation of Th17 cells is incompletely understood. The discovery that microRNAs (miRNAs) are involved in the regulation of Th17 cell differentiation and function has greatly improved our understanding of Th17 cells in immune response and disease. Here, we provide an overview of the biogenesis and function of miRNA and summarize the role of miRNAs in Th17 cell differentiation and function. Finally, we focus on recent advances in miRNA-mediated dysregulation of Th17 cell fate in autoimmune diseases.

Exosomes derived from mesenchymal stem cells regulate Treg/Th17 balance in aplastic anemia by transferring miR-23a-3p

Imbalanced Th17/Treg ratio is implicated in the pathogenesis of aplastic anemia. Studies have indicated that bone marrow-derived mesenchymal stem cells-derived exosomes (BMSC-Exo) could correct imbalanced Th17/Treg in aplastic anemia, but the mechanism remains not fully understand. This study was designed to investigate whether BMSC-Exo regulates the Th17/Treg balance in aplastic anemia by transferring miR-23a-3p. Here, miR-23a-3p inhibitor was utilized to knockdown the expression of miR-23a-3p in BMSC-Exo. A co-culture system of CD4⁺ T cells from aplastic anemia patients and BMSC-Exo was used to explore the effects of BMSC-Exo on the Th17/Treg balance and the underlying mechanism in aplastic anemia. The patients with aplastic anemia exhibited Th17/Treg imbalance favoring the Th17 cells. BMSC-Exo could balance the percentage of Th17 and Treg cells in aplastic anemia, but the effects of BMSC-Exo can be eliminated when miR-23a-3p expression was silenced in BMSCs. IL-6 was a direct target of miR-23a-3p. IL-6 overexpression could abrogate BMSC-Exo-induced balance in Th17/Treg ratio. Overall, BMSC-Exo could balance Th17/Treg ratio in aplastic anemia via suppressing IL-6 expression by transferring miR-23a-3p at least in part. These data indicated miR-23a-3p may be a potential target for the treatment of aplastic anemia. Our study may provide a new idea for the therapy of the disease.

Exosome-inflammasome crosstalk and their roles in inflammatory responses

Inflammasome is a complex of multiple proteins found in cytoplasm of the cells activated by infectious and/or non-infectious stimuli. This complex involves caspase-1 activation, leading to unconventional secretion of interleukin-1β (IL-1β) and IL-18 and inflammatory cascade. Exosome is the nanoscale membrane-bound extracellular vesicle that plays significant roles in intercellular communications by carrying bioactive molecules, e.g., proteins, RNAs, microRNAs (miRNAs), DNAs, from one cell to the others. In this review, we provide the update information on the crosstalk between exosome and inflammasome and their roles in inflammatory responses. The effects of inflammasome activation on exosomal secretion are summarized. On the other hand, the (dual) effects of exosomes on inhibiting and promoting inflammasome activation are discussed. Finally, perspectives on therapeutic roles of exosomes in human diseases and future direction of the research on exosome-inflammasome crosstalk are provided.

Exosomes derived from thymic stromal lymphopoietin-treated dendritic cells regulate T helper 17/regulatory T cell differentiation via miR-21/Smad7 axis

Thymic stromal lymphopoietin (TSLP) is associated with fungal keratitis. This work aims to investigate whether TSLP can regulate T helper (Th) 17 and regulatory T cell (Treg) differentiation. We separated dendritic cells (DCs) from peripheral blood of healthy volunteers. DCs were treated with TSLP to activate DCs, and exosomes were obtained. CD⁺ T cells were incubated with exosomes from TSLP-treated DCs. We found that exosomes from TSLP-treated DCs notably promoted the proportions of Th17 cells and inhibited the proportions of Tregs in the CD4⁺ T cells. Moreover, exosomes from TSLP-treated DCs enhanced the expression of retinoid-related orphan receptor γt (RORγt) and interleukin 17 (IL-17), and repressed the expression of forkhead box protein P3 (Foxp3) and interleukin 10 (IL-10) in the CD4⁺ T cells. Furthermore, miR-21 was highly expressed in exosomes from TSLP-treated DCs. Exosomes from TSLP-treated miR-21-silenced DCs promoted Treg differentiation and suppressed Th17 differentiation. Smad7 up-regulation repressed Th17 differentiation and enhanced Treg differentiation, which was abolished by miR-21 overexpression. Smad7 overexpression rescued the effect of exosomes from TSLP-treated DCs on Th17/Treg differentiation. In conclusion, our article confirms that TSLP induces DCs to deliver miR-21 by secreting exosomes, and thus miR-21 regulates Th17/Treg differentiation by inhibiting Smad7. Thus, this work further reveals the biological role of miR-21 in fungal keratitis.

Immunosuppressive Effects of Mesenchymal Stem Cells-derived Exosomes

Mesenchymal stem cells (MSCs) have become important seed cells in therapy because of their immunosuppressive function and anti-inflammatory effects. MSCs exert immunosuppressive effects through direct contact or paracrine action. The paracrine functions of MSCs are at least partially mediated by exosomes, which are membrane vesicles, carrying abundant proteins, nucleic acids and other active molecules. MSC-exos have heterogeneity. The exosomes from different donors, tissues generations of MSCs carry different bioactive molecules. These cargos are transferred to recipient cells by endocytosis or binding to proteins on the receptor surface to mediate intercellular communication between different cell types and affect the functions of the recipient cells. Exosomes play an important role in the regulation of the immune system. Exosomes derived from MSCs (MSC-exos) carry immunomodulatory effectors or transmit active signal molecules to regulate the biological activities of immune cells and thus mediating immune suppression, especially on macrophages and T cells. Mitochondria and autophagy-related pathways are also associated with MSC-exos immunosuppressive effects. Graphical Abstract.

Acidic Microenvironment Regulates the Severity of Hepatic Ischemia/Reperfusion Injury by Modulating the Generation and Function of Tregs via the PI3K-mTOR Pathway

Hepatic ischemia/reperfusion injury (HIRI) is a major cause of liver dysfunction and even liver failure after liver transplantation and hepatectomy. One of the critical mechanisms that lead to HIRI is an acidic microenvironment, which develops due to the accumulation of high acid-like substances such as lactic acid and ketone bodies. Previous studies have shown that the adoptive transfer of induced regulatory T cells (iTregs) attenuates HIRI; however, little is known about the function of Tregs in the acidic microenvironment of a HIRI model. In the present study, we examined the effect of acidic microenvironment on Tregs in vitro and in vivo. Here, we report that microenvironment acidification and dysfunction of the liver is induced during HIRI in humans and mice and that an acidic microenvironment can inhibit the generation and function of CD4⁺CD25⁺Foxp3⁺ iTregs via the PI3K/Akt/mTOR signaling pathway. By contrast, the reversal of the acidic microenvironment restored Foxp3 expression and iTreg function. In addition, the results of cell culture in vitro indicated that the proton pump inhibitor omeprazole improves decreased iTreg differentiation caused by the acidic microenvironment, suggesting the potential clinical use of proton pump inhibitors as immunoregulatory therapy in the treatment of HIRI. Furthermore, our findings demonstrate that buffering the acidic microenvironment to attenuate HIRI in mice has an inseparable relationship with Tregs. Thus, an acidic microenvironment is a key regulator in HIRI, involved in modulating the generation and function of Tregs.