Mesenchymal Stem Cell-Derived Extracellular Vesicles: A Potential Therapeutic Strategy for Acute Kidney Injury

Therapeutic potential of mesenchymal stem cell-derived extracellular vesicles: A focus on inflammatory bowel disease

BACKGROUND

Mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) have emerged as key regulators of intercellular communication, orchestrating essential biological processes by delivering bioactive cargoes to target cells. Available evidence suggests that MSC-EVs can mimic the functions of their parental cells, exhibiting immunomodulatory, pro-regenerative, anti-apoptotic, and antifibrotic properties. Consequently, MSC-EVs represent a cell-free therapeutic option for patients with inflammatory bowel disease (IBD), overcoming the limitations associated with cell replacement therapy, including their non-immunogenic nature, lower risk of tumourigenicity, cargo specificity and ease of manipulation and storage.

MAIN TOPICS COVERED

This review aims to provide a comprehensive examination of the therapeutic efficacy of MSC-EVs in IBD, with a focus on their mechanisms of action and potential impact on treatment outcomes. We examine the advantages of MSC-EVs over traditional therapies, discuss methods for their isolation and characterisation, and present mechanistic insights into their therapeutic effects through transcriptomic, proteomic and lipidomic analyses of MSC-EV cargoes. We also discuss available preclinical studies demonstrating that MSC-EVs reduce inflammation, promote tissue repair and restore intestinal homeostasis in IBD models, and compare these findings with those of clinical trials.

CONCLUSIONS

Finally, we highlight the potential of MSC-EVs as a novel therapy for IBD and identify challenges and opportunities associated with their translation into clinical practice.

HIGHLIGHTS

The source of mesenchymal stem cells (MSCs) strongly influences the composition and function of MSC-derived extracellular vesicles (EVs), affecting their therapeutic potential. Adipose-derived MSC-EVs, known for their immunoregulatory properties and ease of isolation, show promise as a treatment for inflammatory bowel disease (IBD). MicroRNAs are consistently present in MSC-EVs across cell types and are involved in pathways that are dysregulated in IBD, making them potential therapeutic agents. For example, miR-let-7a is associated with inhibition of apoptosis, miR-100 supports cell survival, miR-125b helps suppress pro-inflammatory cytokines and miR-20 promotes anti-inflammatory M2 macrophage polarisation. Preclinical studies in IBD models have shown that MSC-EVs reduce intestinal inflammation by suppressing pro-inflammatory mediators (e.g., TNF-α, IL-1β, IL-6) and increasing anti-inflammatory factors (e.g., IL-4, IL-10). They also promote mucosal healing and strengthen the integrity of the gut barrier, suggesting their potential to address IBD pathology.

Human bone marrow mesenchymal stem cell-derived extracellular vesicles reduce inflammation and pyroptosis in acute kidney injury via miR-223-3p/HDAC2/SNRK

OBJECTIVE

Bone marrow mesenchymal stem cell (BMSC)-derived extracellular vesicles (EVs) have been demonstrated as a potential therapeutic agent in acute kidney injury (AKI). However, little is known about the mechanisms of action of BMSC-derived EVs in AKI. Based on this, our research was designed to investigate the mechanism behind BMSC-derived EVs controlling inflammation and pyroptosis during AKI.

METHODS

Peripheral blood from AKI patients was used for detection of microRNA (miR)-223-3p, HDAC2, and SNRK expression. An AKI rat model was established, and HK-2 cell injury was induced by lipopolysaccharide (LPS) to establish a cellular model. Co-culture with BMSC-derived EVs and/or gain- and loss-of-function assays were conducted in LPS-treated HK-2 to evaluate the functions of BMSCs-EVs, miR-223-3p, HDAC2, and SNRK. AKI rats were simultaneously injected with EVs and short hairpin RNAs targeting SNRK. The interactions among miR-223-3p, HDAC2, and SNRK were evaluated by RIP, ChIP, and dual-luciferase gene reporter assays.

RESULTS

Patients with AKI had low miR-223-3p and SNRK expression and high HDAC2 expression in peripheral blood. Mechanistically, miR-223-3p targeted HDAC2 to accelerate SNRK transcription. In LPS-treated HK-2 cells, BMSCs-EVs overexpressing miR-223-3p increased cell viability and diminished cell apoptosis, KIM-1, LDH, IL-1β, IL-6, TNF-α, NLRP3, ASC, cleaved caspase-1, and IL-18 expression, and GSDMD cleavage, which was nullified by HDAC2 overexpression or SNRK silencing. In AKI rats, BMSCs-EV-shuttled miR-223-3p reduced CRE and BUN levels, apoptosis, inflammation, and pyroptosis, which was abrogated by SNRK silencing.

CONCLUSION

Conclusively, BMSC-derived EV-encapsulated miR-223-3p mitigated AKI-induced inflammation and pyroptosis by targeting HDAC2 and promoting SNRK transcription.

Tight junctions and acute kidney injury

Acute kidney injury (AKI) is characterized by a rapid reduction in kidney function caused by various etiologies. Tubular epithelial cell dysregulation plays a pivotal role in the pathogenesis of AKI. Tight junction (TJ) is the major molecular structure that connects adjacent epithelial cells and is critical in maintaining barrier function and determining the permeability of epithelia. TJ proteins are dysregulated in various types of AKI, and some reno-protective drugs can reverse TJ changes caused by insult. An in-depth understanding of TJ regulation and its causality with AKI will provide more insight to the disease pathogenesis and will shed light on the potential role of TJs to serve as novel therapeutic targets in AKI.

Dual Role of Extracellular Vesicles in Sepsis-Associated Kidney and Lung Injury

Extracellular vesicles form a complex intercellular communication network, shuttling a variety of proteins, lipids, and nucleic acids, including regulatory RNAs, such as microRNAs. Transfer of these molecules to target cells allows for the modulation of sets of genes and mediates multiple paracrine and endocrine actions. EVs exert broad pro-inflammatory, pro-oxidant, and pro-apoptotic effects in sepsis, mediating microvascular dysfunction and multiple organ damage. This deleterious role is well documented in sepsis-associated acute kidney injury and acute respiratory distress syndrome. On the other hand, protective effects of stem cell-derived extracellular vesicles have been reported in experimental models of sepsis. Stem cell-derived extracellular vesicles recapitulate beneficial cytoprotective, regenerative, and immunomodulatory properties of parental cells and have shown therapeutic effects in experimental models of sepsis with kidney and lung involvement. Extracellular vesicles are also likely to play a role in deranged kidney-lung crosstalk, a hallmark of sepsis, and may be key to a better understanding of shared mechanisms underlying multiple organ dysfunction. In this review, we analyze the state-of-the-art knowledge on the dual role of EVs in sepsis-associated kidney/lung injury and repair. PubMed library was searched from inception to July 2022, using a combination of medical subject headings (MeSH) and keywords related to EVs, sepsis, acute kidney injury (AKI), acute lung injury (ALI), and acute respiratory distress syndrome (ARDS). Key findings are summarized into two sections on detrimental and beneficial mechanisms of actions of EVs in kidney and lung injury, respectively. The role of EVs in kidney-lung crosstalk is then outlined. Efforts to expand knowledge on EVs may pave the way to employ them as prognostic biomarkers or therapeutic targets to prevent or reduce organ damage in sepsis.

Mesenchymal stem cell transplantation alleviated atherosclerosis in systemic lupus erythematosus through reducing MDSCs

Objective

The mechanism by which mesenchymal stem cell (MSC) transplantation alleviates atherosclerosis in systemic lupus erythematosus (SLE) remains elusive. In this study, we aim to explore the efficacy and mechanism of MSC in ameliorating atherosclerosis in SLE.

Methods

ApoE^−/− and Fas^−/− mice on the B6 background were cross-bred to generate SLE mice with atherosclerosis. Myeloid-derived suppressor cells (MDSCs) were sorted and quantified. The apoE^−/−Fas^−/− mice were either treated with anti-Gr antibody or injected with MDSCs. The lupus-like autoimmunity and atherosclerotic lesions were evaluated. Furthermore, the apoE^−/−Fas^−/− mice were transplanted with MSCs and lupus-like autoimmunity and atherosclerotic lesions were assessed.

Results

MDSCs in peripheral blood, spleen, draining lymph nodes increased in apoE^−/−Fas^−/− mice compared with B6 mice. Moreover, the adoptive transfer of MDSCs aggravated both atherosclerosis and SLE pathologies, whereas depleting MDSCs ameliorated those pathologies in apoE^−/−Fas^−/− mice. MSC transplantation in apoE^−/−Fas^−/− mice decreased the percentage of MDSCs, alleviated the typical atherosclerotic lesions, including atherosclerotic lesions in aortae and liver, and reduced serum cholesterol, triglyceride and low-density lipoprotein levels. MSC transplantation also reduced SLE pathologies, including splenomegaly, glomerular lesions, anti-dsDNA antibody in serum, urine protein and serum creatinine. Moreover, MSC transplantation regulated the generation and function of MDSCs through secreting prostaglandin E 2 (PGE2).

Conclusion

Taken together, these results indicated that the increased MDSCs contributed to atherosclerosis in SLE. MSC transplantation ameliorated the atherosclerosis and SLE through reducing MDSCs by secreting PGE2.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-03002-y.

Fatty Acid β-Oxidation in Kidney Diseases: Perspectives on Pathophysiological Mechanisms and Therapeutic Opportunities

The kidney is a highly metabolic organ and requires a large amount of ATP to maintain its filtration-reabsorption function, and mitochondrial fatty acid β-oxidation serves as the main source of energy to meet its functional needs. Reduced and inefficient fatty acid β-oxidation is thought to be a major mechanism contributing to kidney diseases, including acute kidney injury, chronic kidney disease and diabetic nephropathy. PPARα, AMPK, sirtuins, HIF-1, and TGF-β/SMAD3 activation have all been shown to play key roles in the regulation of fatty acid β-oxidation in kidney diseases, and restoration of fatty acid β-oxidation by modulation of these molecules can ameliorate the development of such diseases. Here, we disentangle the lipid metabolism regulation properties and potential mechanisms of mesenchymal stem cells and their extracellular vesicles, and emphasize the role of mesenchymal stem cells on lipid metabolism. This review aims to highlight the important role of fatty acid β-oxidation in the progression of kidney diseases, and to explore the fatty acid β-oxidation effects and therapeutic potential of mesenchymal stem cells for kidney diseases.

Mesenchymal Stromal Cell-Derived Extracellular Vesicles as Biological Carriers for Drug Delivery in Cancer Therapy

Cancer is the second leading cause of death worldwide, with 10.0 million cancer deaths in 2020. Despite advances in targeted therapies, some pharmacological drawbacks associated with anticancer chemo and immunotherapeutic agents include high toxicities, low bioavailability, and drug resistance. In recent years, extracellular vesicles emerged as a new promising platform for drug delivery, with the advantage of their inherent biocompatibility and specific targeting compared to artificial nanocarriers, such as liposomes. Particularly, mesenchymal stem/stromal cells were proposed as a source of extracellular vesicles for cancer therapy because of their intrinsic properties: high in vitro self-renewal and proliferation, regenerative and immunomodulatory capacities, and secretion of extracellular vesicles that mediate most of their paracrine functions. Moreover, extracellular vesicles are static and safer in comparison with mesenchymal stem/stromal cells, which can undergo genetic/epigenetic or phenotypic changes after their administration to patients. In this review, we summarize currently reported information regarding mesenchymal stem/stromal cell-derived extracellular vesicles, their proper isolation and purification techniques - from either naive or engineered mesenchymal stem/stromal cells - for their application in cancer therapy, as well as available downstream modification methods to improve their therapeutic properties. Additionally, we discuss the challenges associated with extracellular vesicles for cancer therapy, and we review some preclinical and clinical data available in the literature.

Potential Therapeutic Effect and Mechanisms of Mesenchymal Stem Cells-Extracellular Vesicles in Renal Fibrosis

Renal fibrosis (RF) is central pathological pathway for kidney diseases, with the main pathological features being the aberrant accumulation of myofibroblasts that produce accumulation of extracellular matrix in the renal interstitium and glomeruli. Acute kidney injury (AKI) and chronic kidney disease (CKD) are associated with RF. Current treatment strategies for RF are ineffective. Mesenchymal stem cells (MSCs) have been found to be able to treat organ fibrosis including RF, but they have some safety problems, such as cell rejection, carcinogenicity, and virus contamination, which limit the application of MSCs. However, current studies have found that MSCs may exert their therapeutic effect by releasing extracellular vesicles (EVs). MSC-EVs can transfer functional proteins and genetic material directly to the recipient cells. As non-cell membrane structures, MSC-EVs have the advantages of low immunogenicity, easy preservation, and artificial modification, but do not have the characteristics of self-replication and ectopic differentiation. Therefore, EVs are safer than MSCs for treatment, but might be less effective than MSCs. Recent studies have also found that MSC-EVs can improve renal function and pathological changes of RF. Thus, this review summarizes the therapeutic effect of MSC-EVs on RF and the mechanisms that have been discovered so far, so as to provide a theoretical basis for the further study of the role of MSC-EVs in treating RF diseases.

Klotho and Mesenchymal Stem Cells: A Review on Cell and Gene Therapy for Chronic Kidney Disease and Acute Kidney Disease

Chronic kidney disease (CKD) and acute kidney injury (AKI) are public health problems, and their prevalence rates have increased with the aging of the population. They are associated with the presence of comorbidities, in particular diabetes mellitus and hypertension, resulting in a high financial burden for the health system. Studies have indicated Klotho as a promising therapeutic approach for these conditions. Klotho reduces inflammation, oxidative stress and fibrosis and counter-regulates the renin-angiotensin-aldosterone system. In CKD and AKI, Klotho expression is downregulated from early stages and correlates with disease progression. Therefore, the restoration of its levels, through exogenous or endogenous pathways, has renoprotective effects. An important strategy for administering Klotho is through mesenchymal stem cells (MSCs). In summary, this review comprises in vitro and in vivo studies on the therapeutic potential of Klotho for the treatment of CKD and AKI through the administration of MSCs.

Proteomic Analysis of Exosomes Secreted from Human Alpha-1 Antitrypsin Overexpressing Mesenchymal Stromal Cells

Extracellular vesicles (EVs) mediate many therapeutic effects of stem cells during cellular therapies. Bone marrow-derived mesenchymal stromal cells (BM-MSCs) were manufactured to overexpress the human antiprotease alpha-1 antitrypsin (hAAT) and studied to compare the EV production compared to lentivirus treated control MSCs. The goal of this study was to compare protein profiles in the EVs/exosomes of control and hAAT-MSCs using unbiased, high resolution liquid chromatography and mass spectrometry to explore differences. Nanoparticle tracking analysis (NTA) showed that the particle size of the EVs from control MSCs or hAAT-MSCs ranged from 30 to 200 nm. Both MSCs and hAAT-MSCs expressed exosome-associated proteins, including CD63, CD81, and CD9. hAAT-MSCs also expressed high levels of hAAT. We next performed proteomic analysis of EVs from three healthy donor cell lines. Exosomes collected from cell supernatant were classified by GO analysis which showed proteins important to cell adhesion and extracellular matrix organization. However, there were differences between exosomes from control MSCs and hAAT-MSCs in cytokine signaling of the immune system, stem cell differentiation, and carbohydrate metabolism (p < 0.05). These results show that hAAT-MSC exosomes contain a different profile of paracrine effectors with altered immune function, impacts on MSC stemness, differentiation, and prevention of cell apoptosis and survival that could contribute to improved therapeutic functions.