Exosomes derived from adipose tissue, bone marrow, and umbilical cord blood for cardioprotection after myocardial infarction

Protective effects of umbilical cord mesenchymal stem cell exosomes in a diabetic rat model through live retinal imaging

AIM

To assess the protective effect of human umbilical cord mesenchymal stem cell exosomes (hucMSC-Exs) in a diabetic rat model by using a variety of retinal bioassays.

METHODS

hucMSCs were subjected to differential ultracentrifugation for the collection of exosomes, and transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA) using a NanoSight analysis system and Western blotting (WB) were used to analyze the expression of surface marker proteins such as CD63, CD9 and Calnexin. Streptozotocin (STZ) was injected into the intraperitoneal cavity to establish a diabetic model. Rats were divided into a normal group, diabetic group and hucMSC-Ex group. Fundus fluorescein angiography (FFA), optical coherence tomography (OCT) and other live imaging methods were used to observe the fundus of the rats. Finally, the eyeballs of rats from each group were collected for hematoxylin-eosin (HE) staining to further analyze the retinal structure.

RESULTS

Through TEM, NTA and WB, we successfully isolated hucMSC-Exs. Subsequent FFA and OCT confirmed that hucMSC-Exs effectively prevented early retinal vascular damage and thickening of the retina. Finally, HE staining of rat retinal sections revealed that exosomes effectively alleviated retinal structure disruption caused by diabetes.

CONCLUSION

hucMSC-Exs have a protective effect on the retina in diabetic rat through FFA, OCT and HE staining.

M1 Bone Marrow-Derived Macrophage-Derived Extracellular Vesicles Inhibit Angiogenesis and Myocardial Regeneration Following Myocardial Infarction via the MALAT1/MicroRNA-25-3p/CDC42 Axis

Myocardial infarction (MI) is a severe cardiovascular disease. Some M1 macrophage-derived extracellular vesicles (EVs) are involved in the inhibition of angiogenesis and acceleration dysfunction during MI. However, the potential mechanism of M1 phenotype bone marrow-derived macrophages- (BMMs-) EVs (M1-BMMs-EVs) in MI is largely unknown. This study sought to investigate whether M1-BMMs-EVs increased CDC42 expression and activated the MEK/ERK pathway by carrying lncRNA MALAT1 and competitively binding to miR-25-3p, thus inhibiting angiogenesis and myocardial regeneration after MI. After EV treatment, the cardiac function, infarct size, fibrosis, angiogenesis, and myocardial regeneration of MI mice and the viability, proliferation and angiogenesis of oxygen-glucose deprivation- (OGD-) treated myocardial microvascular endothelial cells (MMECs) were assessed. MALAT1 expression in MI mice, cells, and EVs was detected. MALAT1 downstream microRNAs (miRs), genes, and pathways were predicted and verified. MALAT1 and miR-25-3p were intervened to evaluate EV effects on OGD-treated cells. In MI mice, EV treatment aggravated MI and inhibited angiogenesis and myocardial regeneration. In OGD-treated cells, EV treatment suppressed cell viability, proliferation, and angiogenesis. MALAT1 was highly expressed in MI mice, OGD-treated MMECs, M1-BMMs, and EVs. Silencing MALAT1 weakened the inhibition of EV treatment on OGD-treated cells. MALAT1 sponged miR-25-3p to upregulate CDC42. miR-25-3p overexpression promoted OGD-treated cell viability, proliferation, and angiogenesis. The MEK/ERK pathway was activated after EV treatment. Collectively, M1-BMMs-EVs inhibited angiogenesis and myocardial regeneration following MI via the MALAT1/miR-25-3p/CDC42 axis and the MEK/ERK pathway activation.

Decellularized Whole-Organ Pre-vascularization: A Novel Approach for Organogenesis

Introduction: Whole-organ decellularization is an attractive approach for three-dimensional (3D) organ engineering. However, progress with this approach is hindered by intra-vascular blood coagulation that occurs after in vivo implantation of the re-cellularized scaffold, resulting in a short-term graft survival. In this study, we explored an alternative approach for 3D organ engineering through an axial pre-vascularization approach and examined its suitability for pancreatic islet transplantation. Methods: Whole livers from male Lewis rats were decellularized through sequential arterial perfusion of detergents. The decellularized liver scaffold was implanted into Lewis rats, and an arteriovenous bundle was passed through the scaffold. At the time of implantation, fresh bone marrow preparation (BM; n = 3), adipose-derived stem cells (ADSCs; n = 4), or HBSS (n = 4) was injected into the scaffold through the portal vein. After 5 weeks, around 2,600 islet equivalents (IEQs) were injected through the portal vein of the scaffold. The recipient rats were rendered diabetic by the injection of 65 mg/kg STZ intravenously 1 week before islet transplantation and were followed up after transplantation by measuring the blood glucose and body weight for 30 days. Intravenous glucose tolerance test was performed in the cured animals, and samples were collected for immunohistochemical (IHC) analyses. Micro-computed tomography (CT) images were obtained from one rat in each group for representation. Results: Two rats in the BM group and one in the ADSC group showed normalization of blood glucose levels, while one rat from each group showed partial correction of blood glucose levels. In contrast, no rats were cured in the HBSS group. Micro-CT showed evidence of sprouting from the arteriovenous bundle inside the scaffold. IHC analyses showed insulin-positive cells in all three groups. The number of von-Willebrand factor-positive cells in the islet region was higher in the BM and ADSC groups than in the HBSS group. The number of 5-bromo-2'-deoxyuridine-positive cells was significantly lower in the BM group than in the other two groups. Conclusions: Despite the limited numbers, the study showed the promising potential of the pre-vascularized whole-organ scaffold as a novel approach for islet transplantation. Both BM- and ADSCs-seeded scaffolds were superior to the acellular scaffold.

Angiogenic Effects and Crosstalk of Adipose-Derived Mesenchymal Stem/Stromal Cells and Their Extracellular Vesicles with Endothelial Cells

Adipose-derived mesenchymal stem/stromal cells (ASCs) are an adult stem cell population able to self-renew and differentiate into numerous cell lineages. ASCs provide a promising future for therapeutic angiogenesis due to their ability to promote blood vessel formation. Specifically, their ability to differentiate into endothelial cells (ECs) and pericyte-like cells and to secrete angiogenesis-promoting growth factors and extracellular vesicles (EVs) makes them an ideal option in cell therapy and in regenerative medicine in conditions including tissue ischemia. In recent angiogenesis research, ASCs have often been co-cultured with an endothelial cell (EC) type in order to form mature vessel-like networks in specific culture conditions. In this review, we introduce co-culture systems and co-transplantation studies between ASCs and ECs. In co-cultures, the cells communicate via direct cell-cell contact or via paracrine signaling. Most often, ASCs are found in the perivascular niche lining the vessels, where they stabilize the vascular structures and express common pericyte surface proteins. In co-cultures, ASCs modulate endothelial cells and induce angiogenesis by promoting tube formation, partly via secretion of EVs. In vivo co-transplantation of ASCs and ECs showed improved formation of functional vessels over a single cell type transplantation. Adipose tissue as a cell source for both mesenchymal stem cells and ECs for co-transplantation serves as a prominent option for therapeutic angiogenesis and blood perfusion in vivo.

The therapeutic triad of extracellular vesicles: As drug targets, as drugs, and as drug carriers

Rapidly growing interest in the study of extracellular vesicles (EVs) has led to the accumulation of evidence on their critical roles in various pathologies, as well as opportunities to design novel therapeutic EV-based applications. Efficiently exploiting the constantly expanding knowledge of the biology and function of EVs requires a deep understanding of the various possible strategies of using EVs for therapeutic purposes. Accordingly, in the present work, we have narrowed the broad therapeutic potential of EVs and consider the similarities and differences of various strategies as we articulate three major aspects (i.e., a triad) of their therapeutic uses: (i) EVs as drug targets, whereby we discuss therapeutic targeting of disease-promoting EVs; (ii) EVs as drugs, whereby we consider the natural medicinal properties of EVs and the available options for their optimization; and (iii) EVs as drug carriers, whereby we highlight the advantages of EVs as vehicles for efficacious drug delivery of natural compounds. Finally, after conducting a comprehensive review of the latest literature on each of these aspects, we outline opportunities, limitations, and potential solutions.

miR-4732-3p in Extracellular Vesicles From Mesenchymal Stromal Cells Is Cardioprotective During Myocardial Ischemia

Extracellular vesicles (EVs) derived from mesenchymal stromal cells (MSCs) are an emerging alternative to cell-based therapies to treat many diseases. However, the complexity of producing homogeneous populations of EVs in sufficient amount hampers their clinical use. To address these limitations, we immortalized dental pulp-derived MSC using a human telomerase lentiviral vector and investigated the cardioprotective potential of a hypoxia-regulated EV-derived cargo microRNA, miR-4732-3p. We tested the compared the capacity of a synthetic miR-4732-3p mimic with EVs to confer protection to cardiomyocytes, fibroblasts and endothelial cells against oxygen-glucose deprivation (OGD). Results showed that OGD-induced cardiomyocytes treated with either EVs or miR-4732-3p showed prolonged spontaneous beating, lowered ROS levels, and less apoptosis. Transfection of the miR-4732-3p mimic was more effective than EVs in stimulating angiogenesis in vitro and in vivo and in reducing fibroblast differentiation upon transforming growth factor beta treatment. Finally, the miR-4732-3p mimic reduced scar tissue and preserved cardiac function when transplanted intramyocardially in infarcted nude rats. Overall, these results indicate that miR-4732-3p is regulated by hypoxia and exerts cardioprotective actions against ischemic insult, with potential application in cell-free-based therapeutic strategies.

Role of miRNA-324-5p-Modified Adipose-Derived Stem Cells in Post-Myocardial Infarction Repair

Background and Objectives

To seek out the role of mircoRNA (miR)-324-5p-modified adipose-derived stem cells (ADSCs) in post-myocardial infarction (MI) myocardial repair.

Methods and Results

Rat ADSCs were cultivated and then identified by morphologic observation, osteogenesis and adipogenesis induction assays and flow cytometry. Afterwards, ADSCs were modified by miR-324-5p lentiviral vector, with ADSC proliferation and migration measured. Then, rat MI model was established, which was treated by ADSCs or miR-324-5p-modified ADSCs. Subsequently, the function of miR-324-5p-modified ADSCs in myocardial repair of MI rats was assessed through functional assays. Next, the binding relation of miR-324-5p and Toll-interacting protein (TOLLIP) was validated. Eventually, functional rescue assay of TOLLIP was performed to verify the role of TOLLIP in MI. First, rat ADSCs were harvested. Overexpressed miR-324-5p improved ADSC viability. ADSC transplantation moderately enhanced cardiac function of MI rats, reduced enzyme levels and decreased infarct size and apoptosis; while miR-324-5p-modified ADSCs could better promote post-MI repair. Mechanically, miR-324-5p targeted TOLLIP in myocardial tissues. Moreover, TOLLIP overexpression debilitated the promotive role of miR-324-5p-modified ADSCs in post-MI repair in rats.

Conclusions

miR-324-5p-modified ADSCs evidently strengthened post-MI myocardial repair by targeting TOLLIP in myocardial tissues.

Extracellular vesicles for tissue repair and regeneration: Evidence, challenges and opportunities

Extracellular vesicles (EVs) are biological nanoparticles naturally secreted by cells, acting as delivery vehicles for molecular messages. During the last decade, EVs have been assigned multiple functions that have established their potential as therapeutic mediators for a variety of diseases and conditions. In this review paper, we report on the potential of EVs in tissue repair and regeneration. The regenerative properties that have been associated with EVs are explored, detailing the molecular cargo they carry that is capable of mediating such effects, the signaling cascades triggered in target cells and the functional outcome achieved. EV interactions and biodistribution in vivo that influence their regenerative effects are also described, particularly upon administration in combination with biomaterials. Finally, we review the progress that has been made for the successful implementation of EV regenerative therapies in a clinical setting.

Mesenchymal stromal cell-derived exosomes in cardiac regeneration and repair

Mesenchymal stromal cell (MSC)-derived exosomes play a promising role in regenerative medicine. Their trophic and immunomodulatory potential has made them a promising candidate for cardiac regeneration and repair. Numerous studies have demonstrated that MSC-derived exosomes can replicate the anti-inflammatory, anti-apoptotic, and pro-angiogenic and anti-fibrotic effects of their parent cells and are considered a substitute for cell-based therapies. In addition, their lower tumorigenic risk, superior immune tolerance, and superior stability compared with their parent stem cells make them an attractive option in regenerative medicine. The therapeutic effects of MSC-derived exosomes have consequently been evaluated for application in cardiac regeneration and repair. In this review, we summarize the potential mechanisms and therapeutic effects of MSC-derived exosomes in cardiac regeneration and repair and provide evidence to support their clinical application.

The Application Potential and Advance of Mesenchymal Stem Cell-Derived Exosomes in Myocardial Infarction

Myocardial infarction (MI) is a devastating disease with high morbidity and mortality caused by the irreversible loss of functional cardiomyocytes and heart failure (HF) due to the restricted blood supply. Mesenchymal stem cells (MSCs) have been emerging as lead candidates to treat MI and subsequent HF mainly through secreting multitudinous factors of which exosomes act as the most effective constituent to boost the repair of heart function through carrying noncoding RNAs and proteins. Given the advantages of higher stability in the circulation, lower toxicity, and controllable transplantation dosage, exosomes have been described as a wonderful and promising cell-free treatment method in cardiovascular disease. Nowadays, MSC-derived exosomes have been proposed as a promising therapeutic approach to improve cardiac function and reverse heart remodeling. However, exosomes' lack of modification cannot result in desired therapeutic effect. Hence, optimized exosomes can be developed via various engineering methods such as pharmacological compound preconditioned MSCs, genetically modified MSCs, or miRNA-loaded exosomes and peptide tagged exosomes to improve the targeting and therapeutic effects of exosomes. The biological characteristics, therapeutic potential, and optimizing strategy of exosomes will be described in our review.

Extracellular Vesicles from Human Adipose-Derived Mesenchymal Stem Cells: A Review of Common Cargos

In recent years, the interest in adipose tissue mesenchymal cell–derived extracellular vesicles (AT-MSC-EVs) has increasingly grown. Numerous articles support the potential of human AT-MSC-EVs as a new therapeutic option for treatment of diverse diseases in the musculoskeletal and cardiovascular systems, kidney, skin, and immune system, among others. This approach makes use of the molecules transported inside of EVs, which play an important role in cell communication and in transmission of macromolecules. However, to our knowledge, there is no database where essential information about AT-MSC-EVs cargo molecules is gathered for easy reference. The aim of this study is to describe the different molecules reported so far in AT-MSC- EVs, their main molecular functions, and biological processes in which they are involved. Recently, the presence of 591 proteins and 604 microRNAs (miRNAs) has been described in human AT-MSC-EVs. The main molecular function enabled by both proteins and miRNAs present in human AT-MSC-EVs is the binding function. Signal transduction and gene silencing are the biological processes in which a greater number of proteins and miRNAs from human AT-MSC-EVs are involved, respectively. In this review we highlight the therapeutics effects of AT-MSC-EVs related with their participation in relevant biological processes including inflammation, angiogenesis, cell proliferation, apoptosis and migration, among others.

Differential Therapeutic Effect of Extracellular Vesicles Derived by Bone Marrow and Adipose Mesenchymal Stem Cells on Wound Healing of Diabetic Ulcers and Correlation to Their Cargoes

Extracellular vesicles (EVs) derived from mesenchymal stem cells isolated from both bone marrow (BMSCs) and adipose tissue (ADSCs) show potential therapeutic effects. These vesicles often show a similar beneficial effect on tissue regeneration, but in some contexts, they exert different biological properties. To date, a comparison of their molecular cargo that could explain the different biological effect is not available. Here, we demonstrated that ADSC-EVs, and not BMSC-EVs, promote wound healing on a murine model of diabetic wounds. Besides a general similarity, the bioinformatic analysis of their protein and miRNA cargo highlighted important differences between these two types of EVs. Molecules present exclusively in ADSC-EVs were highly correlated to angiogenesis, whereas those expressed in BMSC-EVs were preferentially involved in cellular proliferation. Finally, in vitro analysis confirmed that both ADSC and BMSC-EVs exploited beneficial effect on cells involved in skin wound healing such as fibroblasts, keratinocytes and endothelial cells, but through different cellular processes. Consistent with the bioinformatic analyses, BMSC-EVs were shown to mainly promote proliferation, whereas ADSC-EVs demonstrated a major effect on angiogenesis. Taken together, these results provide deeper comparative information on the cargo of ADSC-EVs and BMSC-EVs and the impact on regenerative processes essential for diabetic wound healing.

RETRACTED:BMSCs-derived exosomal microRNA-150-5p attenuates myocardial infarction in mice

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor-in-Chief. Concern was raised about the reliability of the Western blot results in Figs. 2B and 7B, which appear to have the same eyebrow shaped phenotype as many other publications tabulated here (https://docs.google.com/spreadsheets/d/149EjFXVxpwkBXYJOnOHb6RhAqT4a2llhj9LM60MBffM/edit#gid=0 [docs.google.com]). Concerns were also raised over the provenance of the flow cytometry plots in Fig. 1F. The journal requested the corresponding author comment on these concerns and provide the raw data. However, the authors were not responsive to the request for comment.  Since original data could not be provided, the overall validity of the results could not be confirmed. Therefore, the Editor-in-Chief decided to retract the article.

Extracellular Vesicles from Mesenchymal Stromal Cells for the Treatment of Inflammation-Related Conditions

Over the past two decades, mesenchymal stromal cells (MSCs) have demonstrated great potential in the treatment of inflammation-related conditions. Numerous early stage clinical trials have suggested that this treatment strategy has potential to lead to significant improvements in clinical outcomes. While promising, there remain substantial regulatory hurdles, safety concerns, and logistical issues that need to be addressed before cell-based treatments can have widespread clinical impact. These drawbacks, along with research aimed at elucidating the mechanisms by which MSCs exert their therapeutic effects, have inspired the development of extracellular vesicles (EVs) as anti-inflammatory therapeutic agents. The use of MSC-derived EVs for treating inflammation-related conditions has shown therapeutic potential in both in vitro and small animal studies. This review will explore the current research landscape pertaining to the use of MSC-derived EVs as anti-inflammatory and pro-regenerative agents in a range of inflammation-related conditions: osteoarthritis, rheumatoid arthritis, Alzheimer's disease, cardiovascular disease, and preeclampsia. Along with this, the mechanisms by which MSC-derived EVs exert their beneficial effects on the damaged or degenerative tissues will be reviewed, giving insight into their therapeutic potential. Challenges and future perspectives on the use of MSC-derived EVs for the treatment of inflammation-related conditions will be discussed.

[Significance of exosomes in cardiology: heralds of cardioprotection]

Los exosomas tienen un papel clave en la comunicación intercelular. Debido a sus múltiples interacciones, estas estructuras cumplen con el papel de «mensajeros» de forma dinámica, transportando su contenido a células blanco específicas y generando nuevas señales celulares. En este artículo se describen algunas de las proteínas, lípidos y ácidos nucleicos que son transportados por estas vesículas y que se han relacionado con cardioprotección, con la finalidad de proporcionar información y generar interés sobre la relevancia de los exosomas como posibles blancos diagnósticos y terapéuticos.

Tissue Regeneration Capacity of Extracellular Vesicles Isolated From Bone Marrow-Derived and Adipose-Derived Mesenchymal Stromal/Stem Cells

Mesenchymal stem cell (MSC)-based therapies have demonstrated tissue repair and regeneration capacity in various preclinical models. These therapeutic effects have recently been largely attributed to the paracrine effects of the MSC secretome, including proteins and extracellular vesicles (EVs). EVs are cell-secreted nano-sized vesicles with lipid bilayer membranes that facilitate cell–cell signaling. Treatments based on MSC-derived EVs are beginning to be explored as an alternative to MSC transplantation-based therapies. However, it remains to be determined which MSC source produces EVs with the greatest therapeutic potential. This review compares the tissue regeneration capacity of EVs isolated from the two most common clinical sources of adult MSCs, bone marrow and adipose tissue, with a particular focus on their angiogenic, osteogenic, and immunomodulatory potentials. Other important issues in the development of MSC-derived EV based therapies are also discussed.

Cardiac Adipose Tissue Contributes to Cardiac Repair: a Review

Cardiac adipose tissue is a metabolically active adipose tissue in close proximity to heart. Recent studies emphasized the benefits of cardiac adipose tissue in heart remodeling, such as reducing infarction size, enhancing neovascularization and regulating immune response, through a series of cellular mechanisms. In the present manuscript, we provide a comprehensive review regarding the role of cardiac adipose tissue in cardiac repair. We focus on different cardiac adipose tissues according to their distinguished anatomical structures. This review summarizes the latest evidence on the relationship between cardiac adipose tissue and cardiac repair. Cardiac adipose tissues (CAT) were systematically reviewed in the current manuscript which focused on the components of CAT, debates about cardiac adipose stem cells and their effect on heart.

Could Mesenchymal Stem Cell-Derived Exosomes Be a Therapeutic Option for Critically Ill COVID-19 Patients?

Coronavirus disease 2019 (COVID-19) is a pandemic viral disease originated in Wuhan, China, in December 2019, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The severe form of the disease is often associated with acute respiratory distress syndrome (ARDS), and most critically ill patients require mechanical ventilation and support in intensive care units. A significant portion of COVID-19 patients also develop complications of the cardiovascular system, primarily acute myocardial injury, arrhythmia, or heart failure. To date, no specific antiviral therapy is available for patients with SARS-CoV-2 infection. Exosomes derived from mesenchymal stem cells (MSCs) are being explored for the management of a number of diseases that currently have limited or no therapeutic options, thanks to their anti-inflammatory, immunomodulatory, and pro-angiogenic properties. Here, we briefly introduce the pathogenesis of SARS-CoV-2 and its implications in the heart and lungs. Next, we describe some of the most significant clinical evidence of the successful use of MSC-derived exosomes in animal models of lung and heart injuries, which might strengthen our hypothesis in terms of their utility for also treating critically ill COVID-19 patients.

Mesenchymal stem cell-derived exosomes: Toward cell-free therapeutic strategies in regenerative medicine

Mesenchymal stem cells (MSCs) are multipotent stem cells with marked potential for regenerative medicine because of their strong immunosuppressive and regenerative abilities. The therapeutic effects of MSCs are based in part on their secretion of biologically active factors in extracellular vesicles known as exosomes. Exosomes have a diameter of 30-100 nm and mediate intercellular communication and material exchange. MSC-derived exosomes (MSC-Exos) have potential for cell-free therapy for diseases of, for instance, the kidney, liver, heart, nervous system, and musculoskeletal system. Hence, MSC-Exos are an alternative to MSC-based therapy for regenerative medicine. We review MSC-Exos and their therapeutic potential for a variety of diseases and injuries.

Therapeutic applications of adipose cell-free derivatives: a review

BACKGROUND

Adipose-derived stem cells (ADSCs) have become one of the most utilized adult stem cells due to their abundance and accessibility. Recent studies have shown that paracrine cytokines, exosomes, and other active substances are the main factors through which ADSCs exert their biological effects.

MAIN BODY

Adipose cell-free derivatives have been recently gaining attention as potential therapeutic agents for various human diseases. These derivatives include ADSC-conditioned medium (ADSC-CM), ADSC exosomes (ADSC-Exo), and cell-free adipose tissue extracts (ATEs), all of which can be conveniently carried, stored, and transported. Currently, research on ADSC-conditioned medium (ADSC-CM) and ADSC exosomes (ADSC-Exo) is surging. Moreover, cell-free adipose tissue extracts (ATEs), obtained by purely physical methods, have emerged as the focus of research in recent years.

CONCLUSION

Adipose cell-free derivatives delivery can promote cell proliferation, migration, and angiogenesis, suppress cell apoptosis, and inflammation, as well as reduce oxidative stress and immune regulation. Thus, adipose cell-free derivatives have a broad therapeutic potential in many areas, as they possess anti-skin aging properties, promote wound healing, reduce scar formation, and provide myocardial protection and neuroprotection. This article summarizes these effects and reviews research progress in the use of adipose cell-free derivatives.

Exosomes from SIRT1-Overexpressing ADSCs Restore Cardiac Function by Improving Angiogenic Function of EPCs

Acute myocardial infarction (AMI) is one of the leading causes of mortality in cardiovascular diseases. The aim of this study was to investigate whether exosomes from Sirtuin 1 (SIRT1)-overexpressing adipose-derived stem cells (ADSCs) had a protective effect on AMI. The expression of C-X-C chemokine receptor type 7 (CXCR7) was significantly downregulated in peripheral blood endothelial progenitor cells (EPCs) from AMI patients (AMI-EPCs) compared with that in healthy donors, which coincided with impaired tube formation. The exosomes from SIRT1 overexpression in ADSCs (ADSCs-SIRT1-Exos) increased the expression of C-X-C motif chemokine 12 (CXCL12) and nuclear factor E2 related factor 2 (Nrf2) in AMI-EPCs, which promoted migration and tube formation of AMI-EPCs, and overexpression of CXCR7 helped AMI-EPCs to restore the function of cell migration and tube formation. Moreover, CXCR7 was downregulated in the myocardium of AMI mice, and knockout of CXCR7 exacerbated AMI-induced impairment of cardiovascular function. Injection of ADSCs-SIRT1-Exos increased the survival and promoted the recovery of myocardial function with reduced infarct size and post-AMI left ventricular remodeling, induced vasculogenesis, and decreased AMI-induced myocardial inflammation. These findings showed that ADSCs-SIRT1-Exos may recruit EPCs to the repair area and that this recruitment may be mediated by Nrf2/CXCL12/CXCR7 signaling.

Novel Applications of Mesenchymal Stem Cell-derived Exosomes for Myocardial Infarction Therapeutics

Cardiovascular diseases (CVDs) are the leading cause of mortality and morbidity globally, representing approximately a third of all deaths every year. The greater part of these cases is represented by myocardial infarction (MI), or heart attack as it is better known, which occurs when declining blood flow to the heart causes injury to cardiac tissue. Mesenchymal stem cells (MSCs) are multipotent stem cells that represent a promising vector for cell therapies that aim to treat MI due to their potent regenerative effects. However, it remains unclear the extent to which MSC-based therapies are able to induce regeneration in the heart and even less clear the degree to which clinical outcomes could be improved. Exosomes, which are small extracellular vesicles (EVs) known to have implications in intracellular communication, derived from MSCs (MSC-Exos), have recently emerged as a novel cell-free vector that is capable of conferring cardio-protection and regeneration in target cardiac cells. In this review, we assess the current state of research of MSC-Exos in the context of MI. In particular, we place emphasis on the mechanisms of action by which MSC-Exos accomplish their therapeutic effects, along with commentary on the current difficulties faced with exosome research and the ongoing clinical applications of stem-cell derived exosomes in different medical contexts.

Combination of olfactory ensheathing cells and human umbilical cord mesenchymal stem cell-derived exosomes promotes sciatic nerve regeneration

Olfactory ensheathing cells (OECs) are promising seed cells for nerve regeneration. However, their application is limited by the hypoxic environment usually present at the site of injury. Exosomes derived from human umbilical cord mesenchymal stem cells have the potential to regulate the pathological processes that occur in response to hypoxia. The ability of OECs to migrate is unknown, especially in hypoxic conditions, and the effect of OECs combined with exosomes on peripheral nerve repair is not clear. Better understanding of these issues will enable the potential of OECs for the treatment of nerve injury to be addressed. In this study, OECs were acquired from the olfactory bulb of Sprague Dawley rats. Human umbilical cord mesenchymal stem cell-derived exosomes (0–400 μg/mL) were cultured with OECs for 12–48 hours. After culture with 400 μg/mL exosomes for 24 hours, the viability and proliferation of OECs were significantly increased. We observed changes to OECs subjected to hypoxia for 24 hours and treatment with exosomes. Exosomes significantly promoted the survival and migration of OECs in hypoxic conditions, and effectively increased brain-derived neurotrophic factor gene expression, protein levels and secretion. Finally, using a 12 mm left sciatic nerve defect rat model, we confirmed that OECs and exosomes can synergistically promote motor and sensory function of the injured sciatic nerve. These findings show that application of OECs and exosomes can promote nerve regeneration and functional recovery. This study was approved by the Institutional Ethical Committee of the Air Force Medical University, China (approval No. IACUC-20181004) on October 7, 2018; and collection and use of human umbilical cord specimens was approved by the Ethics Committee of the Linyi People’s Hospital, China (approval No. 30054) on May 20, 2019.