Immunomodulatory effects of extracellular vesicles from mesenchymal stromal cells: Implication for therapeutic approach in autoimmune diseases.

Autoimmune disease is characterized by the proliferation of harmful immune cells, inducing tissue inflammation and ultimately causing organ damage. Current treatments often lack specificity, necessitating high doses, prolonged usage, and high recurrence rates. Therefore, the identification of innovative and safe therapeutic strategies is urgently required. Recent preclinical studies and clinical trials on inflammatory and autoimmune diseases have evidenced the immunosuppressive properties of mesenchymal stromal cells (MSCs). Studies have demonstrated that extracellular vesicles (EV) derived from MSCs can mitigate abnormal autoinflammation while maintaining safety within the diseased microenvironment. This study conducted a systematic review to elucidate the crucial role of MSC-EVs in alleviating autoimmune diseases, particularly focusing on their impact on the underlying mechanisms of autoimmune conditions such as rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), and inflammatory bowel disease (IBD). By specifically examining the regulatory functions of microRNAs (miRNAs) derived from MSC-EVs, the comprehensive study aimed to enhance the understanding related to disease mechanisms and identify potential diagnostic markers and therapeutic targets for these diseases.

Preclinical and Clinical Studies on the Use of Extracellular Vesicles Derived from Mesenchymal Stem Cells in the Treatment of Chronic Wounds.

To date, the widespread implementation of therapeutic strategies for the treatment of chronic wounds, including debridement, infection control, and the use of grafts and various dressings, has been time-consuming and accompanied by many challenges, with definite success not yet achieved. Extensive studies on mesenchymal stem cells (MSCs) have led to suggestions for their use in treating various diseases. Given the existing barriers to utilizing such cells and numerous pieces of evidence indicating the crucial role of the paracrine signaling system in treatments involving MSCs, extracellular vesicles (EVs) derived from these cells have garnered significant attention in treating chronic wounds in recent years. This review begins with a general overview of current methods for chronic wound treatment, followed by an exploration of EV structure, biogenesis, extraction methods, and characterization. Subsequently, utilizing databases such as Google Scholar, PubMed, and ScienceDirect, we have explored the latest findings regarding the role of EVs in the healing of chronic wounds, particularly diabetic and burn wounds. In this context, the role and mode of action of these nanoparticles in healing chronic wounds through mechanisms such as oxygen level elevation, oxidative stress damage reduction, angiogenesis promotion, macrophage polarization assistance, etc., as well as the use of EVs as carriers for engineered nucleic acids, have been investigated. The upcoming challenges in translating EV-based treatments for healing chronic wounds, along with possible approaches to address these challenges, are discussed. Additionally, clinical trial studies in this field are also covered.

Endothelial cell-derived extracellular vesicles modulate the therapeutic efficacy of mesenchymal stem cells through IDH2/TET pathway in ARDS.

BACKGROUND: Acute respiratory distress syndrome (ARDS) is a severe and fatal disease. Although mesenchymal stem cell (MSC)-based therapy has shown remarkable efficacy in treating ARDS in animal experiments, clinical outcomes have been unsatisfactory, which may be attributed to the influence of the lung microenvironment during MSC administration. Extracellular vesicles (EVs) derived from endothelial cells (EC-EVs) are important components of the lung microenvironment and play a crucial role in ARDS. However, the effect of EC-EVs on MSC therapy is still unclear. In this study, we established lipopolysaccharide (LPS) - induced acute lung injury model to evaluate the impact of EC-EVs on the reparative effects of bone marrow-derived MSC (BM-MSC) transplantation on lung injury and to unravel the underlying mechanisms. METHODS: EVs were isolated from bronchoalveolar lavage fluid of mice with LPS - induced acute lung injury and patients with ARDS using ultracentrifugation. and the changes of EC-EVs were analysed using nanoflow cytometry analysis. In vitro assays were performed to establish the impact of EC-EVs on MSC functions, including cell viability and migration, while in vivo studies were performed to validate the therapeutic effect of EC-EVs on MSCs. RNA-Seq analysis, small interfering RNA (siRNA), and a recombinant lentivirus were used to investigate the underlying mechanisms. RESULTS: Compared with that in non-ARDS patients, the quantity of EC-EVs in the lung microenvironment was significantly greater in patients with ARDS. EVs derived from lipopolysaccharide-stimulated endothelial cells (LPS-EVs) significantly decreased the viability and migration of BM-MSCs. Furthermore, engrafting BM-MSCs pretreated with LPS-EVs promoted the release of inflammatory cytokines and increased pulmonary microvascular permeability, aggravating lung injury. Mechanistically, LPS-EVs reduced the expression level of isocitrate dehydrogenase 2 (IDH2), which catalyses the formation of α-ketoglutarate (α-KG), an intermediate product of the tricarboxylic acid (TCA) cycle, in BM-MSCs. α-KG is a cofactor for ten-eleven translocation (TET) enzymes, which catalyse DNA hydroxymethylation in BM-MSCs. CONCLUSIONS: This study revealed that EC-EVs in the lung microenvironment during ARDS can affect the therapeutic efficacy of BM-MSCs through the IDH2/TET pathway, providing potential strategies for improving the therapeutic efficacy of MSC-based therapy in the clinic.

circCDK13-loaded small extracellular vesicles accelerate healing in preclinical diabetic wound models.

Chronic wounds are a major complication in patients with diabetes. Here, we identify a therapeutic circRNA and load it into small extracellular vesicles (sEVs) to treat diabetic wounds in preclinical models. We show that circCDK13 can stimulate the proliferation and migration of human dermal fibroblasts and human epidermal keratinocytes by interacting with insulin-like growth factor 2 mRNA binding protein 3 in an N6-Methyladenosine-dependent manner to enhance CD44 and c-MYC expression. We engineered sEVs that overexpress circCDK13 and show that local subcutaneous injection into male db/db diabetic mouse wounds and wounds of streptozotocin-induced type I male diabetic rats could accelerate wound healing and skin appendage regeneration. Our study demonstrates that the delivery of circCDK13 in sEVs may present an option for diabetic wound treatment.

Extracellular vesicles as human therapeutics: A scoping review of the literature.

Extracellular vesicles (EVs) are released by all cells and contribute to cell-to-cell communication. The capacity of EVs to target specific cells and to efficiently deliver a composite profile of functional molecules have led researchers around the world to hypothesize their potential as therapeutics. While studies of EV treatment in animal models are numerous, their actual clinical benefit in humans has more slowly started to be tested. In this scoping review, we searched PubMed and other databases up to 31 December 2023 and, starting from 13,567 records, we selected 40 pertinent published studies testing EVs as therapeutics in humans. The analysis of those 40 studies shows that they are all small pilot trials with a large heterogeneity in terms of administration route and target disease. Moreover, the absence of a placebo control in most of the studies, the predominant local application of EV formulations and the inconsistent administration dose metric still impede comparison across studies and firm conclusions about EV safety and efficacy. On the other hand, the recording of some promising outcomes strongly calls out for well-designed larger studies to test EVs as an alternative approach to treat human diseases with no or few therapeutic options.

Head-to-head comparison of relevant cell sources of small extracellular vesicles for cardiac repair: Superiority of embryonic stem cells.

Small extracellular vesicles (sEV) derived from various cell sources have been demonstrated to enhance cardiac function in preclinical models of myocardial infarction (MI). The aim of this study was to compare different sources of sEV for cardiac repair and determine the most effective one, which nowadays remains limited. We comprehensively assessed the efficacy of sEV obtained from human primary bone marrow mesenchymal stromal cells (BM-MSC), human immortalized MSC (hTERT-MSC), human embryonic stem cells (ESC), ESC-derived cardiac progenitor cells (CPC), human ESC-derived cardiomyocytes (CM), and human primary ventricular cardiac fibroblasts (VCF), in in vitro models of cardiac repair. ESC-derived sEV (ESC-sEV) exhibited the best pro-angiogenic and anti-fibrotic effects in vitro. Then, we evaluated the functionality of the sEV with the most promising performances in vitro, in a murine model of MI-reperfusion injury (IRI) and analysed their RNA and protein compositions. In vivo, ESC-sEV provided the most favourable outcome after MI by reducing adverse cardiac remodelling through down-regulating fibrosis and increasing angiogenesis. Furthermore, transcriptomic, and proteomic characterizations of sEV derived from hTERT-MSC, ESC, and CPC revealed factors in ESC-sEV that potentially drove the observed functions. In conclusion, ESC-sEV holds great promise as a cell-free treatment for promoting cardiac repair following MI.

Mitigation of acute lung injury by human bronchial epithelial cell-derived extracellular vesicles via ANXA1-mediated FPR signaling.

Acute lung injury (ALI) is characterized by respiratory failure resulting from the disruption of the epithelial and endothelial barriers as well as immune system. In this study, we evaluated the therapeutic potential of airway epithelial cell-derived extracellular vesicles (EVs) in maintaining lung homeostasis. We isolated human bronchial epithelial cell-derived EVs (HBEC-EVs), which endogenously express various immune-related surface markers and investigated their immunomodulatory potential in ALI. In ALI cellular models, HBEC-EVs demonstrated immunosuppressive effects by reducing the secretion of proinflammatory cytokines in both THP-1 macrophages and HBECs. Mechanistically, these effects were partially ascribed to nine of the top 10 miRNAs enriched in HBEC-EVs, governing toll-like receptor-NF-κB signaling pathways. Proteomic analysis revealed the presence of proteins in HBEC-EVs involved in WNT and NF-κB signaling pathways, pivotal in inflammation regulation. ANXA1, a constituent of HBEC-EVs, interacts with formyl peptide receptor (FPR)2, eliciting anti-inflammatory responses by suppressing NF-κB signaling in inflamed epithelium, including type II alveolar epithelial cells. In a mouse model of ALI, intratracheal administration of HBEC-EVs reduced lung injury, inflammatory cell infiltration, and cytokine levels. Collectively, these findings suggest the therapeutic potential of HBEC-EVs, through their miRNAs and ANXA1 cargo, in mitigating lung injury and inflammation in ALI patients.

Cystatin C loaded in brain-derived extracellular vesicles rescues synapses after ischemic insult in vitro and in vivo.

Synaptic loss is an early event in the penumbra area after an ischemic stroke. Promoting synaptic preservation in this area would likely improve functional neurological recovery. We aimed to detect proteins involved in endogenous protection mechanisms of synapses in the penumbra after stroke and to analyse potential beneficial effects of these candidates for a prospective stroke treatment. For this, we performed Liquid Chromatography coupled to Mass Spectrometry (LC-MS)-based proteomics of synaptosomes isolated from the ipsilateral hemispheres of mice subjected to experimental stroke at different time points (24 h, 4 and 7 days) and compared them to sham-operated mice. Proteomic analyses indicated that, among the differentially expressed proteins between the two groups, cystatin C (CysC) was significantly increased at 24 h and 4 days following stroke, before returning to steady-state levels at 7 days, thus indicating a potential transient and intrinsic rescue mechanism attempt of neurons. When CysC was applied to primary neuronal cultures subjected to an in vitro model of ischemic damage, this treatment significantly improved the preservation of synaptic structures. Notably, similar effects were observed when CysC was loaded into brain-derived extracellular vesicles (BDEVs). Finally, when CysC contained in BDEVs was administered intracerebroventricularly to stroked mice, it significantly increased the expression of synaptic markers such as SNAP25, Homer-1, and NCAM in the penumbra area compared to the group supplied with empty BDEVs. Thus, we show that CysC-loaded BDEVs promote synaptic protection after ischemic damage in vitro and in vivo, opening the possibility of a therapeutic use in stroke patients.

Systems Approaches to Cell Culture-Derived Extracellular Vesicles for Acute Kidney Injury Therapy: Prospects and Challenges.

Acute kidney injury (AKI) is a heterogeneous syndrome, comprising diverse etiologies of kidney insults that result in high mortality and morbidity if not well managed. Although great efforts have been made to investigate underlying pathogenic mechanisms of AKI, there are limited therapeutic strategies available. Extracellular vesicles (EV) are membrane-bound vesicles secreted by various cell types, which can serve as cell-free therapy through transfer of bioactive molecules. In this review, we first overview the AKI syndrome and EV biology, with a particular focus on the technical aspects and therapeutic application of cell culture-derived EVs. Second, we illustrate how multi-omic approaches to EV miRNA, protein, and genomic cargo analysis can yield new insights into their mechanisms of action and address unresolved questions in the field. We then summarize major experimental evidence regarding the therapeutic potential of EVs in AKI, which we subdivide into stem cell and non-stem cell-derived EVs. Finally, we highlight the challenges and opportunities related to the clinical translation of animal studies into human patients.

Emerging Strategies in Mesenchymal Stem Cell-Based Cardiovascular Therapeutics.

Cardiovascular diseases continue to challenge global health, demanding innovative therapeutic solutions. This review delves into the transformative role of mesenchymal stem cells (MSCs) in advancing cardiovascular therapeutics. Beginning with a historical perspective, we trace the development of stem cell research related to cardiovascular diseases, highlighting foundational therapeutic approaches and the evolution of cell-based treatments. Recognizing the inherent challenges of MSC-based cardiovascular therapeutics, which range from understanding the pro-reparative activity of MSCs to tailoring patient-specific treatments, we emphasize the need to refine the pro-regenerative capacity of these cells. Crucially, our focus then shifts to the strategies of the fourth generation of cell-based therapies: leveraging the secretomic prowess of MSCs, particularly the role of extracellular vesicles; integrating biocompatible scaffolds and artificial sheets to amplify MSCs' potential; adopting three-dimensional ex vivo propagation tailored to specific tissue niches; harnessing the promise of genetic modifications for targeted tissue repair; and institutionalizing good manufacturing practice protocols to ensure therapeutic safety and efficacy. We conclude with reflections on these advancements, envisaging a future landscape redefined by MSCs in cardiovascular regeneration. This review offers both a consolidation of our current understanding and a view toward imminent therapeutic horizons.

Macrophage-derived extracellular vesicles alter cardiac recovery and metabolism in a rat heart model of donation after circulatory death.

Conditions to which the cardiac graft is exposed during transplantation with donation after circulatory death (DCD) can trigger the recruitment of macrophages that are either unpolarized (M0) or pro-inflammatory (M1) as well as the release of extracellular vesicles (EV). We aimed to characterize the effects of M0 and M1 macrophage-derived EV administration on post-ischaemic functional recovery and glucose metabolism using an isolated rat heart model of DCD. Isolated rat hearts were subjected to 20 min aerobic perfusion, followed by 27 min global, warm ischaemia or continued aerobic perfusion and 60 min reperfusion with or without intravascular administration of EV. Four experimental groups were compared: (1) no ischaemia, no EV; (2) ischaemia, no EV; (3) ischaemia with M0-macrophage-dervied EV; (4) ischaemia with M1-macrophage-derived EV. Post-ischaemic ventricular and metabolic recovery were evaluated. During reperfusion, ventricular function was decreased in untreated ischaemic and M1-EV hearts, but not in M0-EV hearts, compared to non-ischaemic hearts (p < 0.05). In parallel with the reduced functional recovery in M1-EV versus M0-EV ischaemic hearts, rates of glycolysis from exogenous glucose and oxidative metabolism tended to be lower, while rates of glycogenolysis and lactate release tended to be higher. EV from M0- and M1-macrophages differentially affect post-ischaemic cardiac recovery, potentially by altering glucose metabolism in a rat model of DCD. Targeted EV therapy may be a useful approach for modulating cardiac energy metabolism and optimizing graft quality in the setting of DCD.

miRNA-148a-containing GMSC-derived EVs modulate Treg/Th17 balance via IKKB/NF-κB pathway and treat a rheumatoid arthritis model.

Mesenchymal stem cells (MSCs) have demonstrated potent immunomodulatory properties that have shown promise in the treatment of autoimmune diseases, including rheumatoid arthritis (RA). However, the inherent heterogeneity of MSCs triggered conflicting therapeutic outcomes, raising safety concerns and limiting their clinical application. This study aimed to investigate the potential of extracellular vesicles derived from human gingival mesenchymal stem cells (GMSC-EVs) as a therapeutic strategy for RA. Through in vivo experiments using an experimental RA model, our results demonstrate that GMSC-EVs selectively homed to inflamed joints and recovered Treg and Th17 cell balance, resulting in the reduction of arthritis progression. Our investigations also uncovered miR-148a-3p as a critical contributor to the Treg/Th17 balance modulation via IKKB/NF-κB signaling orchestrated by GMSC-EVs, which was subsequently validated in a model of human xenograft versus host disease (xGvHD). Furthermore, we successfully developed a humanized animal model by utilizing synovial fibroblasts obtained from patients with RA (RASFs). We found that GMSC-EVs impeded the invasiveness of RASFs and minimized cartilage destruction, indicating their potential therapeutic efficacy in the context of patients with RA. Overall, the unique characteristics - including reduced immunogenicity, simplified administration, and inherent ability to target inflamed tissues - position GMSC-EVs as a viable alternative for RA and other autoimmune diseases.

Lung fibroblast-derived extracellular vesicles and soluble factors alleviate elastase-induced lung injury.

One of the main pathological features of chronic obstructive pulmonary disease (COPD) is the loss of functional alveolar tissue as a consequence of impaired regenerative capacities (emphysema). Recent research suggests that the secretome from mesenchymal cells, particularly extracellular vesicles (EVs), may possess regenerative properties beneficial for lung repair. However, the regenerative potential of the soluble factors (SFs) within the secretome remains largely unexplored in COPD. To this extent, we purified EVs and SFs secreted by lung fibroblasts to generate EV-enriched and SF-enriched fractions, and evaluated their effects on elastase-induced lung injury in both precision-cut lung slices (PCLS) and a mouse model. EV- and SF-enriched fractions were concentrated and purified from the conditioned medium of cultured MRC-5 lung fibroblasts using a combination of ultrafiltration and size exclusion chromatography, and were subsequently characterized according to the MISEV guidelines. Treatment with EV- or SF-enriched concentrates prevented and improved elastase-induced emphysema in PCLS, leading to reduced lung injury and upregulated markers of alveolar epithelial cells (aquaporin 5 and surfactant protein C), indicating potential parenchymal regeneration. Accordingly, prophylactic intratracheal treatment with lung fibroblast-derived EV- and SF-enriched concentrates in vivo attenuated elastase-induced lung tissue destruction, improved lung function, and enhanced gene expression of alveolar epithelial cell markers. Here, alveolar repair not only serves the purpose of facilitating gas exchange, but also by reinstating the essential parenchymal tethering required for optimal airway mechanics. In conclusion, this study highlights the therapeutic potential of both lung fibroblast-derived EV- and SF-enriched concentrates for the treatment of lung injury and emphysema.

M2 Macrophage-Derived Extracellular Vesicles Encapsulated in Hyaluronic Acid Alleviate Osteoarthritis by Modulating Macrophage Polarization.

An imbalance between M1 and M2 macrophage polarization is critical in osteoarthritis (OA) development. We investigated the effect of M2 macrophage-derived extracellular vesicles (M2-EVs) to reprogramme macrophages from the M1 to M2 phenotype for OA treatment. M1 macrophages and mouse OA models were treated with M2-EVs. Proteomic analysis was performed to evaluate macrophage polarization in vitro. The OA models were as follows: destabilization of the medial meniscus (DMM) surgery-induced OA and collagenase-induced OA (CIOA). Hyaluronic acid (HA) was used to deliver M2-EVs. M2-EVs decreased macrophage accumulation, repolarized macrophages from the M1 to M2 phenotype, mitigated synovitis, reduced cartilage degradation, alleviated subchondral bone damage, and improved gait abnormalities in the CIOA and DMM models. Moreover, HA increased the retention time of M2-EVs and enhanced the efficiency of M2-EVs in OA treatment. Furthermore, proteomic analysis demonstrated that M2-EVs exhibited a macrophage reprogramming ability similar to IL-4, and the pathways might be the NOD-like receptor (NLR), TNF, NF-κB, and Toll-like receptor (TLR) signaling pathways. M2-EVs reprogrammed macrophages from the M1 to M2 phenotype, which resulted in beneficial effects on cartilage and attenuation of OA severity. In summary, our study indicated that M2-EV-guided reprogramming of macrophages is a promising treatment strategy for OA.

Stem Cell Extracellular Vesicles as Anti-SARS-CoV-2 Immunomodulatory Therapeutics: A Systematic Review of Clinical and Preclinical Studies.

BACKGROUND: COVID-19 rapidly escalated into a worldwide pandemic with elevated infectivity even from asymptomatic patients. Complications can lead to severe pneumonia and acute respiratory distress syndrome (ARDS), which are the main contributors to death. Because of their regenerative and immunomodulatory capacities, stem cells and their derived extracellular vesicles (EVs) are perceived as promising therapies against severe pulmonary conditions, including those associated with COVID-19. Herein, we evaluate the safety and efficacy of stem cell EVs in treating COVID-19 and complicating pneumonia, acute lung injury, and ARDS. We also cover relevant preclinical studies to recapitulate the current progress in stem cell EV-based therapy. METHODS: Using PubMed, Cochrane Central Register of Controlled Trials, Scopus, and Web of Science, we searched for all English-language published studies (2000-2023) that used stem cell EVs as a therapy for COVID-19, ARDS, or pneumonia. The risk of bias (ROB) was assessed for all studies. RESULTS: Forty-eight studies met our inclusion criteria. Various-sized EVs derived from different types of stem cells were reported as a potentially safe and effective therapy to attenuate the cytokine storm induced by COVID-19. EVs alleviated inflammation and regenerated the alveolar epithelium by decreasing apoptosis, proinflammatory cytokines, neutrophil infiltration, and M2 macrophage polarization. They also prevented fibrin production and promoted the production of anti-inflammatory cytokines and endothelial cell junction proteins. CONCLUSION: Similar to their parental cells, stem cell EVs mediate lung tissue regeneration by targeting multiple pathways and thus hold promise in promoting the recovery of COVID-19 patients and improving the survival rate of severely affected patients.

Injury minimization after myocardial infarction: focus on extracellular vesicles.

Despite improvements in clinical outcomes following acute myocardial infarction, mortality remains high, especially in patients with severely reduced left ventricular ejection fraction (LVEF <30%), emphasizing the need for effective cardioprotective strategies adjunctive to recanalization. Traditional cell therapy has shown equivocal success, shifting the focus to innovative cardioactive biologicals and cell mimetic therapies, particularly extracellular vesicles (EVs). EVs, as carriers of non-coding RNAs and other essential biomolecules, influence neighbouring and remote cell function in a paracrine manner. Compared to cell therapy, EVs possess several clinically advantageous traits, including stability, ease of storage (enabling off-the-shelf clinical readiness), and decreased immunogenicity. Allogeneic EVs from mesenchymal and/or cardiac stromal progenitor cells demonstrate safety and potential efficacy in preclinical settings. This review delves into the translational potential of EV-based therapeutic approaches, specifically highlighting findings from large-animal studies, and offers a synopsis of ongoing early-stage clinical trials in this domain.

Mesenchymal Stem Cell-Derived Extracellular Vesicles: New Soldiers in the War on Immune-Mediated Diseases.

Inflammatory diseases are a group of debilitating disorders with varying degrees of long-lasting functional impairment of targeted system. New therapeutic agents that will attenuate on-going inflammation and, at the same time, promote regeneration of injured organ are urgently needed for the treatment of autoimmune and inflammatory disorders. During the last decade numerous studies have demonstrated that crucial therapeutic benefits of mesenchymal stem cells (MSCs) in inflammatory diseases are based on the effects of MSC-produced paracrine mediators and not on the activity of engrafted cells themselves. Thus, to overcome the limitations of stem cell transplantation, MSC-derived extracellular vesicles (MSC-EVs) have been rigorously investigated, as a promising cell-free pharmaceutical component. In this review, we focus on the mechanisms of MSC-EV covering the current knowledge on their potential therapeutic applications for immune-mediated diseases.

Therapeutic potentials of mesenchymal stromal cells-derived extracellular vesicles in liver failure and marginal liver graft rehabilitation: a scoping review.

Liver failure includes distinct subgroups of diseases: Acute liver failure (ALF) without preexisting cirrhosis, acute-on-chronic liver failure (ACLF) (severe form of cirrhosis associated with organ failures and excess mortality), and liver fibrosis (LF). Inflammation plays a key role in ALF, LF, and more specifically in ACLF for which we have currently no treatment other than liver transplantation (LT). The increasing incidence of marginal liver grafts and the shortage of liver grafts require us to consider strategies to increase the quantity and quality of available liver grafts. Mesenchymal stromal cells (MSCs) have shown beneficial pleiotropic properties with limited translational potential due to the pitfalls associated with their cellular nature. MSC-derived extracellular vesicles (MSC-EVs) are innovative cell-free therapeutics for immunomodulation and regenerative purposes. MSC-EVs encompass further advantages: pleiotropic effects, low immunogenicity, storage stability, good safety profile, and possibility of bioengineering. Currently, no human studies explored the impact of MSC-EVs on liver disease, but several preclinical studies highlighted their beneficial effects. In ALF and ACLF, data showed that MSC-EVs attenuate hepatic stellate cells activation, exert antioxidant, anti-inflammatory, anti-apoptosis, anti-ferroptosis properties, and promote regeneration of the liver, autophagy, and improve metabolism through mitochondrial function recovery. In LF, MSC-EVs demonstrated anti-fibrotic properties associated with liver tissue regeneration. Normothermic-machine perfusion (NMP) combined with MSC-EVs represents an attractive therapy to improve liver regeneration before LT. Our review suggests a growing interest in MSC-EVs in liver failure and gives an appealing insight into their development to rehabilitate marginal liver grafts through NMP.

Regenerative and Anti-Inflammatory Potential of Regularly Fed, Starved Cells and Extracellular Vesicles In Vivo.

BACKGROUND: Mesenchymal stem/stromal cells (MSC) have been employed successfully in immunotherapy and regenerative medicine, but their therapeutic potential is reduced considerably by the ischemic environment that exists after transplantation. The assumption that preconditioning MSC to promote quiescence may result in increased survival and regenerative potential upon transplantation is gaining popularity. METHODS: The purpose of this work was to evaluate the anti-inflammatory and regenerative effects of human bone marrow MSC (hBM-MSC) and their extracellular vesicles (EVs) grown and isolated in a serum-free medium, as compared to starved hBM-MSC (preconditioned) in streptozotocin-induced diabetic fractured male C57BL/6J mice. RESULTS: Blood samples taken four hours and five days after injection revealed that cells, whether starved or not, generated similar plasma levels of inflammatory-related cytokines but lower levels than animals treated with EVs. Nonetheless, starved cells prompted the highest production of IL-17, IL-6, IL-13, eotaxin and keratinocyte-derived chemokines and induced an earlier soft callus formation and mineralization of the fracture site compared to EVs and regularly fed cells five days after administration. CONCLUSIONS: Preconditioning may be crucial for refining and defining new criteria for future MSC therapies. Additionally, the elucidation of mechanisms underpinning an MSC's survival/adaptive processes may result in increased cell survival and enhanced therapeutic efficacy following transplantation.

Therapeutic efficacy of extracellular vesicles to suppress allograft rejection in preclinical kidney transplantation models: A systematic review and meta-analysis.

BACKGROUND: Kidney transplantation is the optimal treatment of end-stage renal disease. Extracellular vesicles (EVs) have tremendous therapeutic potential, but their role in modulating immune responses in kidney transplantation remains unclear. METHODS: We performed a systematic review and meta-analysis to investigate the therapeutic efficacy of EVs in preclinical kidney transplant models. Outcomes for meta-analysis were graft survival and renal function. Subgroup analysis was conducted between immune cell derived EVs (immune cell-EVs) and mesenchymal stromal cell derived EVs (MSC-EVs). RESULTS: Seven studies published from 2013 to 2021 were included. The overall effects showed that EVs had a positive role in prolonging allograft survival (standardized mean difference (SMD) = 2.00; 95% confidence interval (CI), 0.79 to 3.21; P < 0.01; I2 = 94%), reducing serum creatinine (SCr) (SMD = -2.19; 95%CI, -3.35 to -1.04; P < 0.01; I2 = 93%) and blood urea nitrogen (BUN) concentrations (SMD = -1.69; 95%CI, -2.98 to -0.40; P = 0.01; I2 = 94%). Subgroup analyses indicated that only immune cell-EVs significantly prolonged graft survival and improve renal function but not MSC-EVs. CONCLUSIONS: EVs are promising candidates to suppress allograft rejection and improve kidney transplant outcome. Immune cell-EVs showed their superiority over MSC-EVs in prolonging graft survival and improving renal function. For interpretation of the outcomes, additional studies are needed to validate these findings.