Stem cells and exosomes in cardiac repair

Engineered Exosomes with Growth Differentiation Factor-15 Overexpression Enhance Cardiac Repair After Myocardial Injury

Background

Cardiac repair remains a thorny issue for survivors of acute myocardial infarction (AMI), due to the regenerative inertia of myocardial cells. Cell-free therapies, such as exosome transplantation, have become a potential strategy for myocardial injury. The aim of this study was to investigate the role of engineered exosomes in overexpressing Growth Differentiation Factor-15 (GDF-15) (GDF15-EVs) after myocardial injury, and their molecular mechanisms in cardiac repair.

Methods

H9C2 cells were transfected with GDF-15 lentivirus or negative control. The exosomes secreted from H9C2 cells were collected and identified. The cellular apoptosis and autophagy of H2O2-injured H9C2 cells were assessed by Western blotting, TUNEL assay, electron microscopy, CCK-8 and caspase 3/7 assay. A rat model of AMI was constructed by ligating the left anterior descending artery. The anti-apoptotic, pro-angiogenic effects of GDF15-EVs treatment, as well as ensuing functional and histological recovery were evaluated. Then, mRNA sequencing was performed to identify the differentially expressed mRNAs after GDF15-EVs treatment.

Results

GDF15-EVs inhibited apoptosis and promoted autophagy in H2O2 injured H9C2 cells. GDF15-EVs effectively decreased the infarct area and enhanced the cardiac function in rats with AMI. Moreover, GDF15-EVs hindered inflammatory cell infiltration, inhibited cell apoptosis, and promoted cardiac angiogenesis in rats with AMI. RNA sequence showed that telomerase reverse transcriptase (TERT) mRNA was upregulated in GDF15-EVs-treated H9C2 cells. AMPK signaling was activated after GDF15-EVs. Silencing TERT impaired the protective effects of GDF15-EVs on H2O2-injured H9C2 cells.

Conclusion

GDF15-EVs could fulfil their protective effects against myocardial injury by upregulating the expression of TERT and activating the AMPK signaling pathway. GDF15-EVs might be exploited to design new therapies for AMI.

Platelet-derived extracellular vesicles: a new-generation nanostructured tool for chronic wound healing

Chronic nonhealing wounds pose a serious challenge to regaining skin function and integrity. Platelet-derived extracellular vesicles (PEVs) are nanostructured particles with the potential to promote wound healing since they can enhance neovascularization and cell migration and reduce inflammation and scarring. This work provides an innovative overview of the technical laboratory issues in PEV production, PEVs' role in chronic wound healing and the benefits and challenges in its clinical translation. The article also explores the challenges of proper sourcing, extraction techniques and storage conditions, and discusses the necessity of further evaluations and combinational therapeutics, including dressing biomaterials, M2-derived exosomes, mesenchymal stem cells-derived extracellular vesicles and microneedle technology, to boost their therapeutic efficacy as advanced strategies for wound healing.

The bone mesenchymal stem cell-derived exosomal miR-146a-5p promotes diabetic wound healing in mice via macrophage M1/M2 polarization

A diabetic wound is a refractory disease that afflicts patients globally. MicroRNA-146a-5p (miR-146a-5p) is reported to represent a potential therapeutic target for diabetic wounds. However, microRNA easily degrades in the wound microenvironment. This study extracted bone marrow mesenchymal stem cell (BMSC)-derived exosomes (EXO). Electroporation technology was used to load miR-146a-5p into EXO (labeled as EXO-miR-146a). The endothelial cells (human umbilical vein endothelial cells [HUVECs]) and macrophages were cocultured in transwell chambers in the presence of high glucose. Cell proliferation, migration, and angiogenesis were measured with cell counting kit 8, scratch, and tube forming assays, respectively. Flow cytometry was introduced to validate the biomarker of macrophages and BMSCs. The expression level of macrophage polarization-related proteins and tumor necrosis factor receptor-associated factor 6 (TRAF6) was assessed with western blotting analysis. The full-thickness skin wound model was developed to verify the in vitro results. EXO-miR-146a promoted the proliferation, migration, and angiogenesis of HUVECs in the hyperglycemic state by suppressing the TRAF6 expression in vitro. Additionally, EXO-miR-146a treatment facilitated M2 but inhibited M1 macrophage polarization. Furthermore, EXO-miR-146a enhances reepithelialization, angiogenesis, and M2 macrophage polarization, thereby accelerating diabetic wound healing in vivo. The EXO-miR-146a facilitated M2 macrophage polarization, proliferation, migration, and angiogenesis of HUVECs through TRAF6, thereby ameliorating intractable diabetic wound healing. These results established the basis for using EXO to deliver drugs and revealed mediators for diabetic wound treatment.

New Insights into Cardiovascular Diseases Treatment Based on Molecular Targets

Cardiovascular diseases (CVDs) which consist of ischemic heart disease, stroke, heart failure, peripheral arterial disease, and several other cardiac and vascular conditions are one of the most common causes of death worldwide and often co-occur with diabetes mellitus and lipid disorders which worsens the prognosis and becomes a therapeutic challenge. Due to the increasing number of patients with CVDs, we need to search for new risk factors and pathophysiological changes to create new strategies for preventing, diagnosing, and treating not only CVDs but also comorbidities like diabetes mellitus and lipid disorders. As increasing amount of patients suffering from CVDs, there are many therapies which focus on new molecular targets like proprotein convertase subtilisin/kexin type 9 (PCSK9), angiopoietin-like protein 3, ATP-citrate lyase, or new technologies such as siRNA in treatment of dyslipidemia or sodium-glucose co-transporter-2 and glucagon-like peptide-1 in treatment of diabetes mellitus. Both SGLT-2 inhibitors and GLP-1 receptor agonists are used in the treatment of diabetes, however, they proved to have a beneficial effect in CVDs as well. Moreover, a significant amount of evidence has shown that exosomes seem to be associated with myocardial ischaemia and that exosome levels correlate with the severity of myocardial injury. In our work, we would like to focus on the above mechanisms. The knowledge of them allows for the appearance of new strategies of treatment among patients with CVDs.

Challenges and future scope of exosomes in the treatment of cardiovascular diseases

Exosomes are nanosized vesicles that carry biologically diverse molecules for intercellular communication. Researchers have been trying to engineer exosomes for therapeutic purposes by using different approaches to deliver biologically active molecules to the various target cells efficiently. Recent technological advances may allow the biodistribution and pharmacokinetics of exosomes to be modified to meet scientific needs with respect to specific diseases. However, it is essential to determine an exosome's optimal dosage and potential side effects before its clinical use. Significant breakthroughs have been made in recent decades concerning exosome labelling and imaging techniques. These tools provide in situ monitoring of exosome biodistribution and pharmacokinetics and pinpoint targetability. However, because exosomes are nanometres in size and vary significantly in contents, a deeper understanding is required to ensure accurate monitoring before they can be applied in clinical settings. Different research groups have established different approaches to elucidate the roles of exosomes and visualize their spatial properties. This review covers current and emerging strategies for in vivo and in vitro exosome imaging and tracking for potential studies.

Unraveling the Intricate Roles of Exosomes in Cardiovascular Diseases: A Comprehensive Review of Physiological Significance and Pathological Implications

Exosomes, as potent intercellular communication tools, have garnered significant attention due to their unique cargo-carrying capabilities, which enable them to influence diverse physiological and pathological functions. Extensive research has illuminated the biogenesis, secretion, and functions of exosomes. These vesicles are secreted by cells in different states, exerting either protective or harmful biological functions. Emerging evidence highlights their role in cardiovascular disease (CVD) by mediating comprehensive interactions among diverse cell types. This review delves into the significant impacts of exosomes on CVD under stress and disease conditions, including coronary artery disease (CAD), myocardial infarction, heart failure, and other cardiomyopathies. Focusing on the cellular signaling and mechanisms, we explore how exosomes mediate multifaceted interactions, particularly contributing to endothelial dysfunction, oxidative stress, and apoptosis in CVD pathogenesis. Additionally, exosomes show great promise as biomarkers, reflecting differential expressions of NcRNAs (miRNAs, lncRNAs, and circRNAs), and as therapeutic carriers for targeted CVD treatment. However, the specific regulatory mechanisms governing exosomes in CVD remain incomplete, necessitating further exploration of their characteristics and roles in various CVD-related contexts. This comprehensive review aims to provide novel insights into the biological implications of exosomes in CVD and offer innovative perspectives on the diagnosis and treatment of CVD.

Engineered Vesicles and Hydrogel Technologies for Myocardial Regeneration

Increased prevalence of cardiovascular disease and potentially life-threatening complications of myocardial infarction (MI) has led to emerging therapeutic approaches focusing on myocardial regeneration and restoration of physiologic function following infarction. Extracellular vesicle (EV) technology has gained attention owing to the biological potential to modulate cellular immune responses and promote the repair of damaged tissue. Also, EVs are involved in local and distant cellular communication following damage and play an important role in initiating the repair process. Vesicles derived from stem cells and cardiomyocytes (CM) are of particular interest due to their ability to promote cell growth, proliferation, and angiogenesis following MI. Although a promising candidate for myocardial repair, EV technology is limited by the short retention time of vesicles and rapid elimination by the body. There have been several successful attempts to address this shortcoming, which includes hydrogel technology for the sustained bioavailability of EVs. This review discusses and summarizes current understanding regarding EV technology in the context of myocardial repair.

Potential Therapeutic Effects of Human Amniotic Epithelial Cells on Gynecological Disorders Leading to Infertility or Abortion

The induction of feto-maternal tolerance, fetal non-immunogenicity, and the regulation of mother's immune system are essential variables in a successful pregnancy. Fetal membranes have been used as a source of stem cells and biological components in recent decades. Human amniotic epithelial cells (hAEC) have stem/progenitor characteristics like those found in the amniotic membrane. Based on their immunomodulatory capabilities, recent studies have focused on the experimental and therapeutic applications of hAECs in allograft transplantation, autoimmune disorders, and gynecological problems such as recurrent spontaneous abortion (RSA), recurrent implantation failure (RIF), and premature ovarian failure (POF). This review discusses some of the immunomodulatory features and therapeutic potential of hAECs in preventing infertility, miscarriage, and implantation failure by controlling the maternal immune system.

Extracellular Vesicles and Pathological Cardiac Hypertrophy

Pathological cardiac hypertrophy is a well-recognized risk factor for cardiovascular diseases (CVDs). Although lots of efforts have been made to illustrate the underlying molecular mechanisms, many issues remain undiscovered. Recently, intercellular communication by delivering small molecules between different cell types in the progression of cardiac hypertrophy has been reported, including bioactive nucleic acids or proteins. These extracellular vesicles (EVs) may act in an autocrine or paracrine manner between cardiomyocytes and noncardiomyocytes to provoke or inhibit cardiac remodeling and hypertrophy. Besides, EVs can be used as novel diagnostic or prognostic biomarkers in cardiac hypertrophy and also may serve as potential therapeutic targets due to its biocompatible nature and low immunogenicity. In this chapter, we will first summarize the current knowledge about EVs from different cells in pathological cardiac hypertrophy. Then, we will focus on the value of EVs as therapeutic agents and biomarkers for pathological myocardial hypertrophy.

Injection-Free Delivery of MSC-Derived Extracellular Vesicles for Myocardial Infarction Therapeutics

As emerging therapeutic factors, extracellular vesicles (EVs) offer significant potential for myocardial infarction (MI) treatment. Current delivery approaches for EVs involve either intra-myocardial or intravenous injection, where both have inherent limitations for downstream clinical applications such as secondary tissue injury and low delivery efficiency. Herein, an injection-free approach for delivering EVs onto the heart surface to treat MI is proposed. By spraying a mixture of EVs, gelatin methacryloyl (GelMA) precursors, and photoinitiators followed by visible light irradiation for 30 s, EVs are physically entrapped within the GelMA hydrogel network covering the surface of the heart, resulting in an enhanced retention rate. Moreover, EVs are gradually released from the hydrogel network through a combination of diffusion and/or enzymatic degradation of the hydrogel, and they are effectively taken up by the sprayed tissue area. More importantly, the released EVs further migrate deep into myocardium tissue, which exerts an improved therapeutic effect. In an MI-induced mice model, the group treated with EVs-laden GelMA hydrogels shows significant recovery in cardiac function after 4 weeks. The work demonstrates a new strategy for delivering EVs into cardiac tissues for MI treatment in a localized manner with high retention.

Exosomal miR-455-3p from BMMSCs prevents cardiac ischemia-reperfusion injury

OBJECTIVE

Bone marrow mesenchymal stem cells (BMMSCs) exert protective effects against myocardial infarction (MI). Here, we focused on the function and mechanism of miR-455-3p from BMMSCs-derived exosomes (BMMSCs-Exo) in myocardial infarction.

MATERIALS AND METHODS

BMMSCs were isolated from rat bone marrow, and the exosomes from the culture medium of BMMSCs were separated, and administered to H9C2 cells under hypoxia-reperfusion (H/R) stimulation. MTT and TUNEL staining analyzed cell viability and apoptosis, respectively. RT-qPCR determined miR-455-3p expression. Apoptosis-related proteins, autophagy-associated proteins, and the MEKK1-MKK4-JNK signaling pathway were detected. The interaction between miR-455-3p and MEKK1 was confirmed through dual luciferase activity and RIP assay. An in vivo ischemia reperfusion (I/R) model was established in rats. 2, 3, 5 triphenyltetrazolium chloride (TTC) staining, hematoxylin-eosin (H&E) staining, Masson staining, and TUNEL staining evaluated the infarct volume and histopathological changes.

RESULTS

miR-455-3p's expression was down-regulated in BMMSCs-derived exosomes, I/R myocardial tissues, and H/R myocardial cells. miR-455-3p enriched by BMMSC exosomes reduced H/R-mediated cardiomyocyte damage and death-related autophagy. miR-455-3p upregulation suppressed MEKK1-MKK4-JNK. MEKK1 overexpression notably mitigated cell apoptosis, cramped cell viability, suppressed autophagy expansion, and attenuated Exo-miR-455-3p's protection on H/R myocardial cells. In-vivo trials reflected that BMMSC exosomes enriched with miR-455-3p repressed ischemia reperfusion-induced myocardial damage and myocardial cell function.

CONCLUSION

miR-455-3p, shuttled by exosomes from MSCs, targets the MEKK1-MKK4-JNK signaling pathway to guard against myocardial ischemia-reperfusion damage.

Cardiac Remodeling and Repair: Recent Approaches, Advancements, and Future Perspective

The limited ability of mammalian adult cardiomyocytes to proliferate following an injury to the heart, such as myocardial infarction, is a major factor that results in adverse fibrotic and myocardial remodeling that ultimately leads to heart failure. The continued high degree of heart failure-associated morbidity and lethality requires the special attention of researchers worldwide to develop efficient therapeutics for cardiac repair. Recently, various strategies and approaches have been developed and tested to extrinsically induce regeneration and restoration of the myocardium after cardiac injury have yielded encouraging results. Nevertheless, these interventions still lack adequate success to be used for clinical interventions. This review highlights and discusses both cell-based and cell-free therapeutic approaches as well as current advancements, major limitations, and future perspectives towards developing an efficient therapeutic method for cardiac repair.

Mechanism of exosomal miR-155 derived from bone marrow mesenchymal stem cells on stemness maintenance and drug resistance in myeloma cells

Objective

This study was to explore the effect of exosomal miR-155 derived from bone marrow mesenchymal stem cells (BMSCs) on stemness maintenance and drug resistance in MPC-11 multiple myeloma cells.

Methods

MPC-11 cells were transfected with mimics or inhibitors of miR-155. miR-155 expression was detected by qRT-PCR, cell condition was observed, and the expression of stemness maintenance markers OCT-4 and Nanog was observed by immunofluorescence. The expression of proteins associated with the Hedgehog signaling pathway and drug resistance was evaluated by western blot. To investigate whether exosomes affect cell behavior by horizontal delivery of miR-155, MPC-11 cells were co-cultured with exosomes isolated from BMSCs that were transfected with mimics or inhibitors of miR-155. Cell proliferation and the expression of proteins related to stemness maintenance protein and drug resistance were examined.

Results

In function assays, after miR-155-mimics transfection, the expression levels of proteins related to stemness maintenance marker, Hedgehog signaling, and drug resistance were increased in MPC-11 cells. BMSC-derived exosomes carrying miR-155 inhibited apoptosis, promoted cell division, and upregulated the expression of protein associated with stemness maintenance, Hedgehog signaling, and drug resistance.

Conclusion

Therefore, our findings indicate that exosomal delivery of miR-155 exerted the same effect as transfection did on the stemness maintenance and drug resistance of multiple myeloma cells.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13018-021-02793-9.

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.

Cardiac fibrosis: Myofibroblast-mediated pathological regulation and drug delivery strategies

Cardiac fibrosis remains an unresolved problem in heart diseases. After initial injury, cardiac fibroblasts (CFs) are activated and subsequently differentiate into myofibroblasts (myoFbs) that are major mediator cells in the pathological remodeling. MyoFbs exhibit proliferative and secretive characteristics, and contribute to extracellular matrix (ECM) turnover, collagen deposition. The persistent functions of myoFbs lead to fibrotic scars and cardiac dysfunction. The anti-fibrotic treatment is hindered by the elusive mechanism of fibrosis and lack of specific targets on myoFbs. In this review, we will outline the progress of cardiac fibrosis and its contributions to the heart failure. We will also shed light on the role of myoFbs in the regulation of adverse remodeling. The communication between myoFbs and other cells that are involved in the heart injury and repair respectively will be reviewed in detail. Then, recently developed therapeutic strategies to treat fibrosis will be summarized such as i) chimeric antigen receptor T cell (CAR-T) therapy with an optimal target on myoFbs, ii) direct reprogramming from stem cells to quiescent CFs, iii) "off-target" small molecular drugs. The application of nano/micro technology will be discussed as well, which is involved in the construction of cell-based biomimic platforms and "pleiotropic" drug delivery systems.

Dystrophin Deficiency Causes Progressive Depletion of Cardiovascular Progenitor Cells in the Heart

Duchenne muscular dystrophy (DMD) is a devastating condition shortening the lifespan of young men. DMD patients suffer from age-related dilated cardiomyopathy (DCM) that leads to heart failure. Several molecular mechanisms leading to cardiomyocyte death in DMD have been described. However, the pathological progression of DMD-associated DCM remains unclear. In skeletal muscle, a dramatic decrease in stem cells, so-called satellite cells, has been shown in DMD patients. Whether similar dysfunction occurs with cardiac muscle cardiovascular progenitor cells (CVPCs) in DMD remains to be explored. We hypothesized that the number of CVPCs decreases in the dystrophin-deficient heart with age and disease state, contributing to DCM progression. We used the dystrophin-deficient mouse model (mdx) to investigate age-dependent CVPC properties. Using quantitative PCR, flow cytometry, speckle tracking echocardiography, and immunofluorescence, we revealed that young mdx mice exhibit elevated CVPCs. We observed a rapid age-related CVPC depletion, coinciding with the progressive onset of cardiac dysfunction. Moreover, mdx CVPCs displayed increased DNA damage, suggesting impaired cardiac muscle homeostasis. Overall, our results identify the early recruitment of CVPCs in dystrophic hearts and their fast depletion with ageing. This latter depletion may participate in the fibrosis development and the acceleration onset of the cardiomyopathy.

Exosomes derived from human amniotic fluid mesenchymal stem cells alleviate cardiac fibrosis via enhancing angiogenesis in vivo and in vitro

Background

Cardiac fibrosis is a pathological process characterized by excess extracellular matrix (ECM) deposition and plays a critical role in nearly all types of heart disease. The mechanism of cardiac fibrosis is still unclear and no effective medication treatment of cardiac fibrosis. Research showed that mesenchymal stem cell (MSC) derived exosomes may play a critical role in cardiac fibrosis. The effect of human amniotic fluid MSC (hAFMSC)-derived exosomes (hAFMSCExos) on cardiac fibrosis has remained unclear.

Methods

The hAFMSCExos were extracted using a sequential centrifugation approach. The effects of hAFMSCExos on angiogenesis were analyzed both in human umbilical vein endothelial cells (HUVECs) after oxygen and glucose deprivation (OGD) in vitro, and in isoproterenol (ISO) induced-cardiac fibrosis in vivo.

Results

The hAFMSCExos remarkably up-regulate the motility and migration of HUVECs after OGD compared with phosphate-buffered saline (PBS). Meanwhile, total tube length, total branching points and total loops were significantly raised in HUVECs after OGD treated with hAFMSCExos. The hAFMSCExos alleviated the cardiac fibrosis degree tested by hematoxylin-eosin (H&E) and Masson staining. The protein levels of Collagen I and α-smooth muscle actin (α-SMA) were lower in exosomes group rats than PBS group. Immunofluorescence suggested that hAFMSCExos can promote the expression of CD31 in the rats. Meanwhile, the number of regenerated microvessels was significantly enhanced in rats administrated with exosomes by quantitative analysis of microvessel density. Furthermore, the micro-CT scanning evidenced that hAFMSCExos promote angiogenesis after cardiac fibrosis. The levels of hypoxia-inducible factor 1 α (HIF-1α) and vascular endothelial growth factor (VEGF) expression in the left ventricle accepted HUVECs were higher than PBS treatment at 7 days post-treatment by Western blot analysis.

Conclusions

The hAFMSCExos have proangiogenic effects on endothelial cells and enhanced angiogenesis in cardiac fibrosis. The hAFMSCExos may be a promising potential treatment strategy for cardiac fibrosis.

Macrophage migration inhibitory factor facilitates the therapeutic efficacy of mesenchymal stem cells derived exosomes in acute myocardial infarction through upregulating miR-133a-3p

Background

Exosome transplantation is a promising cell-free therapeutic approach for the treatment of ischemic heart disease. The purpose of this study was to explore whether exosomes derived from Macrophage migration inhibitory factor (MIF) engineered umbilical cord MSCs (ucMSCs) exhibit superior cardioprotective effects in a rat model of AMI and reveal the mechanisms underlying it.

Results

Exosomes isolated from ucMSCs (MSC-Exo), MIF engineered ucMSCs (MIF-Exo) and MIF downregulated ucMSCs (siMIF-Exo) were used to investigate cellular protective function in human umbilical vein endothelial cells (HUVECs) and H9C2 cardiomyocytes under hypoxia and serum deprivation (H/SD) and infarcted hearts in rats. Compared with MSC-Exo and siMIF-Exo, MIF-Exo significantly enhanced proliferation, migration, and angiogenesis of HUVECs and inhibited H9C2 cardiomyocyte apoptosis under H/SD in vitro. MIF-Exo also significantly inhibited cardiomyocyte apoptosis, reduced fibrotic area, and improved cardiac function as measured by echocardiography in infarcted rats in vivo. Exosomal miRNAs sequencing and qRT-PCR confirmed miRNA-133a-3p significantly increased in MIF-Exo. The biological effects of HUVECs and H9C2 cardiomyocytes were attenuated with incubation of MIF-Exo and miR-133a-3p inhibitors. These effects were accentuated with incubation of siMIF-Exo and miR-133a-3p mimics that increased the phosphorylation of AKT protein in these cells.

Conclusion

MIF-Exo can provide cardioprotective effects by promoting angiogenesis, inhibiting apoptosis, reducing fibrosis, and preserving heart function in vitro and in vivo. The mechanism in the biological activities of MIF-Exo involves miR-133a-3p and the downstream AKT signaling pathway.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-021-00808-5.

Application of Cell, Tissue, and Biomaterial Delivery in Cardiac Regenerative Therapy

Cardiovascular diseases (CVD) are the leading cause of death around the world, being responsible for 31.8% of all deaths in 2017 (Roth, G. A. et al. The Lancet 2018, 392, 1736-1788). The leading cause of CVD is ischemic heart disease (IHD), which caused 8.1 million deaths in 2013 (Benjamin, E. J. et al. Circulation 2017, 135, e146-e603). IHD occurs when coronary arteries in the heart are narrowed or blocked, preventing the flow of oxygen and blood into the cardiac muscle, which could provoke acute myocardial infarction (AMI) and ultimately lead to heart failure and death. Cardiac regenerative therapy aims to repair and refunctionalize damaged heart tissue through the application of (1) intramyocardial cell delivery, (2) epicardial cardiac patch, and (3) acellular biomaterials. In this review, we aim to examine these current approaches and challenges in the cardiac regenerative therapy field.

Bone marrow mesenchymal stem cell-derived exosomes attenuate cardiac hypertrophy and fibrosis in pressure overload induced remodeling

The multiple therapeutic effects of bone marrow mesenchymal stem cells (BM-MSCs) have been verified in ischemic and reperfusion diseases. Exosomes are thought to play vital roles in MSCs-related cardioprotective effects. Recently, more and more evidences indicated that apoptosis and fibrosis were crucial pathological mechanisms in cardiac remodeling. Whether MSCs-derived exosomes could regulate cardiac hypertrophy and remodeling need to be explored. Murine BM-MSCs-derived exosomes were isolated by differential gradient centrifugation method. The transverse aortic constriction (TAC) mice model was established to promote cardiac remodeling. Cardiac function and remodeling were assessed via echocardiography and histology analysis. Myocytes apoptosis was determined by TUNEL fluorescence staining. Meanwhile, premature senescence was detected by β-galactosidase (SA-β-gal) staining. Related proteins and mRNA alternation were assessed via western blotting and quantitative reverse transcription polymerase chain reaction, respectively. MSCs-derived exosomes significantly protected myocardium against cardiac hypertrophy, attenuated myocardial apoptosis, and fibrosis and preserved heart function when pressure overload. In cultured myocytes, MSCs-derived exosomes also prevented cell hypertrophy stimulated with angiotensin II. One the other hand, exosomes promoted premature senescence of myofibroblasts vitro, indicating its anti-fibrosis effect in cardiac remodeling. Exosomes protected cardiomyocytes against pathological hypertrophy. It may provide a promising future treatment for heart failure.

Exosomes derived from human umbilical cord MSCs rejuvenate aged MSCs and enhance their functions for myocardial repair

Background

Age and other cardiovascular risk factors have been reported to impair the activities of mesenchymal stem cells (MSCs), which will affect the efficacy of stem cell transplantation. The objective of the study is to investigate whether exosomes derived from human umbilical cord MSCs (UMSCs) could enhance the activities of bone marrow MSCs from old person (OMSCs), and improve their capacity for cardiac repair.

Methods

Exosomes extracted from conditioned medium of UMSCs were used to treat OMSCs to generate OMSCs^Exo. The key molecule in the exosomes that have potential to rejuvenate aged MSCs were screened, and the role of OMSC was tested in the mouse model of mycardial infarction (MI).

Results

We found the activity of senescence-associated β-galactosidase and the expression of aging-related factors such as p53, p21, and p16 were significantly higher in OMSCs than those in UMSCs. After treatment with UMSC exosomes, these senescence phenotypes of OMSCs were remarkably reduced. The proliferation, migration, differentiation, and anti-apoptotic and paracrine effect were increased in OMSCs^Exo. In vivo study, mice with cardiac infarction had significantly better cardiac function, less fibrosis, and more angiogenesis after they were injected with OMSCs^Exo as compared with those with OMSC. There was more miR-136 expression in UMSCs and OMSCs^Exo than in OMSCs. Upregulation of miR-136 by transfection of miR-136 mimic into OMSCs significantly attenuated the apoptosis and senescence of OMSCs. Apoptotic peptidase activating factor (Apaf1) was found to be the downstream gene that is negatively regulated by miR-136 via directly targeting at its 3′UTR.

Conclusion

Our data suggest that exosomes from young MSCs can improve activities of aged MSCs and enhance their function for myocardial repair by transferring exosomal miR-136 and downregulating Apaf1.

[Photoreceptor cell transplantation for future treatment of retinitis pigmentosa]

In inherited retinal diseases such retinitis pigmentosa, characterized by progressive loss of light sensitive neurons (photoreceptors), cell therapy is now considered as an attractive strategy. Photoreceptor cell replacement would be valuable for restoring function to retinas in a way that is independent from the cause of the disease. With advances in stem cell biology, considerable strides have been made towards the generation of retinal cells, in particular with the development of 3D culture systems allowing the generation of retinal organoids from pluripotent stem cells. In this review, we present a state-of-the art of preclinical strategies conducted in animal models for photoreceptor replacement from stem cell-derived photoreceptors and we discuss the important obstacles to overcome in the future.

Cardiovascular morbidities of obstructive sleep apnea and the role of circulating extracellular vesicles

Obstructive sleep apnea (OSA) is characterized by recurrent upper airway collapse during sleep resulting in impaired blood gas exchange, namely intermittent hypoxia (IH) and hypercapnia, fragmented sleep (SF), increased oxidative stress and systemic inflammation. Among a myriad of potential associated morbidities, OSA has been particularly implicated as mechanistically contributing to the prevalence and severity of cardiovascular diseases (CVD). However, the benefits of continuous positive airway pressure (CPAP), which is generally employed in OSA treatment, to either prevent or improve CVD outcomes remain unconvincing, suggesting that the pathophysiological mechanisms underlying the incremental CVD risk associated with OSA are not clearly understood. One of the challenges in development of non-invasive diagnostic assays is the ability to identify clinically and mechanistically relevant biomarkers. Circulating extracellular vesicles (EVs) and their cargos reflect underlying changes in cellular homeostasis and can provide insights into how cells and systems cope with physiological perturbations by virtue of the identity and abundance of miRNAs, mRNAs, proteins, and lipids that are packaged in the EVs under normal as well as diseased states, such as OSA. EVs can not only provide unique insights into coordinated cellular responses at the organ or systemic level, but can also serve as reporters of the effects of OSA in CVD, either by their properties enabling regeneration and repair of injured vascular cells or by damaging them. Here, we highlight recent progress in the pathological CVD consequences of OSA, and explore the putative roles of EVs in OSA-associated CVD, along with emerging diagnostic and therapeutic opportunities.

The reviews of this paper are available via the supplemental material section.

Circulating exosomes derived from transplanted progenitor cells aid the functional recovery of ischemic myocardium

The stem cell field is hindered by its inability to noninvasively monitor transplanted cells within the target organ in a repeatable, time-sensitive, and condition-specific manner. We hypothesized that quantifying and characterizing transplanted cell-derived exosomes in the recipient plasma would enable reliable, noninvasive surveillance of the conditional activity of the transplanted cells. To test this hypothesis, we used a human-into-rat xenogeneic myocardial infarction model comparing two well-studied progenitor cell types: cardiosphere-derived cells (CDCs) and c-kit⁺ cardiac progenitor cells (CPCs), both derived from the right atrial appendage of adults undergoing cardiopulmonary bypass. CPCs outperformed the CDCs in cell-based and in vivo regenerative assays. To noninvasively monitor the activity of transplanted CDCs or CPCs in vivo, we purified progenitor cell-specific exosomes from recipient total plasma exosomes. Seven days after transplantation, the concentration of plasma CPC-specific exosomes increased about twofold compared to CDC-specific exosomes. Computational pathway analysis failed to link CPC or CDC cellular messenger RNA (mRNA) with observed myocardial recovery, although recovery was linked to the microRNA (miRNA) cargo of CPC exosomes purified from recipient plasma. We further identified mechanistic pathways governing specific outcomes related to myocardial recovery associated with transplanted CPCs. Collectively, these findings demonstrate the potential of circulating progenitor cell-specific exosomes as a liquid biopsy that provides a noninvasive window into the conditional state of the transplanted cells. These data implicate the surveillance potential of cell-specific exosomes for allogeneic cell therapies.

Small but significant: Insights and new perspectives of exosomes in cardiovascular disease

Cardiovascular diseases (CVDs) are a major health problem worldwide, and health professionals are still actively seeking new and effective approaches for CVDs treatment. Presently, extracellular vesicles, particularly exosomes, have gained its popularity for CVDs treatment because of their function as messengers for inter- and extra-cellular communications to promote cellular functions in cardiovascular system. However, as a newly developed field, researchers are still trying to fully understand the role of exosomes, and their mechanism in mediating cardiac repair process. Therefore, a comprehensive review of this topic can be timely and favourable. In this review, we summarized the basic biogenesis and characterization of exosomes and then further extended the focus on the circulating exosomes in cellular communication and stem cell-derived exosomes in cardiac disease treatment. In addition, we covered interactions between the heart and other organs through exosomes, leading to the diagnostic characteristics of exosomes in CVDs. Future perspectives and limitations of exosomes in CVDs were also discussed with a special focus on exploring the potential delivery routes, targeting the injured tissue and engineering novel exosomes, as well as its potential as one novel target in the metabolism-related puzzle.

Long-noncoding RNA MALAT1 sponges microRNA-92a-3p to inhibit doxorubicin-induced cardiac senescence by targeting ATG4a

The clinical application of doxorubicin (Dox) is limited due to its undesirable cardiotoxicity side effects. Cellular senescence plays an important role in Dox-induced cardiotoxicity. Exosomes derived from stem cells showed a therapeutic effect in Dox-induced cardiomyopathy (DIC). Hypoxia-preconditioned exosomes (exosome^Hypoxia) display pro-metabolism and pro-survival abilities. Several long-noncoding RNAs/microRNAs act as competing endogenous RNAs (ceRNAs) modulating DIC. No study investigated whether exosome^Hypoxia could attenuate DIC through modulating ceRNAs.Treatment of the human adipose-derived mesenchymal stem cells with hypoxia induced lncRNA-MALAT1 accumulation in the secreted exosomes. In addition, the lncRNA-MALAT1 was identified as an exosomal transfer RNA to repress miR-92a-3p expression. Silencing the lncRNA-MALAT1 in MSCs or miR-92a-3p overexpression in cardiomyocytes significantly impaired the rejuvenation induced by exosome^Hypoxia. TargetScan and luciferase assay showed that miR-92a-3p targeted the ATG4a 3' untranslated region. Silencing ATG4a blocked the anti-senescent effect of exosome^Hypoxia.This study identified the lncRNA-MALAT1 that functioned as ceRNA binding to miR-92a-3p, leading to ATG4a activation, thus improving mitochondrial metabolism. LncRNA-MALAT1/miR-92a-3p/ATG4a partially mediates the cardioprotective roles of exosome^Hypoxia in Dox-induced cardiac damage. Exosome^Hypoxia may serve as a potential therapeutic target against DIC.

Exosomes: Cell-Free Therapy for Cardiovascular Diseases

Cardiovascular diseases (CVDs) are an important cause of death and disease worldwide. Because injured cardiac tissue cannot be repaired itself, it is urgent to develop other alternate therapies. Stem cells can be differentiated into cardiomyocytes, endothelial cells, and vascular smooth muscle cells for the treatment of CVDs. Therefore, cell therapy has recently been considered a viable treatment option that can significantly improve cardiac function. Nonetheless, implanted stem cells rarely survive in the recipient heart, suggesting that the benefits of stem cell therapy may involve other mechanisms. Exosomes derived from stem cells have a myocardial protection function after myocardial injury, and may be a promising and effective therapy for CVDs. Here, we discuss the application and mechanism of exosomes derived from stem cells in the diagnosis and treatment of CVDs and provide evidence for the application of exosomes in CVDs. Graphical Abstract.

How to Stimulate Myocardial Regeneration in Adult Mammalian Heart: Existing Views and New Approaches

Stem cell-based therapy has been considered as a promising option in the treatment of ischemic heart disease. Although stem cell administration resulted in the temporary improvement of myocardial contractility in the majority of studies, the formation of new cardiomyocytes within the injured myocardium has not been conclusively demonstrated. Consequently, the focus of research in the field has since shifted to stem cell-derived paracrine factors, including cytokines, growth factors, mRNA, and miRNA. Notably, both mRNA and miRNA can enter into the extracellular space either in soluble form or packed into membrane vesicles. Stem cell-derived paracrine factors have been shown to suppress inflammation and apoptosis, stimulate angiogenesis, and amplify the proliferation and differentiation of resident cardiac stem cells (CSCs). Such features have led to exosomes being considered as potential drug candidates affording myocardial regeneration. The search for chemical signals capable of stimulating cardiomyogenesis is ongoing despite continuous debates regarding the ability of mature cardiomyocytes to divide or dedifferentiate, transdifferentiation of other cells into cardiomyocytes, and the ability of CSCs to differentiate into cardiomyocytes. Future research is aimed at identifying novel cell candidates capable of differentiating into cardiomyocytes. The observation that CSCs can undergo intracellular development with the formation of “cell-in-cell structure” and subsequent release of transitory amplifying cells with the capacity to differentiate into cardiomyocytes may provide clues for stimulating regenerative cardiomyogenesis.

Knockout of beta-2 microglobulin enhances cardiac repair by modulating exosome imprinting and inhibiting stem cell-induced immune rejection

BACKGROUND AND AIMS

Allogeneic human umbilical mesenchymal stem cells (alloUMSC) are convenient cell source for stem cell-based therapy. However, immune rejection is a major obstacle for clinical application of alloUMSC for cardiac repair after myocardial infarction (MI). The immune rejection is due to the presence of human leukocyte antigen (HLA) class I molecule which is increased during MI. The aim of this study was to knockout HLA light chain β2-microglobulin (B2M) in UMSC to enhance stem cell engraftment and survival after transplantation.

METHODS AND RESULTS

We developed an innovative strategy using CRISPR/Cas9 to generate UMSC with B2M deletion (B2M-UMSC). AlloUMSC injection induced CD8+ T cell-mediated immune rejection in immune competent rats, whereas no CD8+ T cell-mediated killing against B2M-UMSC was observed even when the cells were treated with IFN-γ. Moreover, we demonstrate that UMSC-derived exosomes can inhibit cardiac fibrosis and restore cardiac function, and exosomes derived from B2M-UMSC are more efficient than those derived from UMSC, indicating that the beneficial effect of exosomes can be enhanced by modulating exosome's imprinting. Mechanistically, microRNA sequencing identifies miR-24 as a major component of the exosomes from B2M-UMSCs. Bioinformatics analysis identifies Bim as a putative target of miR-24. Loss-of-function studies at the cellular level and gain-of-function approaches in exosomes show that the beneficial effects of B2M-UMSCs are mediated by the exosome/miR-24/Bim pathway.

CONCLUSION

Our findings demonstrate that modulation of exosome's imprinting via B2M knockout is an efficient strategy to prevent the immune rejection of alloUMSCs. This study paved the way to the development of new strategies for tissue repair and regeneration without the need for HLA matching.

Utilization of Human Induced Pluripotent Stem Cells for Cardiac Repair

The paracrine effect, mediated by chemical signals that induce a physiological response on neighboring cells in the same tissue, is an important regenerative mechanism for stem cell-based therapy. Exosomes are cell-secreted nanovesicles (50–120 nm) of endosomal origin, and have been demonstrated to be a major contributor to the observed stem cell-mediated paracrine effect in the cardiac repair process. Following cardiac injury, exosomes deriving from exogenous stem cells have been shown to regulate cell apoptosis, proliferation, angiogenesis, and fibrosis in the infarcted heart. Exosomes also play a crucial role in the intercellular communication between donor and recipient cells. Human induced pluripotent stem cells (hiPSCs) are promising cell sources for autologous cell therapy in regenerative medicine. Here, we review recent advances in the field of progenitor-cell derived, exosome-based cardiac repair, with special emphasis on exosomes derived from hiPSCs.

miR-644-5p carried by bone mesenchymal stem cell-derived exosomes targets regulation of p53 to inhibit ovarian granulosa cell apoptosis

Background

This article aims to reveal the therapeutic effects and potential mechanisms of bone mesenchymal stem cell (BMSC)-derived exosomes on premature ovarian failure (POF).

Methods

Exosomes were collected from BMSCs and were used to treat cisplatin-induced POF mouse models. Pathological changes of ovarian tissue were detected by using HE staining and by Western blot that detected the expression of apoptosis-related proteins. In cisplatin-induced primary granulosa cell injury, exosomes were co-cultured with the granulosa cells. The apoptosis or viability of granulosa cells was analyzed by flow cytometry or MTT, respectively. In Target scan and microT-CDS databases, an intersection of miRNAs targeting to p53 was found. The expressions of miRNAs in BMSC-derived exosomes were detected by qRT-PCR. Besides, miR-664-5p targeted to p53 of cells was verified by dual-luciferase reporter assay.

Results

BMSC-derived exosomes improved the follicular morphology of POF mice and inhibited the expression of apoptosis-related protein. By co-culture of exosomes and primary granulosa cells, BMSC-derived exosomes repressed cisplatin-induced granulosa cells apoptosis and increased cells viability, while these effects were abrogated after the exosome-containing RNA was degraded by RNase. By Target scan, microT-CDS and qRT-PCR, miR-664-5p was regarded as the dominated RNA in BMSC-derived exosomes. By dual-luciferase reporter assay, miR-664-5p negatively regulated p53 luciferase activity. After shRNA interfering miR-664-5p of BMSC, BMSC-derived exosomes exerted no protective effect on cisplatin-induced granulosa cell apoptosis.

Conclusion

Our results indicated that miR-644-5p carried by BMSC-derived exosomes inhibited the apoptosis of ovarian granulosa cell by targeting p53 of cells, suggesting that miR-644-5p had the potential to treat POF and restore ovarian function.

Knockout of beta-2 microglobulin reduces stem cell-induced immune rejection and enhances ischaemic hindlimb repair via exosome/miR-24/Bim pathway

Generating universal human umbilical mesenchymal stem cells (UMSCs) without immune rejection is desirable for clinical application. Here we developed an innovative strategy using CRISPR/Cas9 to generate B2M^‐UMSCs in which human leucocyte antigen (HLA) light chain β2‐microglobulin (B2M) was deleted. The therapeutic potential of B2M^‐UMSCs was examined in a mouse ischaemic hindlimb model. We show that B2M^‐UMSCs facilitated perfusion recovery and enhanced running capability, without inducing immune rejection. The beneficial effect was mediated by exosomes. Mechanistically, microRNA (miR) sequencing identified miR‐24 as a major component of the exosomes originating from B2M^‐UMSCs. We identified Bim as a potential target of miR‐24 through bioinformatics analysis, which was further confirmed by loss‐of‐function and gain‐of‐function approaches. Taken together, our data revealed that knockout of B2M is a convenient and efficient strategy to prevent UMSCs‐induced immune rejection, and it provides a universal clinical‐scale cell source for tissue repair and regeneration without the need for HLA matching in the future.

Microvesicles Derived from Human Embryonic Neural Stem Cells Inhibit the Apoptosis of HL-1 Cardiomyocytes by Promoting Autophagy and Regulating AKT and mTOR via Transporting HSP-70

Myocardial reperfusion injury (MRI) induced by cardiomyocyte apoptosis plays an important role in the pathogenesis of a variety of cardiovascular diseases. New MRI treatments involving stem cells are currently being developed because these cells may exert their therapeutic effects primarily through paracrine mechanisms. Microvesicles (MVs) are small extracellular vesicles that have become the key mediators of intercellular communication. MVs derived from stem cells have been reported to play an important role in MRI. In this article, we attempted to explore the mechanisms by which MVs derived from human embryonic neural stem cells (hESC-NSC-derived MVs) rescue MRI. hESCs were differentiated into NSCs, and MVs were isolated from their supernatants by ultracentrifugation. H₂O₂ was used to induce apoptosis in HL-1 cardiomyocytes. Cell viability was detected by using the CCK-8 assay, apoptosis was detected by Annexin V-FITC/PI staining, and apoptosis-related proteins and signalling pathway-related proteins were detected by western blot analysis. Autophagic flux was measured using the tandem fluorescent mRFG-GFP-LC3 assay. Transmission electron microscopy and western blot analysis were adopted to evaluate autophagy levels. hESC-NSC-derived MVs increased the autophagy and inhibited the apoptosis of HL-1 cells exposed to H₂O₂ for 3 h in a dose-dependent manner. Additionally, hESC-NSC-derived MVs contained high levels of heat shock protein 70 (HSP-70), which can increase the level of HSP-70 in cells. Moreover, the same effect could be achieved by heat shock preconditioning of HL-1 cells overexpressing HSP-70. The benefits of NSC-MVs may be due to the involvement of AKT and mTOR signalling pathways. Importantly, hESC-NSC-derived MVs stimulated the activation of the AKTand mTOR signalling pathway in those cells by transporting HSP-70. Our results suggest that hESC-NSC-derived MVs inhibit the apoptosis of HL-1 cardiomyocytes by promoting autophagy and regulating AKT and mTOR via transporting HSP-70. However, this hypothesis requires in vivo confirmation.

Exosome Treatment Enhances Anti-Inflammatory M2 Macrophages and Reduces Inflammation-Induced Pyroptosis in Doxorubicin-Induced Cardiomyopathy

Doxorubicin (Dox) is an effective antineoplastic agent used to treat cancers, but its use is limited as Dox induces adverse cardiotoxic effects. Dox-induced cardiotoxicity (DIC) can lead to heart failure and death. There is no study that investigates whether embryonic stem cell-derived exosomes (ES-Exos) in DIC can attenuate inflammation-induced pyroptosis, pro-inflammatory M1 macrophages, inflammatory cell signaling, and adverse cardiac remodeling. For this purpose, we transplanted ES-Exos and compared with ES-cells (ESCs) to examine pyroptosis, inflammation, cell signaling, adverse cardiac remodeling, and their influence on DIC induced cardiac dysfunction. Therefore, we used C57BL/6J mice ages 10 ± 2 weeks and divided them into four groups (n = 6–8/group): Control, Dox, Dox + ESCs, and Dox + ES-Exos. Our data shows that the Dox treatment significantly increased expression of inflammasome markers (TLR4 and NLRP3), pyroptotic markers (caspase-1, IL1-β, and IL-18), cell signaling proteins (MyD88, p-P38, and p-JNK), pro-inflammatory M1 macrophages, and TNF-α cytokine. This increased pyroptosis, inflammation, and cell signaling proteins were inhibited with ES-Exos or ESCs. Moreover, ES-Exos or ESCs increased M2 macrophages and anti-inflammatory cytokine, IL-10. Additionally, ES-Exos or ESCs treatment inhibited significantly cytoplasmic vacuolization, myofibril loss, hypertrophy, and improved heart function. In conclusion, for the first time we demonstrated that Dox-induced pyroptosis and cardiac remodeling are ameliorated by ES-Exos or ESCs.

Bone marrow mesenchymal stem cell-derived exosomes protect against myocardial infarction by promoting autophagy

Exosomes have been demonstrated to be effective in the treatment of a variety of cardiac disorders. However, the effects of mesenchymal stem cell (MSC) exosomes on myocardial infarction is yet to be determined. The current study aimed to investigate the potential therapeutic effects of MSC exosomes on myocardial injuries that are caused by myocardial infarction. MSCs were isolated from rat bone marrow and were used for exosome enrichment using culture medium. Confirmation that MSCs and exosomes had been successfully extracted was performed using flow cytometry, electron microscopy and western blot analysis. A rat myocardial ischemia reperfusion (I/R) model was established by ligation of the left anterior descending coronary artery. Rat myocardial injuries were determined using 2,3,5-triphenyltetrazolium chloride, Masson and TUNEL staining. H9c2 cell proliferation, apoptosis and migration were analyzed using 5-ethynyl-2′-deoxyuridine, Hoechst staining, flow cytometry and Transwell assays. Marker gene expression was evaluated using reverse transcription-quantitative PCR, western blot analysis and immunofluorescence. Rat MSC exosomes were revealed to suppress myocardial injury and the myocardiocyte functions that were induced by I/R. The results also demonstrated decreased apoptotic protease activating factor-1 and increased autophagy-related protein 13 expression. The H9c2 cell proliferation and migration inhibition, as well as cell apoptosis during hypoxia-reoxygenation (H/R), were suppressed by rat MSC exosomes, with an alteration of the expression of apoptotic and autophagic genes also being demonstrated. The application of autophagy inhibitor 3-methyladenine significantly mitigated the effect of exosomes on H9c2 cell proliferation and apoptosis, which were induced by H/R. Rat MSC exosomes inhibited myocardial infarction pathogenesis, possibly by regulating autophagy.

Embryonic stem cell-derived exosomes inhibit doxorubicin-induced TLR4-NLRP3-mediated cell death-pyroptosis

Doxorubicin (Dox)-induced cardiac side effects are regulated through increased oxidative stress and apoptosis. However, it remains unknown whether Dox induces the specific inflammatory-mediated form of cell death called pyroptosis. The current study is undertaken to determine whether Dox induces pyroptosis in an in vitro model and to test the potential of exosomes derived from embryonic stem cells (ES-Exos) in inhibiting pyroptosis. H9c2 cells were exposed to Dox to generate pyroptosis and then subsequently treated with exosomes to investigate the protective effects of ES-Exos. Mouse embryonic fibroblast-exosomes (MEF-Exos) were used as a cell line control. We confirmed pyroptosis by analyzing the presence of Toll-like receptor 4 (TLR4)-pyrin domain containing-3 (NLRP3) inflammasome that initiates pyroptosis, which was further confirmed with pyroptotic markers caspase-1, IL-1β, caspase-11, and gasdermin-D. The presence of inflammation was confirmed for proinflammatory cytokines, TNF-α, and IL-6. Our data show that Dox exposure significantly (P < 0.05) increases expression of TLR4, NLRP3, pyroptotic markers (caspase-1, IL-1β, caspase-11, and gasdermin-D), and proinflammatory cytokines (TNF-α and IL-6) in H9c2 cells. The increased expression of inflammasome, pyroptosis, and inflammation was significantly (P < 0.05) inhibited by ES-Exos. Interestingly, our cell line control, MEF-Exos, did not show any protective effects. Furthermore, our cytokine array data suggest increased anti-inflammatory (IL-4, IL-9, and IL-13) and decreased proinflammatory cytokines (Fas ligand, IL-12, and TNF-α) in ES-Exos, suggesting that anti-inflammatory cytokines might be mediating the protective effects of ES-Exos. In conclusion, our data show that Dox induces pyroptotic cell death in the H9c2 cell culture model and is attenuated via treatment with ES-Exos.NEW & NOTEWORTHY Doxorubicin (Dox)-induced cardiotoxicity is mediated through increased oxidative stress, apoptosis, and necrosis. We report for the first time as per the best of our knowledge that Dox initiates Toll-like receptor 4 and pyrin domain containing-3 inflammasome formation and induces caspase-1-mediated inflammatory pyroptotic cell death in H9c2 cells. Moreover, we establish that inflammation and pyroptosis is inhibited by embryonic stem cell-derived exosomes that could be used as a future therapeutic option to treat Dox-induced cardiotoxicity.

Exosomes of stem cells from human exfoliated deciduous teeth as an anti-inflammatory agent in temporomandibular joint chondrocytes via miR-100-5p/mTOR

Objectives

Temporomandibular joint osteoarthritis (TMJOA) is an inflammatory joint disease. This study investigated whether exosomes (Exos) of stem cells from human exfoliated deciduous teeth (SHEDs) have a therapeutic effect on TMJ inflammation and elucidated the underlying mechanisms.

Materials and methods

SHEDs were verified by flow cytometry. SHED-Exos were identified by western blotting, nanoparticle tracking analysis, and transmission electron microscopy. Western blot and RT-qPCR were performed to verify the anti-inflammatory effects of SHED-Exos. MicroRNA (miRNA) array analysis was conducted to determine the miRNA expression profiles of SHED-Exos, and the key pathways were analyzed. After chondrocytes were treated with an miR-100-5p mimic or rapamycin, relative expression of genes was measured by RT-qPCR and western blotting. A luciferase reporter assay was performed to reveal the molecular role of the exosomal miR-100 target, mTOR.

Results

MiR-100-5p was enriched in the SHED-Exos. Treatment with SHED-Exos suppressed the expression of interleukin-6 (IL-6), IL-8, matrix metalloproteinase 1 (MMP1), MMP3, MMP9, MMP13, and disintegrin and metalloproteinase with thrombospondin motifs 5 (ADAMTS5). Chondrocytes treated with the miR-100 mimic showed lower expression of MMP1, MMP9, MMP13, ADAMTS5, and mTOR. In contrast, miR-100 downregulation upregulated the MMPs and mTOR. Rapamycin treatment upregulated miR-100 and downregulated MMPs and ADAMTS5. Furthermore, the luciferase reporter assay demonstrated that miR-100-5p directly targeted the mTOR 3′ untranslated region and that SHED-Exos miR-100-5p repressed mTOR expression.

Conclusions

This study demonstrated that SHED-Exos suppress inflammation in TMJ chondrocytes and may thus be a novel therapeutic agent for TMJ inflammation.

Endothelial progenitor cell-derived exosomes facilitate vascular endothelial cell repair through shuttling miR-21-5p to modulate Thrombospondin-1 expression

Background: Our previous studies observed that administration of exosomes from endothelial progenitor cells (EPC) facilitated vascular repair in the rat model of balloon injury. However, the molecular events underlying this process remain elusive. Here, we aim to interrogate the key miRNAs within EPC-derived exosomes (EPC-exosomes) responsible for the activation of endothelial cell (EC) repair. Methods: The efficacy of EPC-exosomes in re-endothelialization was examined by Evans Blue dye and histological examination in the rat model of balloon-induced carotid artery injury. The effects of EPC-exosomes on human vascular EC (HUVEC) were also studied by evaluating the effects on growth, migratory and tube formation. To dissect the underlying mechanism, RNA-sequencing assays were performed to determine miRNA abundance in exosomes and mRNA profiles in exosome-treated HUVECs. Meanwhile, in vitro loss of function assays identified an exosomal miRNA and its target gene in EC, which engaged in EPC-exosomes-induced EC repair. Results: Administration of EPC-exosomes potentiated re-endothelialization in the early phase after endothelial damage in the rat carotid artery. The uptake of exogenous EPC-exosomes intensified HUVEC in proliferation rate, migration and tube-forming ability. Integrative analyses of miRNA-mRNA interactions revealed that miR-21-5p was highly enriched in EPC-exosomes and specifically suppressed the expression of an angiogenesis inhibitor Thrombospondin-1 (THBS1) in the recipient EC. The following functional studies demonstrated a fundamental role of miR-21-5p in the pro-angiogenic activities of EPC-exosomes. Conclusions: The present work highlights a critical event for the regulation of EC behavior by EPC-exosomes, which EPC-exosomes may deliver miR-21-5p and inhibit THBS1 expression to promote EC repair.

Circulating exosomal miRNAs in cardiovascular disease pathogenesis: New emerging hopes

Cardiovascular diseases (CVDs) are one of the leading causes of morbidity and mortality. Standard therapies have failed to significantly increase patients' survival. Moreover, the majority of conventional screening procedures are ineffective for the diagnosis of CVDs at early stages. Accumulating evidence suggests that numerous cell types release a class of nano-sized vesicles named exosomes into the extracellular space. Exosomes are widely distributed in various body fluids and contain a number of diverse biomolecules such as proteins, lipids, and both mRNA and noncoding RNAs which reflect host-cell molecular architecture. MicroRNAs (miRNAs), which can be found in exosomes, could be taken up by both neighboring and distal cells. Not only has recent evidence indicated the regulatory role of exosomal miRNAs in the pathogenesis of CVD, but it has also been shown that differential expression of exosomal miRNAs in CVDs has made them promising biomarkers for early detection of CVDs. Owing to these remarkable features, exosomal miRNAs have emerged as hot spots in research. This review summarizes the role of exosomal miRNAs in the pathogenesis of CVDs and discusses their potential application in the clinical setting as both therapeutic and diagnostic tools.

Exosomes from adipose-derived mesenchymal stem cells ameliorate cardiac damage after myocardial infarction by activating S1P/SK1/S1PR1 signaling and promoting macrophage M2 polarization

Exosomes derived from mesenchymal stem cells (MSCs) are known to participate in myocardial repair after myocardial infarction (MI), but the mechanism remains unclear. Here, we isolated exosomes from adipose-derived MSCs (ADSCs) and examined their effect on MI-induced cardiac damage. To examine the underlying mechanism, H9c2 cells, cardiac fibroblasts, and HAPI cells were used to study the effect of ADSC-exosomes on hypoxia-induced H9c2 apoptosis, TGF-β1-induced fibrosis of cardiac fibroblasts, and hypoxia-induced macrophage M1 polarization using qRT-PCR, western blot, ELISA, immunohistochemistry, immunofluorescence and flow cytometry. ADSC-exosome treatment mitigated MI-induced cardiac damage by suppressing cardiac dysfunction, cardiac apoptosis, cardiac fibrosis, and inflammatory responses in vitro and in vivo. In addition, ADSC-exosome treatment promoted macrophage M2 polarization. Further experiments found that S1P/SK1/S1PR1 signaling was involved in the ADSC-exosome-mediated myocardial repair. Silencing of S1PR1 reversed the inhibitory effect of ADSC-exosomes on MI-induced cardiac apoptosis and fibrosis in vitro. ADSC-exosome-induced macrophage M2 polarization was also reversed after downregulation of S1PR1 under hypoxia conditions, which promoted NFκB and TGF-β1 expression, and suppressed the MI-induced cardiac fibrosis and inflammatory response. In sum, these results indicate that ADSC-derived exosomes ameliorate cardiac damage after MI by activating S1P/SK1/S1PR1 signaling and promoting macrophage M2 polarization.

Human Amniotic Epithelial Cell-Derived Exosomes Restore Ovarian Function by Transferring MicroRNAs against Apoptosis

Premature ovarian failure (POF) is one of the most common complications among female patients with tumors treated with chemotherapy and requires advanced treatment strategies. Human amniotic epithelial cell (hAEC)-based therapy mediates tissue regeneration in a variety of diseases, and increasing evidence suggests that the therapeutic efficacy of hAECs mainly depends on paracrine action. This study aimed to identify exosomes derived from hAECs and explored the therapeutic potential in ovaries damaged by chemotherapy and the underlying molecular mechanism. hAEC-derived exosomes exhibited a cup- or sphere-shaped morphology with a mean diameter of 100 nm and were positive for Alix, CD63, and CD9. hAEC exosomes increased the number of follicles and improved ovarian function in POF mice. During the early stage of transplantation, hAEC exosomes significantly inhibited granulosa cell apoptosis, protected the ovarian vasculature from damage, and were involved in maintaining the number of primordial follicles in the injured ovaries. Enriched microRNAs (miRNAs) existed in hAEC exosomes, and target genes were enriched in phosphatidylinositol signaling and apoptosis pathways. Studies in vitro demonstrated that hAEC exosomes inhibited chemotherapy-induced granulosa cell apoptosis via transferring functional miRNAs, such as miR-1246. Our findings demonstrate that hAEC-derived exosomes have the potential to restore ovarian function in chemotherapy-induced POF mice by transferring miRNAs.

Angiogenic growth factors in myocardial infarction: a critical appraisal

In the recent past, substantial advances have been made in the treatment of myocardial infarction (MI). Despite the impact of these positive developments, MI remains to be a leading cause of morbidity as well as mortality. An interesting hypothesis is that the development of new blood vessels (angiogenesis) or the remodeling of preexisting collaterals may form natural bypasses that could compensate for the occlusion of an epicardial coronary artery. A number of angiogenic factors are proven to be elicited during MI. Exogenous supplementation of these growth factors either in the form of recombinant protein or gene would enhance the collateral vessel formation and thereby improve the outcome after MI. The aim of this review is to describe the nature and potentials of different angiogenic factors, their expression, their efficacy in animal studies, and clinical trials pertaining to MI.

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.

Lipid, Protein, and MicroRNA Composition Within Mesenchymal Stem Cell-Derived Exosomes

Mesenchymal stem cells (MSCs) were regarded as one of the most promising type of seed cells in tissue engineering due to its easy accessibility and multipotent feature of being able to differentiate into adipocyte, osteoblast, cardiomyocytes, and neurons. For years, MSCs have been applied in treating cardiovascular disease, reconstructing kidney injury, and remodeling immune system with remarkable achievements. Basic researches revealed that its clinic effects are not only due to their pluripotent ability but also through their paracrine function that they synthesize and secrete a broad spectrum of growth factors and cytokines. Recent studies show that exosomes is the main paracrine executor of MSCs. The lipid bilayer of exosome maintains its stability and integrity and keeps biological potency of biological substance within it. MSC-derived exosomes were shown to be successful in treating many diseases, including tumor and cardiovascular diseases. However, the exact composition of MSC-derived exosomes is not known yet. In this review, we will discuss the lipid, protein, and microRNA contents within MSC-derived exosomes based on current studies to guide further research and clinical applications of MSC-derived exosomes.

Regenerative Therapy for Cardiomyopathies

Despite substantial advances in the development of medical and interventional strategies in ischemic and non-ischemic heart diseases, cardiovascular diseases (CVDs) remain the leading cause of mortality and morbidity worldwide. Stem cell therapy for heart disease has gained traction over the past two decades and is an emerging option for the treatment of myocardial dysfunction. In this review, we summarize the current literature on different types of stem cells and their potential usage in ischemic and non-ischemic heart diseases. We emphasize the clinical utility of stem cells to improve myocardial structural and function, promote microvascular angiogenesis, and diminish scar size and major adverse cardiovascular events. We also discuss the therapeutic potential of microvesicles, such as exosomes, in the treatment of CVDs, which may open novel avenues for further clinical studies.

Serum Exosomes Attenuate H2O2-Induced Apoptosis in Rat H9C2 Cardiomyocytes via ERK1/2

Exosomes are small-sized vesicles that can be released from cells into the serum. Exosomes play important roles in regulating many biological processes including cell proliferation, apoptosis, cell cycle, and metabolism. However, the roles and mechanisms of plasma exosomes in the apoptosis of rat H9C2 cardiomyocytes are largely unknown. In this study, we isolated plasma exosomes as confirmed by the marker protein CD63. Using flow cytometry and western blot analysis, we found that exosomes attenuated hydrogen peroxide (H₂O₂)-induced apoptosis and improved survival of rat H9C2 cardiomyocytes. Furthermore, the anti-apoptosis effects of serum exosomes in rat H9C2 cardiomyocytes were mediated by the activation of ERK1/2 signaling pathway. These data indicated that plasma exosomes had the protective effects against cardiomyocyte apoptosis and might be a novel therapy strategy for myocardial injury.