Mesenchymal Stromal Cells Extracellular Vesicles Research Articles

Mesenchymal stromal cell extracellular vesicles improve lung development in mechanically ventilated preterm lambs.

Novel therapies are needed for bronchopulmonary dysplasia (BPD) because no effective treatment exists. Mesenchymal stromal cell extracellular vesicles (MSC-sEVs) have therapeutic efficacy in a mouse pup neonatal hyperoxia BPD model. We tested the hypothesis that MSC-sEVs will improve lung functional and structural development in mechanically ventilated preterm lambs. Preterm lambs (~129d; equivalent to human lung development at ~28w gestation) were exposed to antenatal steroids, surfactant, caffeine citrate, and supported by mechanical ventilation for 6-7d. Lambs were randomized to blinded treatment with either MSC-sEVs (human bone marrow MSC-derived; 2x1011 particles iv; n=8; 4F/4M) or vehicle control (saline iv; 4F/4M). Treatment was at 6 and 78 hours post-delivery. Physiological targets were pulse oximetry O2 saturation 90-94% (PaO2 60-90 mmHg), PaCO2 45-60 mmHg (pH 7.25-7.35), and tidal volume 5-7 mL/Kg. MSC-sEVs-treated preterm lambs tolerated enteral feedings and maintained weight compared to the vehicle control group. Respiratory severity score, oxygenation index, A-a gradient, distal airspace wall thickness, and smooth muscle thickness around terminal bronchioles and pulmonary arterioles were lower (*) for the MSC-sEVs group versus the vehicle controls. S/F ratio, radial alveolar count, secondary septal volume density, alveolar capillary surface density, and protein abundance of VEGF-R2 were higher (*) for the MSC-sEVs versus the vehicle control group. MSC-sEVs improved respiratory system physiology and alveolar formation in mechanically ventilated preterm lambs. MSC-sEVs may be an effective and safe therapy for appropriate functional and structural development of the lung in preterm infants who require mechanical ventilation and are at-risk of developing BPD.

Mesenchymal stromal cells secretome restores bioenergetic and redox homeostasis in human proximal tubule cells after ischemic injury

BackgroundIschemia/reperfusion injury is the leading cause of acute kidney injury (AKI). The current standard of care focuses on supporting kidney function, stating the need for more efficient and targeted therapies to enhance repair. Mesenchymal stromal cells (MSCs) and their secretome, either as conditioned medium (CM) or extracellular vesicles (EVs), have emerged as promising options for regenerative therapy; however, their full potential in treating AKI remains unknown.MethodsIn this study, we employed an in vitro model of chemically induced ischemia using antimycin A combined with 2-deoxy-d-glucose to induce ischemic injury in proximal tubule epithelial cells. Afterwards we evaluated the effects of MSC secretome, CM or EVs obtained from adipose tissue, bone marrow, and umbilical cord, on ameliorating the detrimental effects of ischemia. To assess the damage and treatment outcomes, we analyzed cell morphology, mitochondrial health parameters (mitochondrial activity, ATP production, mass and membrane potential), and overall cell metabolism by metabolomics.ResultsOur findings show that ischemic injury caused cytoskeletal changes confirmed by disruption of the F-actin network, energetic imbalance as revealed by a 50% decrease in the oxygen consumption rate, increased oxidative stress, mitochondrial dysfunction, and reduced cell metabolism. Upon treatment with MSC secretome, the morphological derangements were partly restored and ATP production increased by 40–50%, with umbilical cord-derived EVs being most effective. Furthermore, MSC treatment led to phenotype restoration as indicated by an increase in cell bioenergetics, including increased levels of glycolysis intermediates, as well as an accumulation of antioxidant metabolites.ConclusionOur in vitro model effectively replicated the in vivo-like morphological and molecular changes observed during ischemic injury. Additionally, treatment with MSC secretome ameliorated proximal tubule damage, highlighting its potential as a viable therapeutic option for targeting AKI.

Mesenchymal stromal cell extracellular vesicles: A possible strategy for prevention of preterm birth

The leading cause of infant morbidity and mortality is preterm birth (PTB) which has different etiologies such as infection. Mostly through the inflammatory pathways, infection could trigger preterm labor (PTL) and cause PTB. In this condition, using antibiotics are encouraged but in absence of bacterial infections antibiotics themselves might cause an inflammatory state and therefore lead to PTL. Mesenchymal stromal cells (MSCs) have been used in many trials due to their potent anti-inflammatory and immunomodulatory activity. These effects have been known to be caused by their secreted extracellular vesicles (EVs) which also, they have shown the same effect in the performed clinical studies. Also, MSC EVs have been shown to affect bronchopulmonary dysplasia which is among the consequences of PTB. All and all, we suggest further animal and human studies on the potential of MSC EVs for the prevention of PTB.

Impact of storage conditions and duration on function of native and cargo-loaded mesenchymal stromal cell extracellular vesicles

Background aimsAs evidenced by ongoing clinical trials and increased activity in the commercial sector, extracellular vesicle (EV)-based therapies have begun the transition from bench to bedside. As this progression continues, one critical aspect of EV clinical translation is understanding the effects of storage and transport conditions. Several studies have assessed the impact of storage on EV characteristics such as morphology, uptake and component content, but effects of storage duration and temperature on EV functional bioactivity and, especially, loaded cargo are rarely reported. MethodsThe authors assessed EV outcomes following storage at different temperatures (room temperature, 4°C, –20°C, –80°C) for various durations as well as after lyophilization. ResultsMesenchymal stromal cell (MSC) EVs were observed to retain key aspects of their bioactivity (pro-vascularization, anti-inflammation) for up to 4–6 weeks at –20°C and –80°C and after lyophilization. Furthermore, via in vitro assays and an in vivo wound healing model, these same storage conditions were also demonstrated to enable preservation of the functionality of loaded microRNA and long non-coding RNA cargo in MSC EVs. ConclusionsThese findings extend the current understanding of how EV therapeutic potential is impacted by storage conditions and may inform best practices for handling and storing MSC EVs for both basic research and translational purposes.

Lung Extracellular Matrix Hydrogels-Derived Vesicles Contribute to Epithelial Lung Repair.

The use of physiomimetic decellularized extracellular matrix-derived hydrogels is attracting interest since they can modulate the therapeutic capacity of numerous cell types, including mesenchymal stromal cells (MSCs). Remarkably, extracellular vesicles (EVs) derived from MSCs display similar functions as their parental cells, mitigating tissue damage in lung diseases. However, recent data have shown that ECM-derived hydrogels could release other resident vesicles similar to EVs. Here, we aim to better understand the contribution of EVs and ECM-vesicles released from MSCs and/or lung-derived hydrogel (L-HG) in lung repair by using an in vitro lung injury model. L-HG derived-vesicles and MSCs EVs cultured either in L-HG or conventional plates were isolated and characterized. The therapeutic capacity of vesicles obtained from each experimental condition was tested by using an alveolar epithelial wound-healing assay. The number of ECM-vesicles released from acellular L-HG was 10-fold greater than EVs from conventional MSCs cell culture revealing that L-HG is an important source of bioactive vesicles. MSCs-derived EVs and L-HG vesicles have similar therapeutic capacity in lung repair. However, when wound closure rate was normalized by total proteins, the MSCs-derived EVs shows higher therapeutic potential to those released by L-HG. The EVs released from L-HG must be considered when HG is used as substrate for cell culture and EVs isolation.

Mesenchymal stromal cells-derived extracellular vesicles reprogramme macrophages in ARDS models through the miR-181a-5p-PTEN-pSTAT5-SOCS1 axis

RationaleA better understanding of the mechanism of action of mesenchymal stromal cells (MSCs) and their extracellular vesicles (EVs) is needed to support their use as novel therapies for acute respiratory...

Pulmonary and Neurologic Effects of Mesenchymal Stromal Cell Extracellular Vesicles in a Multifactorial Lung Injury Model.

Rationale: Bronchopulmonary dysplasia, a chronic respiratory condition originating from preterm birth, is associated with abnormal neurodevelopment. Currently, there is an absence of effective therapies for bronchopulmonary dysplasia and its associated brain injury. In preclinical trials, mesenchymal stromal cell therapies demonstrate promise as a therapeutic alternative for bronchopulmonary dysplasia. Objectives: To investigate whether a multifactorial neonatal mouse model of lung injury perturbs neural progenitor cell function and to assess the ability of human umbilical cord-derived mesenchymal stromal cell extracellular vesicles to mitigate pulmonary and neurologic injury. Methods: Mice at Postnatal Day 7 or 8 were injected intraperitoneally with LPS and ventilated with 40% oxygen at Postnatal Day 9 or 10 for 8 hours. Treated animals received umbilical cord-mesenchymal stromal cell-derived extracellular vesicles intratracheally preceding ventilation. Lung morphology, vascularity, and inflammation were quantified. Neural progenitor cells were isolated from the subventricular zone and hippocampus and assessed for self-renewal, invitro differentiation ability, and transcriptional profiles. Measurements and Main Results: The multifactorial lung injury model produced alveolar and vascular rarefaction mimicking bronchopulmonary dysplasia. Neural progenitor cells from lung injury mice showed reduced neurosphere and oligodendrocyte formation, as well as inflammatory transcriptional signatures. Mice treated with mesenchymal stromal cell extracellular vesicles showed significant improvement in lung architecture, vessel formation, and inflammatory modulation. In addition, we observed significantly increased invitro neurosphere formation and altered neural progenitor cell transcriptional signatures. Conclusions: Our multifactorial lung injury model impairs neural progenitor cell function. Observed pulmonary and neurologic alterations are mitigated by intratracheal treatment with mesenchymal stromal cell-derived extracellular vesicles.

Abu Khaled Muhammed Akramul Haq

<h3>Rationale</h3> A better understanding of the mechanism of action of mesenchymal stromal cells (MSCs) and their extracellular vesicles (EVs) is needed to support their use as novel therapies for acute...

Clinical translation of mesenchymal stromal cell extracellular vesicles: Considerations on scientific rationale and production requisites.

The present paper is a commentary to ‘Identification and characterization of hADSC‐derived exosome proteins from different isolation methods’ (Huang et al. 2021; 10.1111/jcmm.16775). Given the enthusiasm for the potential of mesenchymal stromal cell‐derived extracellular vesicles (MSC‐EVs), some considerations deserve attention as they move through successive stages of research and application into humans. We herein remark the prerequisite of generating that evidence ensuring a high consistency in safety, composition and biological activity of the intended MSC‐EV preparations, and the suitability of disparate isolation techniques to produce efficacious EV preparations and fulfil requirements for standardized clinical‐grade biomanufacturing.

Mesenchymal stromal cell extracellular vesicles as therapy for acute and chronic respiratory diseases: A meta-analysis.

Preclinical studies suggest mesenchymal stromal cell extracellular vesicles (MSC‐EVs) reduce inflammation and improve organ function in lung diseases; however, an objective analysis of all available data is needed prior to translation. Using rigorous meta‐research methods, we determined the effectiveness of MSC‐EVs for preclinical respiratory diseases and identified experimental conditions that may further refine this therapy. A systematic search of MEDLINE/Embase identified 1167 records. After screening, 52 articles were included for data extraction and evaluated for risk of bias and quality of reporting in study design. A random effects meta‐analysis was conducted for acute lung injury (ALI; N = 23), bronchopulmonary dysplasia (BPD; N = 8) and pulmonary arterial hypertension (PAH; N = 7). Subgroup analyses identified EV methods/characteristics that may be associated with improved efficacy. Data is presented as standardized mean differences (SMD) or risk ratios (RR) with 95% confidence intervals (CI). For ALI, MSC‐EVs markedly reduced lung injury (SMD ‐4.33, CI ‐5.73 to ‐2.92), vascular permeability (SMD ‐2.43, CI ‐3.05 to ‐1.82), and mortality (RR 0.39, CI 0.22 to 0.68). Small EVs were more consistently effective than large EVs whereas no differences were observed between tissue sources, immunocompatibility or isolation techniques. For BPD, alveolarization was improved by MSC‐EVs (SMD ‐1.45, CI ‐2.08 to ‐0.82) with small EVs more consistently beneficial then small/large EVs. In PAH, right ventricular systolic pressure (SMD ‐4.16, CI ‐5.68 to ‐2.64) and hypertrophy (SMD ‐2.80, CI ‐3.68 to ‐1.91) were significantly attenuated by EVs. In BPD and PAH, EVs isolated by ultracentrifugation demonstrated therapeutic benefit whereas tangential flow filtration (N = 2) displayed minimal efficacy. Lastly, risk of bias and quality of reporting for experimental design were consistently unclear across all studies. Our findings demonstrate clear potential of MSC‐EVs to be developed as therapy for acute and chronic lung diseases. However, greater transparency in research design and direct comparisons of isolation technique and EV subtypes are needed to generate robust evidence to guide clinical translation.Protocol Registration: PROSPERO CRD42020145334

Characterization of extracellular vesicles derived from mesenchymal stromal cells by surface-enhanced Raman spectroscopy.

Extracellular vesicles (EVs) are secreted by all cells into bodily fluids and play an important role in intercellular communication through the transfer of proteins and RNA. There is evidence that EVs specifically released from mesenchymal stromal cells (MSCs) are potent cell-free regenerative agents. However, for MSC EVs to be used in therapeutic practices, there must be a standardized and reproducible method for their characterization. The detection and characterization of EVs are a challenge due to their nanoscale size as well as their molecular heterogeneity. To address this challenge, we have fabricated gold nanohole arrays of varying sizes and shapes by electron beam lithography. These platforms have the dual purpose of trapping single EVs and enhancing their vibrational signature in surface-enhanced Raman spectroscopy (SERS). In this paper, we report SERS spectra for MSC EVs derived from pancreatic tissue (Panc-MSC) and bone marrow (BM-MSC). Using principal component analysis (PCA), we determined that the main compositional differences between these two groups are found at 1236, 761, and 1528 cm-1, corresponding to amide III, tryptophan, and an in-plane -C=C- vibration, respectively. We additionally explored several machine learning approaches to distinguish between BM- and Panc-MSC EVs and achieved 89 % accuracy, 89 % sensitivity, and 88 % specificity using logistic regression.

Comparison of miRNA cargo in human adipose-tissue vs. amniotic-membrane derived mesenchymal stromal cells extracellular vesicles for osteoarthritis treatment

Extracellular Vesicles and Circulating Nucleic Acids is an open access journal, focusing on extracellular vesicles and circulating nucleic acids including DNA, RNA, and miRNA and their therapeutic use.

Mesenchymal stromal cell extracellular vesicles rescue mitochondrial dysfunction and improve barrier integrity in clinically relevant models of ARDS.

Alveolar epithelial–capillary barrier disruption is a hallmark of acute respiratory distress syndrome (ARDS). Contribution of mitochondrial dysfunction to the compromised alveolar-capillary barrier in ARDS remains unclear. Mesenchymal stromal cells-derived extracellular vesicles (MSC-EVs) are considered as a cell-free therapy for ARDS. Mitochondrial transfer was shown to be important for the therapeutic effects of MSCs and MSC-EVs. Here we investigated the contribution of mitochondrial dysfunction to the injury of alveolar epithelial and endothelial barriers in ARDS and the ability of MSC-EVs to modulate alveolar–capillary barrier integrity through mitochondrial transfer.Primary human small airway epithelial and pulmonary microvascular endothelial cells and human precision cut lung slices (PCLSs) were stimulated with endotoxin or plasma samples from patients with ARDS and treated with MSC-EVs, barrier properties and mitochondrial functions were evaluated. Lipopolysaccharide (LPS)-injured mice were treated with MSC-EVs and degree of lung injury and mitochondrial respiration of the lung tissue were assessed.Inflammatory stimulation resulted in increased permeability coupled with pronounced mitochondrial dysfunction in both types of primary cells and PCLSs. Extracellular vesicles derived from normal MSCs restored barrier integrity and normal levels of oxidative phosphorylation while an extracellular vesicles preparation which did not contain mitochondria was not effective. In vivo, presence of mitochondria was critical for extracellular vesicles ability to reduce lung injury and restore mitochondrial respiration in the lung tissue.In the ARDS environment, MSC-EVs improve alveolar–capillary barrier properties through restoration of mitochondrial functions at least partially via mitochondrial transfer.

Interferon-γ and Hypoxia Priming Have Limited Effect on the miRNA Landscape of Human Mesenchymal Stromal Cells-Derived Extracellular Vesicles.

Mesenchymal stromal cell (MSC)-based cell therapy has received great interest in regenerative medicine. Priming the cells during the culture phase can improve their efficacy and/or survival after injection. The literature suggests that MSC extracellular vesicles (EV) can recapitulate a substantial part of the beneficial effects of the cells they originate from, and that micro-RNAs (miRNAs) are important players in EV biological action. Here, our aim was to determine if two classical priming methods of MSC, interferon-gamma (IFNγ) and hypoxia (HYP), could modify their EV miRNA content. Human bone marrow MSCs (BM-MSCs) from five healthy donors were cultured with IFNγ or in HYP or in control (CONT) conditions. The conditioned media were collected after 48 h in serum-free condition and EV were isolated by ultracentrifugation. Total RNA was isolated, pools of CONT, IFN, and HYP cDNA were prepared, and a miRNA profiling was performed using RT-qPCR. Then, miRNAs were selected based on their detectability and measured on each individual EV sample. Priming had no effect on EV amount or size distribution. A set of 81 miRNAs was detected in at least one of the pools of EVs. They were measured on each individual sample; 41 miRNAs were detected in all samples. The principal component analysis (PCA) failed to discriminate the groups. HYP induced a significant decrease in EV hsa-miR-34a-3p content and IFN induced a significant increase in five miRNAs (hsa-miR-25-3p, hsa-miR-106a-5p, hsa-miR-126-3p, hsa-miR-451a, and hsa-miR-665). Taken together, we found only limited alterations in the miRNA landscape of MSC EV with a high inter-individual variability.

Human Adipose Tissue-Derived Stromal Cells Suppress Human, but Not Murine Lymphocyte Proliferation, via Indoleamine 2,3-Dioxygenase Activity.

Over recent years, mesenchymal stromal cells (MSC) have gained immense attraction in immunotherapy, regenerative medicine and tissue engineering. MSC microenvironment modulation occurs through synergy of direct cell–cell contact, and secreted soluble factors and extracellular vesicles (EV). MSC-derived EV have been suggested as cell-free immunomodulatory alternative to MSC; however, previous findings have challenged this. Furthermore, recent data suggest that evaluating the mechanism of action of human MSC (hMSC) in animal models might promote adverse immune reactions or lack of functionality due to xeno-incompatibilities. In this study, we first assessed the immunomodulatory strength of different human MSC sources on in vitro stimulated T cells and compared this to interferon-gamma (IFNγ) primed MSC conditioned medium (CM) and EV. Second, we addressed the main molecular mechanisms, and third, we assessed the MSC in vitro immunosuppressive effect across interspecies barriers. We identified human adipose tissue-derived stromal cells (ASC) with strongest immunomodulatory strength, followed by bone marrow (BM) and cord blood-derived MSC (CB). Whilst CM from primed ASC managed to exert analogous effects as their cellular counterpart, EV derived thereof did not, reproducing previous findings. IFNγ-induced indoleamine 2,3-dioxygenase (IDO) activity was identified as key mechanism to suppress human lymphocyte proliferation, as in the presence of the IDO inhibitor epacadostat (Epac) a stimulation of proliferation was seen. In addition, we revealed MSC immunosuppressive effects to be species-specific, because human cells failed to suppress murine lymphocyte proliferation. In summary, ASC were the strongest immunomodulators with the IDO-kynurenine pathway being key within the human system. Importantly, the in vitro lack of interspecies immunomodulatory strength suggests that preclinical data need to be carefully interpreted especially when considering a possible translation to clinical field.

Modulation of thymic architecture and T cell function by Mesenchymal stromal cell extracellular vesicles in a model of neonatal hyperoxia

Abstract Therapies based on mesenchymal stem/stromal cell extracellular vesicles (MEx) have shown promise in experimental models of bronchopulmonary dysplasia (BPD), a disease of disrupted lung development that can result from neonatal exposure to hyperoxia. The effects of oxygen exposure on other developing organs in the neonatal period remain poorly understood and whether MEx treatment may modify these responses is not known. Our research aimed at understanding the effects of neonatal exposure to hyperoxia and the immunomodulatory properties of MEx on thymic architecture and T cell development. Using a mouse model of neonatal hyperoxia, we showed that, in addition to lung injury resulting in BPD, there was involution of the thymic medulla with altered T cell function. Administration of a single dose of MEx resulted in preservation of thymic architecture, and restoration of normal thymic function through modulation of the thymic medullary antigen presentation network and T cell phenotypes. Consequently, MEx reinstated the mechanisms of thymic-driven central tolerance that are perturbed upon hyperoxia exposure, as demonstrated by increased FoxP3+ regulatory T cell generation and decreased T cell autoreactivity. Overall, our study demonstrates that MEx represent a promising cell-free therapeutic option to restore thymic architecture and ensure the development of central tolerance by preventing thymic injury associated with neonatal hyperoxia exposure.

Extracellular Vesicles isolated from Mesenchymal Stromal Cells Modulate CD4+ T Lymphocytes Toward a Regulatory Profile.

Mesenchymal stromal cells (MSCs) can generate immunological tolerance due to their regulatory activity in many immune cells. Extracellular vesicles (EVs) release is a pivotal mechanism by which MSCs exert their actions. In this study, we evaluate whether mesenchymal stromal cell extracellular vesicles (MSC-EVs) can modulate T cell response. MSCs were expanded and EVs were obtained by differential ultracentrifugation of the supernatant. The incorporation of MSC-EVs by T cells was detected by confocal microscopy. Expression of surface markers was detected by flow cytometry or CytoFLEX and cytokines were detected by RT-PCR, FACS and confocal microscopy and a miRNA PCR array was performed. We demonstrated that MSC-EVs were incorporated by lymphocytes in vitro and decreased T cell proliferation and Th1 differentiation. Interestingly, in Th1 polarization, MSC-EVs increased Foxp3 expression and generated a subpopulation of IFN-γ+/Foxp3+T cells with suppressive capacity. A differential expression profile of miRNAs in MSC-EVs-treated Th1 cells was seen, and also a modulation of one of their target genes, TGFbR2. MSC-EVs altered the metabolism of Th1-differentiated T cells, suggesting the involvement of the TGF-β pathway in this metabolic modulation. The addition of MSC-EVs in vivo, in an OVA immunization model, generated cells Foxp3+. Thus, our findings suggest that MSC-EVs are able to specifically modulate activated T cells at an alternative regulatory profile by miRNAs and metabolism shifting.

Human Mesenchymal Stromal Cell-Derived Extracellular Vesicles Improve Liver Regeneration After Ischemia Reperfusion Injury in Mice.

Hepatic ischemia reperfusion injury (IRI) remains a major obstacle in liver resection and transplantation surgery, especially in diseased organs. Human mesenchymal stromal cells (MSCs) are reported to acutely alleviate hepatic IRI in mice by releasing bioactive membrane-enclosed extracellular vesicles (EVs), but the long-term effects of MSC-derived EV on hepatic IRI are unknown. Given the considerable differentiation capacity of fibroblasts (FBs) during wound healing and their morphological similarities with MSC, the present study aimed to investigate the potential of these two cell types and their cell-derived EV in attenuating liver damage after IRI. EVs were isolated and purified from the supernatant of MSC and FB cultures and, subsequently, characterized by electron microscopy, nanoparticle tracking analysis, and western blot. Liver injury and organ regeneration in a murine in vivo model of IRI were assessed by serum transaminase levels, histopathology, and immunohistochemistry. Changes in expression of inflammation-associated genes within liver tissue were evaluated by reverse transcriptase quantitative polymerase chain reaction. MSC, MSC-derived EV, FB, and FB-derived EV were systemically administered before hepatic IRI. We found that MSC and MSC-derived EV decreased serum transaminase levels, reduced hepatic necrosis, increased the amount of Ki67-positive hepatocytes, and repressed the transcription of inflammation-associated genes. Although they had no impact on organ damage, FB and FB-derived EV showed some regenerative potential in the late phase of hepatic IRI. Compared to FB, MSC and their derived EV had a stronger potential to attenuate liver damage and improve organ regeneration after hepatic IRI. These results suggest that the key therapeutic factors are located within EV.

Mesenchymal stromal cell-derived extracellular vesicles for regenerative therapy and immune modulation: Progress and challenges toward clinical application.

Extracellular vesicles (EVs) derived from mesenchymal stromal cells (MSCs) have emerged as a promising form of regenerative therapy and immune modulation. Fundamental advances in our understanding of MSCs and EVs have allowed these fields to merge and create potential cell‐free therapy options that are cell‐based. EVs contain active cargo including proteins, microRNA, and mRNA species that can impact signaling responses in target cells to modify inflammatory and repair responses. Increasing numbers of preclinical studies in animals with various types of injury models have been published that demonstrate the potential impact of MSC‐EV therapy. Although the emergence of registered clinical protocols suggests translation to clinical application has already begun, several barriers to more widespread clinical adoption remain. In this review, we highlight the progress made in MSC‐derived small EV‐based therapy by summarizing aspects pertaining to the starting material for MSC expansion, EV production, and isolation methods, studies from preclinical models that have established a foundation of knowledge to support translation into the patient setting, and potential barriers to overcome on the path to clinical application.

Stem cell-derived extracellular vesicles inhibit and revert fibrosis progression in a mouse model of diabetic nephropathy

Extracellular vesicles (EVs) that are derived from mesenchymal stromal cells (MSCs) have been shown to reprogram injured cells by activating regenerative processes. We herein investigate the potential therapeutic effect of EVs, shed by human bone marrow MSCs and by human liver stem-like cells (HLSCs), on the progression and reversion of fibrosis in a mouse model of diabetic nephropathy, as induced by streptozotocin. After the development of nephropathy, stem cell-derived EVs were administered weekly to diabetic mice for four weeks. The stem cell-derived EV treatment, but not the fibroblast EV treatment that was used as a control, significantly ameliorated functional parameters, such as albumin/creatinine excretion, plasma creatinine and blood urea nitrogen, which are altered in diabetic mice. Moreover, the renal fibrosis that develops during diabetic nephropathy progression was significantly inhibited in stem cell EV-treated animals. A correlation was found between the down regulation of several pro-fibrotic genes in renal tissues and the anti-fibrotic effect of HLSC and MSC EVs. A comparative analysis of HLSC and MSC EV miRNA content highlighted some common and some specific patterns of miRNAs that target predicted pro-fibrotic genes. In conclusion, stem cell-derived EVs inhibit fibrosis and prevent its progression in a model of diabetes-induced chronic kidney injury.