Measurement of precursor miRNA in exosomes from human ESC-derived mesenchymal stem cells

Mesenchymal Stem Cell-Derived Exosomes: Applications in Regenerative Medicine

Exosomes are a type of extracellular vesicles, produced within multivesicular bodies, that are then released into the extracellular space through a merging of the multivesicular body with the plasma membrane. These vesicles are secreted by almost all cell types to aid in a vast array of cellular functions, including intercellular communication, cell differentiation and proliferation, angiogenesis, stress response, and immune signaling. This ability to contribute to several distinct processes is due to the complexity of exosomes, as they carry a multitude of signaling moieties, including proteins, lipids, cell surface receptors, enzymes, cytokines, transcription factors, and nucleic acids. The favorable biological properties of exosomes including biocompatibility, stability, low toxicity, and proficient exchange of molecular cargos make exosomes prime candidates for tissue engineering and regenerative medicine. Exploring the functions and molecular payloads of exosomes can facilitate tissue regeneration therapies and provide mechanistic insight into paracrine modulation of cellular activities. In this review, we summarize the current knowledge of exosome biogenesis, composition, and isolation methods. We also discuss emerging healing properties of exosomes and exosomal cargos, such as microRNAs, in brain injuries, cardiovascular disease, and COVID-19 amongst others. Overall, this review highlights the burgeoning roles and potential applications of exosomes in regenerative medicine.

Exosomal microRNAs from mesenchymal stem/stromal cells: Biology and applications in neuroprotection

Mesenchymal stem/stromal cells (MSCs) are extensively studied as cell-therapy agents for neurological diseases. Recent studies consider exosomes secreted by MSCs as important mediators for MSCs’ neuroprotective functions. Exosomes transfer functional molecules including proteins, lipids, metabolites, DNAs, and coding and non-coding RNAs from MSCs to their target cells. Emerging evidence shows that exosomal microRNAs (miRNAs) play a key role in the neuroprotective properties of these exosomes by targeting several genes and regulating various biological processes. Multiple exosomal miRNAs have been identified to have neuroprotective effects by promoting neurogenesis, neurite remodeling and survival, and neuroplasticity. Thus, exosomal miRNAs have significant therapeutic potential for neurological disorders such as stroke, traumatic brain injury, and neuroinflammatory or neurodegenerative diseases and disorders. This review discusses the neuroprotective effects of selected miRNAs (miR-21, miR-17-92, miR-133, miR-138, miR-124, miR-30, miR146a, and miR-29b) and explores their mechanisms of action and applications for the treatment of various neurological disease and disorders. It also provides an overview of state-of-the-art bioengineering approaches for isolating exosomes, optimizing their yield and manipulating the miRNA content of their cargo to improve their therapeutic potential.

Treatment for Hepatocellular Carcinoma Is Enhanced When Norcantharidin Is Encapsulated in Exosomes Derived from Bone Marrow Mesenchymal Stem Cells

Mesenchymal stem cell-derived exosomes (MSC-Exos) have potential as drug-delivery vehicles and exhibit great promise for hepatocellular carcinoma (HCC) therapy. Here, we consider bone mesenchymal stem cell-derived exosomes (BMSC-Exos) as drug carriers to encase anticancer drug norcantharidin (NCTD) and explore their potential therapeutic effects against HCC. NCTD was loaded into purified exosomes from BMSCs via electroporation, and an in vitro drug release study showed that BMSC-Exos-NCTD provided a continuous and slow release of the drug. A series of in vitro and in vivo pharmacodynamic evaluations based on the HCC cell line HepG2 were conducted. The results showed that the BMSC-Exos-NCTD delivery system effectively promoted cellular uptake, induced cell cycle arrest, reduced tumor cell proliferation, increased apoptosis, and exerted obvious in vivo antitumor effects compared with the NCTD treatment alone, with BMSC-Exos-NCTD showing more significant antitumor effects. Furthermore, the in vivo detection results of the homing effect using the probe Cy5.5 showed that the BMSC-Exos carrier has an in situ homing effect on the tumor sites of HCC in mice. Moreover, BMSC-Exos-NCTD did not show body toxicity. Excitedly, BMSC-Exos-NCTD repaired damaged liver tissues in liver sections; specifically, the experimental effectiveness of the exosomes on the normal liver cell line L02 indicated that the damaged liver cells were repaired by the exosomes, as reflected by the increase in cellular proliferation and the inhibition of liver cell oxidation. Our results suggest that BMSC-Exos, as drug carriers with specific functions, have great potential in the HCC treatment in combination with anticancer drugs.

Extracellular Vesicle-Mediated siRNA Delivery, Protein Delivery, and CFTR Complementation in Well-Differentiated Human Airway Epithelial Cells

Extracellular vesicles (EVs) are a class of naturally occurring secreted cellular bodies that are involved in long distance cell-to-cell communication. Proteins, lipids, mRNA, and miRNA can be packaged into these vesicles and released from the cell. This information is then delivered to target cells. Since EVs are naturally adapted molecular messengers, they have emerged as an innovative, inexpensive, and robust method to deliver therapeutic cargo in vitro and in vivo. Well-differentiated primary cultures of human airway epithelial cells (HAE) are refractory to standard transfection techniques. Indeed, common strategies used to overexpress or knockdown gene expression in immortalized cell lines simply have no detectable effect in HAE. Here we use EVs to efficiently deliver siRNA or protein to HAE. Furthermore, EVs can deliver CFTR protein to cystic fibrosis donor cells and functionally correct the Cl⁻ channel defect in vitro. EV-mediated delivery of siRNA or proteins to HAE provides a powerful genetic tool in a model system that closely recapitulates the in vivo airways.

Role of cardiac progenitor cell-derived exosome-mediated microRNA-210 in cardiovascular disease

Cardiac progenitor cells are considered to be one of the most promising stem cells for heart regeneration and repair. The cardiac protective effect of CPCs is mainly achieved by reducing tissue damage and/or promoting tissue repair through a paracrine mechanism. Exosome is a factor that plays a major role in the paracrine effect of CPCs. By delivering microRNAs to target cells and regulating their functions, exosomes have shown significant beneficial effects in slowing down cardiac injury and promoting cardiac repair. Among them, miRNA-210 is an important anoxic-related miRNA derived from CPCs exosomes, which has great cardiac protective effect of inhibiting myocardial cell apoptosis, promoting angiogenesis and improving cardiac function. In addition, circulating miR-210 may be a useful biomarker for the prediction or diagnosis of related cardiovascular diseases. In this review, we briefly reviewed the mechanism of miR-210 derived from CPCs exosomes in cardiac protection in recent years.

Exosomes derived from miR-92a-3p-overexpressing human mesenchymal stem cells enhance chondrogenesis and suppress cartilage degradation via targeting WNT5A

Background

WNT5A is known to be involved in the pathogenesis of osteoarthritis. This study investigated the molecular mechanism of exosomal miR-92a-3p and WNT5A in chondrogenesis and cartilage degeneration.

Methods

Exosomal miR-92a-3p expression was assessed in vitro in a human mesenchymal stem cell (MSC) model of chondrogenesis and in normal and OA primary human chondrocytes (PHCs). MSCs and PHCs were treated with exosomes derived from MSC-miR-92a-3p (MSC-miR-92a-3p-Exos) or its antisense inhibitor (MSC-anti-miR-92a-3p-Exos), respectively. Small interfering RNAs (siRNAs) and luciferase reporter assay were used to reveal the molecular role of exosomal miR-92a-3p and WNT5A in chondrogenesis. The protective effect of exosomes in vivo was measured using Safranin-O and Fast Green staining and immunohistochemical staining.

Results

Exosomal miR-92a-3p expression was elevated in the MSC chondrogenic exosome, while it was significantly reduced in the OA chondrocyte-secreted exosome compared with normal cartilage. Treatment with MSC-miR-92a-3p-Exos promoted cartilage proliferation and matrix genes expression in MSCs and PHCs, respectively. In contrast, treatment with MSC-anti-miR-92a-3p-Exos repressed chondrogenic differentiation and reduced cartilage matrix synthesis by enhancing the expression of WNT5A. Luciferase reporter assay demonstrated that miR-92a-3p suppressed the activity of a reporter construct containing the 3’-UTR and inhibited WNT5A expression in both MSCs and PHCs. MSC-miR-92a-3p-Exos inhibit cartilage degradation in the OA mice model.

Conclusions

Our results suggest that exosomal miR-92a-3p regulates cartilage development and homeostasis by directly targeting WNT5A. This indicates that exosomal miR-92a-3p may act as a Wnt inhibitor and exhibits potential as a disease-modifying osteoarthritis drug.

Electronic supplementary material

The online version of this article (10.1186/s13287-018-1004-0) contains supplementary material, which is available to authorized users.

Stem Cell-Derived Exosome in Cardiovascular Diseases: Macro Roles of Micro Particles

The stem cell-based therapy has emerged as the promising therapeutic strategies for cardiovascular diseases (CVDs). Recently, increasing evidence suggest stem cell-derived active exosomes are important communicators among cells in the heart via delivering specific substances to the adjacent/distant target cells. These exosomes and their contents such as certain proteins, miRNAs and lncRNAs exhibit huge beneficial effects on preventing heart damage and promoting cardiac repair. More importantly, stem cell-derived exosomes are more effective and safer than stem cell transplantation. Therefore, administration of stem cell-derived exosomes will expectantly be an alternative stem cell-based therapy for the treatment of CVDs. Furthermore, modification of stem cell-derived exosomes or artificial synthesis of exosomes will be the new therapeutic tools for CVDs in the future. In addition, stem cell-derived exosomes also have been implicated in the diagnosis and prognosis of CVDs. In this review, we summarize the current advances of stem cell-derived exosome-based treatment and prognosis for CVDs, including their potential benefits, underlying mechanisms and limitations, which will provide novel insights of exosomes as a new tool in clinical therapeutic translation in the future.

Overexpression of FOXQ1 enhances anti-senescence and migration effects of human umbilical cord mesenchymal stem cells in vitro and in vivo

Mesenchymal stem cells (MSCs) are unique precursor cells characterized by active self-renewal and differentiation potential. These cells offer the advantages of ease of isolation and limited ethical issues as a resource and represent a promising cell therapy for neurodegenerative diseases. However, replicative senescence during cell culture as well as low efficiency of cell migration and differentiation after transplantation are major obstacles. In our previous study, we found that FOXQ1 binds directly to the SIRT1 promoter to regulate cellular senescence and also promotes cell proliferation and migration in many tumor cell lines. Currently, little is known about the effects of FOXQ1 on normal somatic cells. Therefore, we examine the effects of FOXQ1 on senescence and migration of MSCs. Lentiviral vector-mediated overexpression of FOXQ1 in human umbilical cord mesenchymal stem cells (hUC-MSCs) resulted in enhanced cell proliferation and viability. Furthermore, the expression of proteins and markers positively associated with senescence (p16, p21, p53) was reduced, whereas expression of proteins negatively associated with senescence (SIRT1, PCNA) was promoted. Following transplantation of hUC-MSCs overexpressing FOXQ1 in an animal model of Alzheimer's disease (APPV717I transgenic mice) resulted in amelioration of the effects of Alzheimer's disease (AD) on cognitive function and pathological senescence accompanied the increased numbers of hUC-MSCs in the AD brain. In conclusion, FOXQ1 overexpression promotes anti-senescence and migration of hUC-MSCs in vitro and in vivo. These findings also suggest that this strategy may contribute to optimization of the efficiency of stem cell therapy.

Exosomes from Glioma-Associated Mesenchymal Stem Cells Increase the Tumorigenicity of Glioma Stem-like Cells via Transfer of miR-1587

Tumor-stromal communications impact tumorigenesis in ways that are incompletely understood. Here, we show that glioma-associated human mesenchymal stem cells (GA-hMSC), a newly identified stromal component of glioblastoma, release exosomes that increase the proliferation and clonogenicity of tumor-initiating glioma stem-like cells (GSC). This event leads to a significantly greater tumor burden and decreased host survival compared with untreated GSCs in orthotopic xenografts. Analysis of the exosomal content identified miR-1587 as a mediator of the exosomal effects on GSCs, in part via downregulation of the tumor-suppressive nuclear receptor corepressor NCOR1. Our results illuminate the tumor-supporting role for GA-hMSCs by identifying GA-hMSC-derived exosomes in the intercellular transfer of specific miRNA that enhance the aggressiveness of glioblastoma. Cancer Res; 77(21); 5808-19. ©2017 AACR.

Role of stem cell-derived exosomes in cancer

Exosomes are small, extracellular membrane- enclosed vesicles that contain a variety of molecules, including proteins, DNA, mRNA and non-coding RNA; these vesicles have been defined as new tools for intercellular communication between cells. Numerous types of cells, including stem cells, secrete exosomes into the extracellular environment, and are significant communicators in the tumor microenvironment. Stem cells are a unique cell population defined by their ability to indefinitely self-renew, differentiate into a variety of cell lines, and form clonal cell populations. Stem cells also secrete large amounts of exosomes, which have demonstrated great potential in a variety of diseases. Increasing evidence has revealed that the mechanism of interaction between stem cells and human tumor cells involves the exchange of biological material through exosomes. In this review, the latest developments in the role of stem cell-derived exosomes in cancer are highlighted.

Circulating osteocyte-derived exosomes contain miRNAs which are enriched in exosomes from MLO-Y4 cells

Signaling molecules produced by osteocytes have been proposed to serve as soluble factors that contribute to bone remodeling, as well as to homeostasis of other organs. However, to the best of our knowledge, there are currently no studies investigating the role of osteocyte-secreted exosomes. In the present study, ablation of osteocytes in mice [osteocyte-less (OL)] was used to examine the microRNA (miRNA) levels of plasma-circulating exosomes. In order to investigate the function of osteocyte-secreted exosomes, exosomes derived from MLO-Y4 cells were extracted and their miRNA expression levels were examined using miRNA array analysis and deep sequencing. Comparison of miRNA expression levels between plasma exosomes from OL mouse plasma and MLO-Y4-derived exosomes revealed that decreases in the number of miRNAs from exosomes circulating in the OL mouse plasma may be caused by a decrease in secretion of exosomes from osteocytes. These results suggest that osteocytes secrete exosomes containing characterized miRNAs and then circulate in the blood, and may thus transfer their components, including miRNAs, to recipient cells where they function as signaling molecules in other organs and/or tissues to regulate biological responses.

Mesenchymal stromal cell-based therapy: Regulatory and translational aspects in gastroenterology

The past decade has witnessed an outstanding scientific production focused towards the possible clinical applications of mesenchymal stromal cells (MSCs) in autoimmune and chronic inflammatory diseases. This raised the need of novel standards to adequately address quality, efficacy and safety issues of this advanced therapy. The development of a streamlined regulation is currently hampered by the complexity of analyzing dynamic biological entities rather than chemicals. Although numerous pieces of evidence show efficacy in reducing intestinal inflammation, some inconsistencies between the mechanisms of action of rodent vs human MSCs suggest caution before assigning translational value to preclinical studies. Preliminary evidence from clinical trials showed efficacy of MSCs in the treatment of fistulizing Crohn’s disease (CD), and preparations of heterologous MSCs for CD treatment are currently tested in ongoing clinical trials. However, safety issues, especially in long-term treatment, still require solid clinical data. In this regard, standardized guidelines for appropriate dosing and methods of infusion could enhance the likelihood to predict more accurately the number of responders and the duration of remission periods. In addition, elucidating MSC mechanisms of action could lead to novel and more reliable formulations such as those derived from the MSCs themselves (e.g., supernatants).

Activated Stat5 trafficking Via Endothelial Cell-derived Extracellular Vesicles Controls IL-3 Pro-angiogenic Paracrine Action

Soluble factors and cell-derived extracellular vesicles (EVs) control vascular cell fate during inflammation. The present study investigates the impact of Interleukin 3 (IL-3) on EV release by endothelial cells (ECs), the mechanisms involved in EV release and paracrine actions. We found that IL-3 increases EV release, which is prevented by IL-3Ralpha blockade. EVs released upon IL-3 stimulation were able to induce pro-angiogenic signals as shown by chromatin immunoprecipitation (ChIP) assay performed on the promoter region of cyclin D1 and tridimensional tube-like structure formation. We herein demonstrate that these effects rely on the transfer of miR-126-3p, pre-miR-126 and, more importantly, of activated signal transduction and activator of transcription 5 (pSTAT5) from IL-3-EV cargo into recipient ECs. We show, using the dominant negative form (ΔN)STAT5 and an activated STAT5 (1*6STAT5) constructs, that STAT5 drives IL-3-mediated EV release, miR-126-3p and pSTAT5 content. Finally, using EVs recovered from ΔNSTAT5 expressing ECs, we provide evidence that miR-126-3p and pSTAT5 trafficking is relevant for IL-3-mediated paracrine pro-angiogenic signals. These results indicate that IL-3 regulates EC-EV release, cargo and IL-3 angiogenic paracrine action via STAT5. Moreover, these results provide evidence that EC-derived IL-3-EVs can serve as pro-angiogenic clinical delivery wound healing devices.

Investigation of Content, Stoichiometry and Transfer of miRNA from Human Neural Stem Cell Line Derived Exosomes

Exosomes are small (30–100 nm) membrane vesicles secreted by a variety of cell types and only recently have emerged as a new avenue for cell-to-cell communication. They are natural shuttles of RNA and protein cargo, making them attractive as potential therapeutic delivery vehicles. MicroRNAs (miRNAs) are short non-coding RNAs which regulate biological processes and can be found in exosomes. Here we characterized the miRNA contents of exosomes derived from human neural stem cells (hNSCs). Our investigated hNSC line is a clonal, conditionally immortalized cell line, compliant with good manufacturing practice (GMP), and in clinical trials for stroke and critical limb ischemia in the UK (clinicaltrials.gov: NCT01151124, NCT02117635, and NCT01916369). By using next generation sequencing (NGS) technology we identified the presence of a variety of miRNAs in both exosomal and cellular preparations. Many of these miRNAs were enriched in exosomes indicating that cells specifically sort them for extracellular release. Although exosomes have been proven to contain miRNAs, the copy number quantification per exosome of a given miRNA remains unclear. Herein we quantified by real-time PCR a highly shuttled exosomal miRNA subtype (hsa-miR-1246) in order to assess its stoichiometry per exosome. Furthermore, we utilized an in vitro system to confirm its functional transfer by measuring the reduction in luciferase expression using a 3’ untranslated region dual luciferase reporter assay. In summary, NGS analysis allowed the identification of a unique set of hNSC derived exosomal miRNAs. Stoichiometry and functional transfer analysis of one of the most abundant identified miRNA, hsa-miR-1246, were measured to support biological relevance of exosomal miRNA delivery.

The potential use of mesenchymal stem cells in stroke therapy--From bench to bedside

Stroke is the second main cause of morbidity and mortality worldwide. The rationale for the use of mesenchymal stem cells (MSCs) in stroke is based on the capacity of MSCs to secrete a large variety of bioactive molecules such as growth factors, cytokines and chemokines leading to reduction of inflammation, increased neurogenesis from the germinative niches of central nervous system, increased angiogenesis, effects on astrocytes, oligodendrocytes and axons. This review presents the data derived from experimental studies and the evidence available from clinical trials about the use of MSCs in stroke therapy.

Exosomes/miRNAs as mediating cell-based therapy of stroke

Cell-based therapy, e.g., multipotent mesenchymal stromal cell (MSC) treatment, shows promise for the treatment of various diseases. The strong paracrine capacity of these cells and not their differentiation capacity, is the principal mechanism of therapeutic action. MSCs robustly release exosomes, membrane vesicles (~30–100 nm) originally derived in endosomes as intraluminal vesicles, which contain various molecular constituents including proteins and RNAs from maternal cells. Contained among these constituents, are small non-coding RNA molecules, microRNAs (miRNAs), which play a key role in mediating biological function due to their prominent role in gene regulation. The release as well as the content of the MSC generated exosomes are modified by environmental conditions. Via exosomes, MSCs transfer their therapeutic factors, especially miRNAs, to recipient cells, and therein alter gene expression and thereby promote therapeutic response. The present review focuses on the paracrine mechanism of MSC exosomes, and the regulation and transfer of exosome content, especially the packaging and transfer of miRNAs which enhance tissue repair and functional recovery. Perspectives on the developing role of MSC mediated transfer of exosomes as a therapeutic approach will also be discussed.

The Regenerative Role of the Fetal and Adult Stem Cell Secretome

For a long time, the stem cell regenerative paradigm has been based on the assumption that progenitor cells play a critical role in tissue repair by means of their plasticity and differentiation potential. However, recent works suggest that the mechanism underlying the benefits of stem cell transplantation might relate to a paracrine modulatory effect rather than the replacement of affected cells at the site of injury. Therefore, mounting evidence that stem cells may act as a reservoir of trophic signals released to modulate the surrounding tissue has led to a paradigm shift in regenerative medicine. Attention has been shifted from analysis of the stem cell genome to understanding the stem cell “secretome”, which is represented by the growth factors, cytokines and chemokines produced through paracrine secretion. Insights into paracrine-mediated repair support a new approach in regenerative medicine and the isolation and administration of specific stem cell-derived paracrine factors may represent an extremely promising strategy, introducing paracrine-based therapy as a novel and feasible clinical application. In this review, we will discuss the regenerative potential of fetal and adult stem cells, with particular attention to their secretome.