Enhanced cell survival and paracrine effects of mesenchymal stem cells overexpressing hepatocyte growth factor promote cardioprotection in myocardial infarction

Modification of mesenchymal stromal cells with silibinin-loaded PLGA nanoparticles improves their therapeutic efficacy for cutaneous wound repair

The use of mesenchymal stromal cells (MSCs) for treating chronic inflammatory disorders, wounds, and ischemia-reperfusion injuries has shown improved healing efficacy. However, the poor survival rate of transplanted cells due to oxidative stress in injured or inflamed tissue remains a significant concern for MSC-based therapies. In this study, we developed a new approach to protect MSCs from oxidative stress, thereby improving their survival in a wound microenvironment and enhancing their therapeutic effect. We produced PLGA nanoparticles loaded with the cytoprotective phytochemical silibinin (SBN), and used them to modify MSCs. Upon internalization, these nanoformulations released SBN, activating the Nrf2/ARE signaling pathway, resulting in threefold reduction in intracellular ROS content and improved cell survival under oxidative stress conditions. Modification of MSCs with SBN-loaded PLGA nanoparticles increased their survival upon transplantation to full-thickness cutaneous wounds and improved wound healing. This study suggests that MSC modification with cytoprotective nanoparticles could be a promising approach for improving wound healing.

In silico Mechanics of Stem Cells Intramyocardially Transplanted with a Biomaterial Injectate for Treatment of Myocardial Infarction

PURPOSE

Biomaterial and stem cell delivery are promising approaches to treating myocardial infarction. However, the mechanical and biochemical mechanisms underlying the therapeutic benefits require further clarification. This study aimed to assess the deformation of stem cells injected with the biomaterial into the infarcted heart.

METHODS

A microstructural finite element model of a mid-wall infarcted myocardial region was developed from ex vivo microcomputed tomography data of a rat heart with left ventricular infarct and intramyocardial biomaterial injectate. Nine cells were numerically seeded in the injectate of the microstructural model. The microstructural and a previously developed biventricular finite element model of the same rat heart were used to quantify the deformation of the cells during a cardiac cycle for a biomaterial elastic modulus (Einj) ranging between 4.1 and 405,900 kPa.

RESULTS

The transplanted cells' deformation was largest for Einj = 7.4 kPa, matching that of the cells, and decreased for an increase and decrease in Einj. The cell deformation was more sensitive to Einj changes for softer (Einj ≤ 738 kPa) than stiffer biomaterials.

CONCLUSIONS

Combining the microstructural and biventricular finite element models enables quantifying micromechanics of transplanted cells in the heart. The approach offers a broader scope for in silico investigations of biomaterial and cell therapies for myocardial infarction and other cardiac pathologies.

Mesenchymal stromal cells for improvement of cardiac function following acute myocardial infarction: a matter of timing

Acute myocardial infarction (AMI) is the leading cause of cardiovascular death and remains the most common cause of heart failure. Reopening of the occluded artery, i.e., reperfusion, is the only way to save the myocardium. However, the expected benefits of reducing infarct size are disappointing due to the reperfusion paradox, which also induces specific cell death. These ischemia-reperfusion (I/R) lesions can account for up to 50% of final infarct size, a major determinant for both mortality and the risk of heart failure (morbidity). In this review, we provide a detailed description of the cell death and inflammation mechanisms as features of I/R injury and cardioprotective strategies such as ischemic postconditioning as well as their underlying mechanisms. Due to their biological properties, the use of mesenchymal stromal/stem cells (MSCs) has been considered a potential therapeutic approach in AMI. Despite promising results and evidence of safety in preclinical studies using MSCs, the effects reported in clinical trials are not conclusive and even inconsistent. These discrepancies were attributed to many parameters such as donor age, in vitro culture, and storage time as well as injection time window after AMI, which alter MSC therapeutic properties. In the context of AMI, future directions will be to generate MSCs with enhanced properties to limit cell death in myocardial tissue and thereby reduce infarct size and improve the healing phase to increase postinfarct myocardial performance.

Human umbilical cord mesenchymal stem cell-derived exosomes combined with gelatin methacryloyl hydrogel to promote fractional laser injury wound healing

To investigate whether human umbilical cord mesenchymal stem cell-derived exosomes combined with gelatin methacryloyl (GelMA) hydrogel are beneficial in promoting healing of laser-injured skin wounds in mice. Supernatants of cultured human umbilical cord mesenchymal stem cells (HUC-MSCs) were collected to obtain human umbilical cord MSC-derived exosomes (HUC-MSCs-Exos), which were combined with GelMA hydrogel complex to treat a mouse fractional laser injury model. The study was divided into PBS group, EX (HUC-MSCs-Exos) group, GEL (GelMA hydrogel) group and EX+GEL (HUC-MSCs-Exos combined with GelMA hydrogel) group. The healing of laser-injured skin in each group was observed by gross view and dermatoscopy, and changes in skin structure, angiogenesis and proliferation-related indexes were observed during the healing process of laser-injured skin in each group. The results of the animal experiments showed that the EX and GEL groups alone and the EL+EX group exhibited less inflammatory response compared to the PBS group. The EX and GEL groups showed marked tissue proliferation and favourable angiogenesis, which promoted the wound healing well. The GEL+EX group had the most significant promotion of wound healing compared to the PBS group. qPCR results showed that the expression levels of proliferation-related factors, including KI67 and VEGF and angiogenesis-related factor CD31, were significantly higher in the GEL+EX group than in the other groups, with a time-dependent effect. The combination of HUC-MSCs-Exos and GelMA hydrogel is beneficial in reducing the early inflammatory response of laser-injured skin in mice and promoting its proliferation and angiogenesis, which in turn promotes wound healing.

Poly(ethylene glycol)-Based Hydrogel Microcarriers Alter Secretory Activity of Genetically Modified Mesenchymal Stromal Cells

In order to scale up culture therapeutic cells, such as mesenchymal stromal cells (MSCs), culture in suspension bioreactors using microcarriers (μCs) is preferred. However, the impact of microcarrier type on the resulting MSC secretory activity has not been investigated. In this study, two poly(ethylene glycol) hydrogel formulations with different swelling ratios (named "stiffer" and "softer") were fabricated as μC substrates to culture MSCs and MSCs genetically modified to express the interleukin-1 receptor antagonist (IL-1Ra-MSCs). Changes in cell number, secretory and angiogenic activity, and changes in MAPK signaling were evaluated when cultured on hydrogel μCs, as well as on tissue culture plastic-based Synthemax μCs. We demonstrated that culture on stiffer μCs increased secretion of IL-1Ra compared to culture on Synthemax μCs by IL-1Ra-MSCs by 1.2- to 1.6-fold, as well as their in vitro angiogenic activity, compared to culture on Synthemax μCs, while culture on both stiffer and softer μCs altered the secretion of several other factors compared to culture on Synthemax μCs. Changes in angiogenic activity corresponded with increased gene expression and secretion of hepatocyte growth factor by MSCs cultured on softer μCs by 2.5- to 6-fold compared to MSCs cultured on Synthemax μCs. Quantification of phosphoprotein signaling with the MAPK pathway revealed broad reduction of pathway activation by IL-1Ra-MSCs cultured on both stiffer and softer μCs compared to Synthemax, where phosphorylated c-Jun, ATF2, and MEK1 were reduced specifically on softer μCs. Overall, this study showed that μC surfaces can influence the secretory activity of genetically modified MSCs and identified associated changes in MAPK pathway signaling, which is a known central regulator of cytokine secretion.

Enhancing mesenchymal stem cell survival and homing capability to improve cell engraftment efficacy for liver diseases

Although mesenchymal stem cell (MSC) transplantation provides an alternative strategy for end-stage liver disease (ESLD), further widespread application of MSC therapy is limited owing to low cell engraftment efficiency. Improving cell engraftment efficiency plays a critical role in enhancing MSC therapy for liver diseases. In this review, we summarize the current status and challenges of MSC transplantation for ESLD. We also outline the complicated cell-homing process and highlight how low cell engraftment efficiency is closely related to huge differences in extracellular conditions involved in MSC homing journeys ranging from constant, controlled conditions in vitro to variable and challenging conditions in vivo. Improving cell survival and homing capabilities enhances MSC engraftment efficacy. Therefore, we summarize the current strategies, including hypoxic priming, drug pretreatment, gene modification, and cytokine pretreatment, as well as splenectomy and local irradiation, used to improve MSC survival and homing capability, and enhance cell engraftment and therapeutic efficiency of MSC therapy. We hope that this review will provide new insights into enhancing the efficiency of MSC engraftment in liver diseases.

Advantages of mesenchymal stem cell over the other stem cells

A stem cell is a particular group of cells that has the extraordinary potential to convert within the body into particular cell types. They are used to regenerate tissues and cells in the body that have been damaged or destroyed by the disease. Stem cells come in three different varieties: adult stem cells, embryonic stem cells and induced pluripotent stem cells (iPSCs). Embryonic stem cells have a high chance of immune rejection and also have ethical dilemmas and iPSCs have genetic instability. Adult stem cells are difficult to analyze and extract for research since they are frequently insufficient in native tissues. However, mesenchymal stem cells (MSC) one of the categories of adult stem cells are stromal cells with a variety of potentials that can differentiate into a wide range of cell types. MSCs can be transplanted into a variety of people without worrying about rejection because they have demonstrated the ability to prevent an adverse reaction from the immune system. These transplants have powerful anti-inflammatory and immunosuppressive effects and greatly enhance the body's inherent healing capacity. While MSCs do not offer treatment for illnesses, the idea behind them is to enable the body to recover sufficiently for a protracted reduction in symptoms. In many cases, this is sufficient to significantly enhance the patient's well-being. Inspite of several advantages some potential long-term concerns connected to MSC therapy are maldifferentiation, immunosuppression and cancerous tumor growth. In this review, we will compare the mesenchymal stem cells with other stem cells with respect to the source of origin, their properties and therapeutic applications, and discuss the MSC's disadvantages.

Recent advances in the therapeutic efficacy of hepatocyte growth factor gene-modified mesenchymal stem cells in multiple disease settings

Mesenchymal stem cell (MSC) therapy is considered a new treatment for a wide range of diseases and injuries, but challenges remain, such as poor survival, homing and engraftment rates, thus limiting the therapeutic efficacy of the transplanted MSCs. Many strategies have been developed to enhance the therapeutic efficacy of MSCs, such as preconditioning, co-transplantation with graft materials and gene modification. Hepatocyte growth factor (HGF) is secreted by MSCs, which plays an important role in MSC therapy. It has been reported that the modification of the HGF gene is beneficial to the therapeutic efficacy of MSCs, including diseases of the heart, lung, liver, urinary system, bone and skin, lower limb ischaemia and immune-related diseases. This review focused on studies involving HGF/MSCs both in vitro and in vivo. The characteristics of HGF/MSCs were summarized, and the mechanisms of their improved therapeutic efficacy were analysed. Furthermore, some insights are provided for HGF/MSCs' clinical application based on our understanding of the HGF gene and MSC therapy.

Engineered extracellular vesicles and their mimics in cardiovascular diseases

Cardiovascular diseases (CVDs) are the leading cause of death worldwide. Current pharmacological interventions for the CVDs suffer from low bioavailability, low retention rate, poor targeting, drug resistance complicated side effects. Extracellular vesicles (EVs), which are lipid vesicles secreted by cells, play key roles in pathological processes of CVDs. Engineered EVs and EV mimics with superior properties can overcome limitations of traditional medicine, thus emerging as alternative therapeutic options for the CVDs. In this Review, we summarized basic concepts of EVs and EV mimics, highlighted engineering strategies, and lastly discussed applications of engineered EVs and EV mimics against the CVDs. We believe this Review can provide some new insights on engineering EVs and EV mimics and facilitate their application in precise control of CVDs.

Mechanotransduction in Mesenchymal Stem Cells (MSCs) Differentiation: A Review

Mechanotransduction is the process by which physical force is converted into a biochemical signal that is used in development and physiology; meanwhile, it is intended for the ability of cells to sense and respond to mechanical forces by activating intracellular signals transduction pathways and the relative phenotypic adaptation. It encompasses the role of mechanical stimuli for developmental, morphological characteristics, and biological processes in different organs; the response of cells to mechanically induced force is now also emerging as a major determinant of disease. Due to fluid shear stress caused by blood flowing tangentially across the lumen surface, cells of the cardiovascular system are typically exposed to a variety of mechanotransduction. In the body, tissues are continuously exposed to physical forces ranging from compression to strain, which is caused by fluid pressure and compressive forces. Only lately, though, has the importance of how forces shape stem cell differentiation into lineage-committed cells and how mechanical forces can cause or exacerbate disease besides organizing cells into tissues been acknowledged. Mesenchymal stem cells (MSCs) are potent mediators of cardiac repair which can secret a large array of soluble factors that have been shown to play a huge role in tissue repair. Differentiation of MSCs is required to regulate mechanical factors such as fluid shear stress, mechanical strain, and the rigidity of the extracellular matrix through various signaling pathways for their use in regenerative medicine. In the present review, we highlighted mechanical influences on the differentiation of MSCs and the general factors involved in MSCs differentiation. The purpose of this study is to demonstrate the progress that has been achieved in understanding how MSCs perceive and react to their mechanical environment, as well as to highlight areas where more research has been performed in previous studies to fill in the gaps.

Apelin-13 Pretreatment Promotes the Cardioprotective Effect of Mesenchymal Stem Cells against Myocardial Infarction by Improving Their Survival

Although mesenchymal stem cell- (MSC-) based therapy has shown promising results for myocardial infarction (MI), low cell survival heavily limits its beneficial effects. Apelin plays an essential regulatory role in cell proliferation. This study was aimed at determining whether Apelin-13 pretreatment could improve the survival of MSCs in the ischemic heart and enhance their cardioprotective efficacy against MI. MSCs were pretreated with or without Apelin-13 for 24 hours and then exposed to serum deprivation and hypoxia (SD/H) for 48 hours. The mitochondrial morphology of MSCs was assessed by MitoTracker staining. The apoptosis of MSCs was determined by TUNEL staining. The level of mitochondrial reactive oxygen species (ROS) of MSCs was detected by Mito-Sox staining. MSCs and Apelin-13-pretreated MSCs were transplanted into the peri-infarct region in a mouse MI model. Apelin-13 pretreatment protected MSCs against SD/H-induced mitochondrial fragmentation and apoptosis. Apelin-13 pretreatment reduced ROS generation induced by SD/H in MSCs. Furthermore, Apelin-13 pretreatment enhanced the angiogenesis of MSCs under SD/H conditions. Mechanistically, Apelin-13 pretreatment inhibited SD/H-induced MSC apoptosis by downregulating mitochondrial fission via activation of the ERK pathway, and these effects were partially abrogated by ERK inhibitor U0126. Apelin-13 pretreatment promoted the survival of MSCs in the ischemic heart. Moreover, transplantation with Apelin-13-pretreated MSCs improved heart function and increased angiogenesis accompanied by decreased fibrosis compared with MSC transplantation at 28 days following MI. These findings reveal that pretreatment with Apelin-13 improves MSCs survival and enhances their therapeutic efficacy for MI. Our study provides a novel approach to improve MSC-based therapy for cardiovascular disease.

Mesenchymal Stem Cell (MSCs) Therapy for Ischemic Heart Disease: A Promising Frontier

Although tremendous progress has been made in conventional treatment for ischemic heart disease, it still remains a major cause of death and disability. Cell-based therapeutics holds an exciting frontier of research for complete cardiac recuperation. The capacity of diverse stem and progenitor cells to stimulate cardiac renewal has been analysed, with promising results in both pre-clinical and clinical trials. Mesenchymal stem cells have been ascertained to have regenerative ability via a variety of mechanisms, including differentiation from the mesoderm lineage, immunomodulatory properties, and paracrine effects. Also, their availability, maintenance, and ability to replenish endogenous stem cell niches have rendered them suitable for front-line research. This review schemes to outline the use of mesenchymal stem cell therapeutics for ischemic heart disease, their characteristics, the potent mechanisms of mesenchymal stem cell-based heart regeneration, and highlight preclinical data. Additionally, we discuss the results of the clinical trials to date as well as ongoing clinical trials on ischemic heart disease.

Emerging Trends in Mesenchymal Stem Cells Applications for Cardiac Regenerative Therapy: Current Status and Advances

Irreversible myocardium infarction is one of the leading causes of cardiovascular disease (CVD) related death and its quantum is expected to grow in coming years. Pharmacological intervention has been at the forefront to ameliorate injury-related morbidity and mortality. However, its outcomes are highly skewed. As an alternative, stem cell-based tissue engineering/regenerative medicine has been explored quite extensively to regenerate the damaged myocardium. The therapeutic modality that has been most widely studied both preclinically and clinically is based on adult multipotent mesenchymal stem cells (MSC) delivered to the injured heart. However, there is debate over the mechanistic therapeutic role of MSC in generating functional beating cardiomyocytes. This review intends to emphasize the role and use of MSC in cardiac regenerative therapy (CRT). We have elucidated in detail, the various aspects related to the history and progress of MSC use in cardiac tissue engineering and its multiple strategies to drive cardiomyogenesis. We have further discussed with a focus on the various therapeutic mechanism uncovered in recent times that has a significant role in ameliorating heart-related problems. We reviewed recent and advanced technologies using MSC to develop/create tissue construct for use in cardiac regenerative therapy. Finally, we have provided the latest update on the usage of MSC in clinical trials and discussed the outcome of such studies in realizing the full potential of MSC use in clinical management of cardiac injury as a cellular therapy module.

Therapeutic Mesenchymal Stem/Stromal Cells: Value, Challenges and Optimization

Cellular therapy aims to replace damaged resident cells by restoring cellular and molecular environments suitable for tissue repair and regeneration. Among several candidates, mesenchymal stem/stromal cells (MSCs) represent a critical component of stromal niches known to be involved in tissue homeostasis. In vitro, MSCs appear as fibroblast-like plastic adherent cells regardless of the tissue source. The therapeutic value of MSCs is being explored in several conditions, including immunological, inflammatory and degenerative diseases, as well as cancer. An improved understanding of their origin and function would facilitate their clinical use. The stemness of MSCs is still debated and requires further study. Several terms have been used to designate MSCs, although consensual nomenclature has yet to be determined. The presence of distinct markers may facilitate the identification and isolation of specific subpopulations of MSCs. Regarding their therapeutic properties, the mechanisms underlying their immune and trophic effects imply the secretion of various mediators rather than direct cellular contact. These mediators can be packaged in extracellular vesicles, thus paving the way to exploit therapeutic cell-free products derived from MSCs. Of importance, the function of MSCs and their secretome are significantly sensitive to their environment. Several features, such as culture conditions, delivery method, therapeutic dose and the immunobiology of MSCs, may influence their clinical outcomes. In this review, we will summarize recent findings related to MSC properties. We will also discuss the main preclinical and clinical challenges that may influence the therapeutic value of MSCs and discuss some optimization strategies.

The therapeutic potential of adipose tissue-derived mesenchymal stromal cells in the treatment of busulfan-induced azoospermic mice

PURPOSE

The generation of germ cells from mesenchymal stromal cells (MSCs) provides a valuable in vitro platform for infertility modeling. The establishment of these cells is a new approach for assisted reproductive technology (ART) to help infertile patients who lack functional gametes.

METHODS

Human adipose-derived MSCs were isolated and then characterized for multipotency by flow cytometry, differentiation capacity, and cytogenetic assays. These cells were used in a male germ cell differentiation study. The expression of male germ cell markers was evaluated at day 21 of differentiation using an immunofluorescence assay, flow cytometry, and RT-qPCR. Undifferentiated MSCs were used for transplantation in busulfan-induced azoospermic mice.

RESULTS

In this study, MSCs were successfully isolated from human adipose tissues which were positive for cell markers such as CD90, CD105, CD73, and CD29 but negative for CD34 and CD45. The results of flow cytometry, immunocytochemistry, and RT-qPCR analysis at day 21 of differentiation showed that the undifferentiated adipose-derived MSCs are able to differentiate into male germ cells. Additionally, transplantation of undifferentiated MSCs in busulfan-induced azoospermic mice caused spermatogenesis recovery in the majority of seminiferous tubules.

CONCLUSION

In this study, we showed that differentiation of human adipose-derived MSCs into male germ cells is a useful tool for in vitro study of human germ cell development. Our results demonstrated that cell therapy with adipose-derived MSCs could help the repair of pathological changes in testicular seminiferous tubules. Therefore, it may have a clinical application for the treatment of azoospermia in infertile patients.

Hopes and Hurdles of Employing Mesenchymal Stromal Cells in the Treatment of Cardiac Fibrosis

Excessive cardiac fibrosis plays a crucial role in almost all types of heart disease. Generally, cardiac fibrosis is a scarring process triggered in response to stress, injury, or aging and is characterized by the accumulation of activated myofibroblasts that deposit high levels of extracellular matrix proteins in the myocardium. While it is beneficial for cardiac repair in the short term, it can also result in pathological remodeling, tissue stiffening, and cardiac dysfunction, contributing to the progression of heart failure, arrhythmia, and sudden cardiac death. Despite its high prevalence, there is a lack of effective and safe therapies that specifically target myofibroblasts to inhibit or even reverse pathological cardiac fibrosis. In the past few decades, cell therapy has been under continuous evaluation as a potential treatment strategy, and several studies have shown that transplantation of mesenchymal stromal cells (MSCs) can reduce cardiac fibrosis and improve heart function. Mechanistically, it is believed that the heart benefits from MSC therapy by stimulating innate anti-fibrotic and regenerative reactions. The mechanisms of action include paracrine signaling and cell-to-cell interactions. In this review, we provide an overview of the anti-fibrotic properties of MSCs and approaches to enhance them and discuss future directions of MSCs for the treatment of cardiac fibrosis.

Umbilical cord mesenchymal stem/stromal cells potential to treat organ disorders; an emerging strategy

Currently, mesenchymal stem/stromal cells (MSCs) have attracted growing attention in the context of cell-based therapy in regenerative medicine. Following the first successful procurement of human MSCs from bone marrow (BM), these cells isolation has been conducted from various origins, in particular, the umbilical cord (UC). Umbilical cord-derived mesenchymal stem/stromal cells (UC-MSCs) can be acquired by a non-invasive plan and simply cultured, and thereby signifies their superiority over MSCs derived from other sources for medical purposes. Due to their unique attributes, including self-renewal, multipotency, and accessibility concomitant with their immunosuppressive competence and lower ethical concerns, UC-MSCs therapy is described as encouraging therapeutic options in cell-based therapies. Regardless of their unique aptitude to adjust inflammatory response during tissue recovery and delivering solid milieu for tissue restoration, UC-MSCs can be differentiated into a diverse spectrum of adult cells (e.g., osteoblast, chondrocyte, type II alveolar, hepatocyte, and cardiomyocyte). Interestingly, they demonstrate a prolonged survival and longer telomeres compared with MSCs derived from other sources, suggesting that UC-MSCs are desired source to use in regenerative medicine. In the present review, we deliver a brief review of UC-MSCs isolation, expansion concomitantly with immunosuppressive activities, and try to collect and discuss recent pre-clinical and clinical researches based on the use of UC-MSCs in regenerative medicine, focusing on with special focus on in vivo researches.

Comparing the Therapeutic Potential of Stem Cells and their Secretory Products in Regenerative Medicine

Cell therapy involves the transplantation of human cells to replace or repair the damaged tissues and modulate the mechanisms underlying disease initiation and progression in the body. Nowadays, many different types of cell-based therapy are developed and used to treat a variety of diseases. In the past decade, cell-free therapy has emerged as a novel approach in regenerative medicine after the discovery that the transplanted cells exerted their therapeutic effect mainly through the secretion of paracrine factors. More and more evidence showed that stem cell-derived secretome, i.e., growth factors, cytokines, and extracellular vesicles, can repair the injured tissues as effectively as the cells. This finding has spurred a new idea to employ secretome in regenerative medicine. Despite that, will cell-free therapy slowly replace cell therapy in the future? Or are these two modes of treatment still needed to address different diseases and conditions? This review provides an indepth discussion about the values of stem cells and secretome in regenerative medicine. In addition, the safety, efficacy, advantages, and disadvantages of using these two modes of treatment in regenerative medicine are also critically reviewed.

The application of umbilical cord-derived MSCs in cardiovascular diseases

Transplantation of stem cells is a promising, emerging treatment for cardiovascular diseases in the modern era. Mesenchymal stem cells (MSCs) derived from the umbilical cord are one of the most promising cell sources because of their capacity for differentiation into cardiomyocytes, endothelial cells and vascular smooth muscle cells in vitro/in vivo. In addition, umbilical cord‐derived MSCs (UC‐MSCs) secrete many effective molecules regulating apoptosis, fibrosis and neovascularization. Another important and specific characteristic of UC‐MSCs is their low immunogenicity and immunomodulatory properties. However, the application of UC‐MSCs still faces some challenges, such as low survivability and tissue retention in a harmful disease environment. Gene engineering and pharmacological studies have been implemented to overcome these difficulties. In this review, we summarize the differentiation ability, secretion function, immunoregulatory properties and preclinical/clinical studies of UC‐MSCs, highlighting the advantages of UC‐MSCs for the treatment of cardiovascular diseases.

Mesenchymal Stem Cells as a Gene Delivery Tool: Promise, Problems, and Prospects

The cell-based approach in gene therapy arises as a promising strategy to provide safe, targeted, and efficient gene delivery. Owing to their unique features, as homing and tumor-tropism, mesenchymal stem cells (MSCs) have recently been introduced as an encouraging vehicle in gene therapy. Nevertheless, non-viral transfer of nucleic acids into MSCs remains limited due to various factors related to the main stakeholders of the process (e.g., nucleic acids, carriers, or cells). In this review, we have summarized the main types of nucleic acids used to transfect MSCs, the pros and cons, and applications of each. Then, we have emphasized on the most efficient lipid-based carriers for nucleic acids to MSCs, their main features, and some of their applications. While a myriad of studies have demonstrated the therapeutic potential for engineered MSCs therapy in various illnesses, optimization for clinical use is an ongoing challenge. On the way of improvement, genetically modified MSCs have been combined with various novel techniques and tools (e.g., exosomes, spheroids, 3D-Bioprinting, etc.,) aiming for more efficient and safe applications in biomedicine.

The Vital Roles of Mesenchymal Stem Cells and the Derived Extracellular Vesicles in Promoting Angiogenesis After Acute Myocardial Infarction

Acute myocardial infarction (AMI) is an event of ischemic myocardial necrosis caused by acute coronary artery occlusion, which ultimately leads to a large loss of cardiomyocytes. The prerequisite of salvaging ischemic myocardium and improving cardiac function of patients is to provide adequate blood perfusion in the infarcted area. Apart from reperfusion therapy, it is also urgent and imperative to promote angiogenesis. Recently, growing evidence based on promising preclinical data indicates that mesenchymal stem cells (MSCs) can provide therapeutic effects on AMI by promoting angiogenesis. Extracellular vesicles (EVs), membrane-encapsulated vesicles with complex cargoes, including proteins, nucleic acids, and lipids, can be derived from MSCs and represent part of their functions, so EVs also possess the ability to promote angiogenesis. However, poor control of the survival and localization of MSCs hindered clinical transformation and made scientists start looking for new approaches based on MSCs. Identifying the role of MSCs and their derived EVs in promoting angiogenesis can provide a theoretical basis for improved MSC-based methods, and ultimately promote the clinical treatment of AMI. This review highlights potential proangiogenic mechanisms of transplanted MSCs and the derived EVs after AMI and summarizes the latest literature concerning the novel methods based on MSCs to maximize the angiogenesis capability.

The emerging therapeutic role of mesenchymal stem cells in anthracycline-induced cardiotoxicity

Mesenchymal stem cell (MSC)-based tissue regeneration therapy has been extensively investigated for cardiac regeneration over the past two decades. Numerous animal and clinical investigations demonstrated the efficacy of various types of MSCs towards myocardial protection and restoration against anthracycline-induced cardiotoxicity (AIC). It has been established that local or systemic administration of MSCs considerably improved the cardiac function, while ameliorating inflammatory responses and myocardial fibrosis. Several factors influence the outcomes of MSC treatment for AIC, including MSC types, dosages, and routes and duration of administration. In this review, we discuss the recent (from 2015 to 2020) experimental and clinical research on the preventive and regeneration efficacy of different types of MSCs (with or without supporting agents) against AIC, as well as the key factors responsible for MSC-mediated cardiac repair. In addition, challenges and future perspectives of MSC-based cardiac regeneration therapy are also outlined.

Tissue Failure Propagation as Mediated by Circulatory Flow

Aging is driven by subcellular processes that are relatively well understood. However, the qualitative mechanisms and quantitative dynamics of how these micro-level failures cascade to a macro-level catastrophe in a tissue or organs remain largely unexplored. Here, we experimentally and theoretically study how cell failure propagates in an engineered tissue in the presence of advective flow. We argue that cells secrete cooperative factors, thereby forming a network of interdependence governed by diffusion and flow, which fails with a propagating front parallel to advective circulation.

The preventative effect of bone marrow-derived mesenchymal stem cell exosomes on urethral stricture in rats

Background

Urethral stricture (US) is a major challenge in urology and there is an urgent need for effective therapies for its treatment. Exosomes derived from bone marrow mesenchymal stem cells (BMSCs-Exos) have been shown to be effective in preventing scar and fibrosis formation after tissue injury. However, the potential utility of BMSCs-Exos in the prevention of US remains unknown. We hypothesized that local administration of BMSCs-Exos may influence urethral healing and scar formation in a rat model of US.

Methods

A previously established model of rat US was used in this study. Sprague Dawley rats were randomly assigned into sham, US, and US + BMSCs-Exos groups. Micro-ultrasound assessment, histopathology, immunohistochemistry, and gene expression analysis were performed at four weeks post-surgery.

Results

US rats exhibited thick urethral walls with a narrowed lumen, when compared with sham rats. However, these changes were suppressed in the US + BMSCs-Exos group. The preventative effects of BMSCs-Exos on US formation were also apparent histologically. US + BMSCs-Exos rats demonstrated decreased expression of several fibrosis-related genes in urethral tissues, including Col I, fibronectin, and elastin, when compared with US rats. BMSCs-Exos treatment also led to an increase in the expression of angiogenesis-related genes in these tissues, including VEGF, eNOS, and bFGF.

Conclusions

Our findings therefore demonstrate that the local administration of BMSCs-Exos prevents urethral stricture formation by regulating fibrosis and angiogenesis. These findings provide a basis for an innovative strategy involving the clinical application of exosomes to counteract US formation.

Preconditioned and Genetically Modified Stem Cells for Myocardial Infarction Treatment

Ischemic heart disease and myocardial infarction remain leading causes of mortality worldwide. Existing myocardial infarction treatments are incapable of fully repairing and regenerating the infarcted myocardium. Stem cell transplantation therapy has demonstrated promising results in improving heart function following myocardial infarction. However, poor cell survival and low engraftment at the harsh and hostile environment at the site of infarction limit the regeneration potential of stem cells. Preconditioning with various physical and chemical factors, as well as genetic modification and cellular reprogramming, are strategies that could potentially optimize stem cell transplantation therapy for clinical application. In this review, we discuss the most up-to-date findings related to utilizing preconditioned stem cells for myocardial infarction treatment, focusing mainly on preconditioning with hypoxia, growth factors, drugs, and biological agents. Furthermore, genetic manipulations on stem cells, such as the overexpression of specific proteins, regulation of microRNAs, and cellular reprogramming to improve their efficiency in myocardial infarction treatment, are discussed as well.

Biomaterials functionalized with MSC secreted extracellular vesicles and soluble factors for tissue regeneration

The therapeutic benefits of mesenchymal stromal cell (MSC) transplantation have been attributed to their secreted factors, including extracellular vesicles (EVs) and soluble factors. The potential of employing the MSC secretome as an alternative acellular approach to cell therapy is being investigated in various tissue injury indications, but EVs administered via bolus injections are rapidly sequestered and cleared. However, biomaterials offer delivery platforms to enhance EV retention rates and healing efficacy. In this review, we highlight the mechanisms underpinning the therapeutic effects of MSC-EVs and soluble factors as effectors of immunomodulation and tissue regeneration, conferred primarily via their nucleic acid and protein contents. We discuss how manipulating the cell culture microenvironment or genetic modification of MSCs can further augment the potency of their secretions. The most recent advances in the development of EV-functionalized biomaterials that mediate enhanced angiogenesis and cell survival, while attenuating inflammation and fibrosis, are presented. Finally, some technical challenges to be considered for the clinical translation of biomaterials carrying MSC-secreted bioactive cargo are discussed.

Umbilical cord mesenchymal stromal cells engraft and transdifferentiate into cardiomyocyte-like cells following acute myocardial ischemia⋆

OBJECTIVE

Human umbilical cord-derived mesenchymal stromal cells (hUC-MSCs) gained importance in acute/chronic ischemic cardiomyopathy because of their outstanding regenerative potential in various pathologic conditions. The present study was designed to determine to what extent hUC-MSCs contribute to myocardial regeneration in acute experimental myocardial infarction (MI) in rats.

METHODS

Animals were assigned into two groups; the control group received intramyocardial PBS injections, while the hUC-MSC group received calcein-AM-labeled 8.8 × 10⁶/kg hUC-MSCs. Three weeks following the acute MI induction, rats were sacrificed after assessing the left ventricular (LV) function using echocardiography. For the assessment of infarct size, the triphenyl tetrazolium chloride (TTC) test was used in isolated hearts. Collagen-rich scar tissue was demonstrated using Masson's trichrome staining, followed by the detection of cardiac troponin I (cTnI), α-sarcomeric actin (α-SA), von Willebrand factor (vWF), CD68 and CD206 expressions in control and cell-injected sections.

RESULTS

Echocardiography revealed a significant difference (P = 0.037) in the LV ejection fraction between groups. TTC assays demonstrated a significant difference (P = 0.006) between the groups regarding the ratio of the infarcted LV area. Calcein-AM-loaded cells were identified mostly in ischemic myocardium. Transplanted cells also expressed human-specific cTnI, providing concrete proof of transdifferentiation into cardiomyocytes, and α-SA. vWF⁺ cells verified the neovascularization in the ischemic myocardium. Finally, a slight shift from pro-inflammatory to anti-inflammatory macrophages (CD68⁺/CD206⁺) was noted in both groups.

CONCLUSIONS

We found that the intramyocardial transplanted hUC-MSCs engrafted and partially transdifferentiated into cardiomyocytes, reduced scar formation, and induced angiogenesis through the association of pro/anti-inflammatory macrophages.

Genetic Engineering as a Strategy to Improve the Therapeutic Efficacy of Mesenchymal Stem/Stromal Cells in Regenerative Medicine

Mesenchymal stem/stromal cells (MSCs) have been widely studied in the field of regenerative medicine for applications in the treatment of several disease settings. The therapeutic potential of MSCs has been evaluated in studies in vitro and in vivo, especially based on their anti-inflammatory and pro-regenerative action, through the secretion of soluble mediators. In many cases, however, insufficient engraftment and limited beneficial effects of MSCs indicate the need of approaches to enhance their survival, migration and therapeutic potential. Genetic engineering emerges as a means to induce the expression of different proteins and soluble factors with a wide range of applications, such as growth factors, cytokines, chemokines, transcription factors, enzymes and microRNAs. Distinct strategies have been applied to induce genetic modifications with the goal to enhance the potential of MCSs. This review aims to contribute to the update of the different genetically engineered tools employed for MSCs modification, as well as the factors investigated in different fields in which genetically engineered MSCs have been tested.

Long noncoding RNA UCA1 from hypoxia-conditioned hMSC-derived exosomes: a novel molecular target for cardioprotection through miR-873-5p/XIAP axis

Exosomes (Exo) secreted from mesenchymal stem cells (hMSCs) are protective against myocardial injury. The purpose of the study was to investigate the role and mechanisms by which exosomes promote cardiomyocyte survival and function following myocardial infarction (MI). hMSCs were cultured under hypoxic and normoxic conditions. Hypoxia-conditioned hMSC-derived exosomes (Hypo-Exo) and normoxic-conditioned hMSC-derived exosomes (Nor-Exo) were collected and intramyocardially injected into rats with MI. The therapeutic effects of Hypo-Exo and Nor-Exo were evaluated after 4 weeks. Quantitative real-time PCR (qRT-PCR) was used to detect the expression of candidate long noncoding RNA urothelial carcinoma associated 1 (lncRNA-UCA1) in Nor-Exo and Hypo-Exo. Intramyocardial injection of lncRNA-UCA1-knockdown-Hypo-Exo in a rat model of MI was then performed and the cardiac function was characterized. The target and downstream of the molecular mechanism lncRNA-UCA1 was disclosed by luciferase reporter assays and western blot. Circulating exosomal lncRNA-UCA1 level in AMI patients and healthy volunteers was assessed. We found that (1) hMSC exosomal (from hypoxic and normoxic conditions) cardioprotection in vitro and in vivo correlated with the presence of encapsulated lncRNA-UCA1 in exosomes; (2) lncRNA-UCA1 targeted miR-873 via sponging, reducing the latter’s suppressive effects on its target XIAP, and this translated into AMPK phosphorylation and increased level of the antiapoptotic protein BCL2; and (3) plasma derived from patients with AMI contained exosomes enriched with the lncRNA-UCA1, unlike that from normal subjects. This study demonstrates that Hypo-Exo lncRNA-UCA1 plays a cardioprotective role via the miR-873-5p/XIAP axis and circulating exosomal lncRNA-UCA1 may be a promising novel biomarker for the diagnosis of AMI.

Human umbilical cord MSC-derived hepatocyte growth factor enhances autophagy in AOPP-treated HK-2 cells

Mesenchymal stem cell (MSC) transplantation may serve as an important treatment modality in chronic kidney disease (CKD); however, the underlying mechanisms remain unclear. Advanced oxidation protein products (AOPP) have been demonstrated to induce renal tubular epithelial cell (RTEC) injury via autophagy inhibition. Therefore, the present study was performed to investigate the role of human umbilical cord-derived MSCs (hUC-MSCs) in RTEC autophagy. AOPP-treated HK-2 cells were co-cultured with hUC-MSCs or treated with recombinant humanized hepatocyte growth factor (HGF). Western blotting was used to detect the levels of autophagy-and PI3K/AKT/mTOR signaling pathway-related proteins, and immunofluorescence staining was used to detect the levels of autophagy-related proteins. The HGF protein levels in HK-2 cells and the hUC-MSC co-culture system were measured. The cells were subsequently treated with tivantinib, an HGF competitive inhibitor, and the levels of autophagy-related proteins were detected. Microtubule-associated protein 1 light chain 3B (LC3B) II/LC3B I (LC3II/LC3I) and beclin 1 protein levels were increased, while p62, PI3K, phosphorylated (p)-AKT and the p-mTOR protein levels were decreased in AOPP-treated HK-2 cells co-cultured with hUC-MSC, compared with the group treated with AOPP only. Furthermore, HGF expression was increased in AOPP-treated HK-2 cells co-cultured with hUC-MSC, compared with the group treated with AOPP alone. When HGF activity was inhibited using tivantinib, these effects on LC3II/LC3I, beclin 1, p62, PI3K, p-AKT, and p-mTOR expression were partially reversed. Furthermore, the effects of tivantinib were reversed by Ly294002. In conclusion, the present study revealed that hUC-MSCs partially reversed AOPP-mediated inhibition of autophagy in HK-2 cells via secretion of HGF, indicating that hUC-MSCs may serve as a potential therapy for preventing the progression of CKD.

Exosomes: Carriers of Pro-Fibrotic Signals and Therapeutic Targets in Fibrosis

Exosomes are nano-sized extracellular vesicles that are released by a variety of cells. Exosomes contain cargo from cells they derived, including lipids, proteins and nucleic acids. The bilayer lipid membrane structure of exosomes protects these contents from degradation, allowing them for intercellular communication. The role of exosomes in fibrotic diseases is increasingly being valued. Exosomes, as carriers of profibrotic signals, are involved in the development of fibrotic diseases, and also regulate fibrosis by transmitting signals that inhibit fibrosis or inflammation. Exosomes mobilize and activate a range of effector cells by targeted delivery of bioactive information. Exosomes can also reflect the condition of cells, tissues and organisms, and thus become potential biomarkers of fibrotic diseases. Exosomes from bone marrow stem cells support biological signaling that regulates and inhibits fibrosis and thus initially used in the treatment of fibrotic diseases. This article briefly summarizes the role of exosomes in the pathogenesis and treatment of fibrotic diseases and raises some issues that remain to be resolved.

Transfer of mitochondria from mesenchymal stem cells derived from induced pluripotent stem cells attenuates hypoxia-ischemia-induced mitochondrial dysfunction in PC12 cells

Mitochondrial dysfunction in neurons has been implicated in hypoxia-ischemia-induced brain injury. Although mesenchymal stem cell therapy has emerged as a novel treatment for this pathology, the mechanisms are not fully understood. To address this issue, we first co-cultured 1.5 × 10⁵ PC12 cells with mesenchymal stem cells that were derived from induced pluripotent stem cells at a ratio of 1:1, and then intervened with cobalt chloride (CoCl₂) for 24 hours. Reactive oxygen species in PC12 cells was measured by Mito-sox. Mitochondrial membrane potential (?Ψm) in PC12 cells was determined by JC-1 staining. Apoptosis of PC12 cells was detected by terminal deoxynucleotidal transferase-mediated dUTP nick end-labeling staining. Mitochondrial morphology in PC12 cells was examined by transmission electron microscopy. Transfer of mitochondria from the mesenchymal stem cells derived from induced pluripotent stem cells to damaged PC12 cells was measured by flow cytometry. Mesenchymal stem cells were induced from pluripotent stem cells by lentivirus infection containing green fluorescent protein in mitochondria. Then they were co-cultured with PC12 cells in Transwell chambers and treated with CoCl₂ for 24 hours to detect adenosine triphosphate level in PC12 cells. CoCl₂-induced PC12 cell damage was dose-dependent. Co-culture with mesenchymal stem cells significantly reduced apoptosis and restored ?Ψm in the injured PC12 cells under CoCl₂ challenge. Co-culture with mesenchymal stem cells ameliorated mitochondrial swelling, the disappearance of cristae, and chromatin margination in the injured PC12 cells. After direct co-culture, mitochondrial transfer from the mesenchymal stem cells stem cells to PC12 cells was detected via formed tunneling nanotubes between these two types of cells. The transfer efficiency was greatly enhanced in the presence of CoCl₂. More importantly, inhibition of tunneling nanotubes partially abrogated the beneficial effects of mesenchymal stem cells on CoCl₂-induced PC12 cell injury. Mesenchymal stem cells reduced CoCl₂-induced PC12 cell injury and these effects were in part due to efficacious mitochondrial transfer.

Improved therapeutics of modified mesenchymal stem cells: an update

Background

Mesenchymal stromal cells (MSCs) have attracted intense interest due to their powerful intrinsic properties of self-regeneration, immunomodulation and multi-potency, as well as being readily available and easy to isolate and culture. Notwithstanding, MSC based therapy suffers reduced efficacy due to several challenges which include unfavorable microenvironmental factors in vitro and in vivo.

Body

In the quest to circumvent these challenges, several modification techniques have been applied to the naïve MSC to improve its inherent therapeutic properties. These modification approaches can be broadly divided into two groups to include genetic modification and preconditioning modification (using drugs, growth factors and other molecules). This field has witnessed great progress and continues to gather interest and novelty. We review these innovative approaches in not only maintaining, but also enhancing the inherent biological activities and therapeutics of MSCs with respect to migration, homing to target site, adhesion, survival and reduced premature senescence. We discuss the application of the improved modified MSC in some selected human diseases. Possible ways of yet better enhancing the therapeutic outcome and overcoming challenges of MSC modification in the future are also elaborated.

Conclusion

The importance of prosurvival and promigratory abilities of MSCs in their therapeutic applications can never be overemphasized. These abilities are maintained and even further enhanced via MSC modifications against the inhospitable microenvironment during culture and transplantation. This is a turning point in MSC-based therapy with promising preclinical studies and higher future prospect.

Exosomes from mesenchymal stem cells overexpressing MIF enhance myocardial repair

Accumulating evidence has shown that mesenchymal stem cell (MSC)-derived exosomes (exo) mediate cardiac repair following myocardial infarction (MI). Macrophage migration inhibitory factor (MIF), a proinflammatory cytokine, plays a critical role in regulating cell homeostasis. This study aimed to investigate the cardioprotective effects of exo secreted from bone marrow-MSCs (BM-MSCs) overexpressing MIF in a rat model of MI. MIF plasmid was transducted in BM-MSCs. Exo were isolated from the supernatants of BM-MSCs and MIF-BM-MSCs, respectively. The morphology of mitochondria in neonatal mice cardiomyocytes (NRCMs) was determined by MitoTracker staining. The apoptosis of NRCMs was examined by deoxynucleotidyl transferase-mediated dUTP nick end-labeling. BM-MSC-exo and MIF-BM-MSC-exo were intramuscularly injected into the peri-infarct region in a rat model of MI. The heart function of rats was assessed by echocardiography. The expression of MIF was greatly enhanced in MIF-BM-MSCs compared with BM-MSCs. Both BM-MSC-exo and MIF-BM-MSC-exo expressed CD63 and CD81. NRCMs treated with MIF-BM-MSC-exo exhibited less mitochondrial fragmentation and cell apoptosis under hypoxia/serum deprivation (H/SD) challenge than those treated with BM-MSC-exo via activating adenosine 5'-monophosphate-activated protein kinase signaling. Moreover, these effects were partially abrogated by Compound C. Injection of BM-MSC-exo or MIF-BM-MSC-exo greatly restored heart function in a rat model of MI. Compared with BM-MSC-exo, injection of MIF-BM-MSC-exo was associated with enhanced heart function, reduced heart remodeling, less cardiomyocyte mitochondrial fragmentation, reactive oxygen species generation, and apoptosis. Our study reveals a new mechanism of MIF-BM-MSC-exo-based therapy for MI and provides a novel strategy for cardiovascular disease treatment.

Transplantation of hMSCs Genome Edited with LEF1 Improves Cardio-Protective Effects in Myocardial Infarction

Stem cell-based therapy is one of the most attractive approaches to ischemic heart diseases, such as myocardial infarction (MI). We evaluated the cardio-protective effects of the human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSCs) stably expressing lymphoid enhancer-binding factor 1 (LEF1; LEF1/hUCB-MSCs) in a rat model of MI. LEF1 overexpression in hUCB-MSCs promoted cell-proliferation and anti-apoptotic effects in hypoxic conditions. For the application of its therapeutic effects in vivo, the LEF1 gene was introduced into an adeno-associated virus integration site 1 (AAVS1) locus, known as a safe harbor site on chromosome 19 by CRISPR/Cas9-mediated gene integration in hUCB-MSCs. Transplantation of LEF1/hUCB-MSCs onto the infarction region in the rat model significantly improved overall survival. The cardio-protective effect of LEF1/hUCB-MSCs was proven by echocardiogram parameters, including greatly improved left-ventricle ejection fraction (EF) and fractional shortening (FS). Moreover, histology and immunohistochemistry successfully presented reduced MI region and fibrosis by LEF1/hUCB-MSCs. We found that these overall positive effects of LEF1/hUCB-MSCs are attributed by increased proliferation and survival of stem cells in oxidative stress conditions and by the secretion of various growth factors by LEF1. In conclusion, this study suggests that the stem cell-based therapy, conjugated with genome editing of transcription factor LEF1, which promotes cell survival, could be an effective therapeutic strategy for cardiovascular disease.

Mesenchymal Stem Cells: The Past Present and Future

The biomedical applications of mesenchymal stem cells (MSCs) have gained expanding attention over the past three decades. MSCs are easily obtained from various tissue types (e.g. bone marrow, fat, cord blood, etc.), are capable of self-renewal, and could be induced to differentiate into several cell lineages for countless biomedical applications. In addition, when transplanted, MSCs are not detected by immune surveillance, thus do not lead to graft rejection. Moreover, they can home towards affected tissues and induce their therapeutic effect in a cell-base and/or a cell-free manner. These properties, and many others, have made MSCs appealing therapeutic cell candidates (for cell and/or gene therapy) in myriad clinical conditions. However, similar to any other therapeutic tool, MSCs still have their own limitations and grey areas that entail more research for better understanding and optimization. Herein, we present a brief overview of various pre-clinical/clinical applications of MSCs in regenerative medicine and discuss limitations and future challenges.

Useful applications of growth factors for cardiovascular regenerative medicine

Novel advances for cardiovascular diseases (CVDs) include regenerative approaches for fibrosis, hypertrophy, and neoangiogenesis. Studies indicate that growth factor (GF) signaling could promote heart repair since most of the evidence is derived from preclinical models. Observational studies have evaluated GF serum/plasma levels as feasible biomarkers for risk stratification of CVDs. Noteworthy, two clinical interventional published studies showed that the administration of growth factors (GFs) induced beneficial effect on left ventricular ejection fraction (LVEF), myocardial perfusion, end-systolic volume index (ESVI). To date, large scale ongoing studies are in Phase I-II and mostly focussed on intramyocardial (IM), intracoronary (IC) or intravenous (IV) administration of vascular endothelial growth factor (VEGF) and fibroblast growth factor-23 (FGF-23) which result in the most investigated GFs in the last 10 years. Future data of ongoing randomized controlled studies will be crucial in understanding whether GF-based protocols could be in a concrete way effective in the clinical setting.

Anti-fibrotic mechanisms of exogenously-expanded mesenchymal stromal cells for fibrotic diseases

Most chronic diseases involving inflammation have a fibrotic component that involves remodeling and excess accumulation of extracellular matrix components. Left unchecked, fibrosis leads to organ failure and death. Mesenchymal stromal cells (MSCs) are emerging as a potent cell-based therapy for a wide spectrum of fibrotic conditions due to their immunomodulatory, anti-inflammatory and anti-fibrotic properties. This review provides an overview of known mechanisms by which MSCs mediate their anti-fibrotic actions and in relation to animal models of pulmonary, liver, renal and cardiac fibrosis. Recent MSC clinical trials results in liver, lung, skin, kidney and hearts are discussed and next steps for future MSC-based therapies including pre-activated or genetically-modified cells, or extracellular vesicles are also considered.

Haemin pre-treatment augments the cardiac protection of mesenchymal stem cells by inhibiting mitochondrial fission and improving survival

The cardiac protection of mesenchymal stem cell (MSC) transplantation for myocardial infarction (MI) is largely hampered by low cell survival. Haem oxygenase 1 (HO‐1) plays a critical role in regulation of cell survival under many stress conditions. This study aimed to investigate whether pre‐treatment with haemin, a potent HO‐1 inducer, would promote the survival of MSCs under serum deprivation and hypoxia (SD/H) and enhance the cardioprotective effects of MSCs in MI. Bone marrow (BM)‐MSCs were pretreated with or without haemin and then exposed to SD/H. The mitochondrial morphology of MSCs was determined by MitoTracker staining. BM‐MSCs and haemin‐pretreated BM‐MSCs were transplanted into the peri‐infarct region in MI mice. SD/H induced mitochondrial fragmentation, as shown by increased mitochondrial fission and apoptosis of BM‐MSCs. Pre‐treatment with haemin greatly inhibited SD/H‐induced mitochondrial fragmentation and apoptosis of BM‐MSCs. These effects were partially abrogated by knocking down HO‐1. At 4 weeks after transplantation, compared with BM‐MSCs, haemin‐pretreated BM‐MSCs had greatly improved the heart function of mice with MI. These cardioprotective effects were associated with increased cell survival, decreased cardiomyocytes apoptosis and enhanced angiogenesis. Collectively, our study identifies haemin as a regulator of MSC survival and suggests a novel strategy for improving MSC‐based therapy for MI.

Incorporation of small extracellular vesicles in sodium alginate hydrogel as a novel therapeutic strategy for myocardial infarction

Bone marrow mesenchymal stem cell (MSC)-derived small extracellular vesicles (sEVs) have been widely used for treating myocardial infarction (MI). However, low retention and short-lived therapeutic effects are still significant challenges. This study aimed to determine whether incorporation of MSC-derived sEVs in alginate hydrogel increases their retention in the heart thereby improving therapeutic effects.

Methods: The optimal sodium alginate hydrogel incorporating sEVs system was determined by its release ability of sEVs and rheology of hydrogel. Ex vivo fluorescence imaging was utilized to evaluate the retention of sEVs in the heart. Immunoregulation and effects of sEVs on angiogenesis were analyzed by immunofluorescence staining. Echocardiography and Masson's trichrome staining were used to estimate cardiac function and infarct size.

Results: The delivery of sEVs incorporated in alginate hydrogel (sEVs-Gel) enhanced their retention in the heart. Compared with sEVs only treatment (sEVs), sEVs-Gel treatment significantly decreased cardiac cell apoptosis and promoted the polarization of macrophages at day 3 after MI. sEVs-Gel treatment also increased scar thickness and angiogenesis at four weeks post-infarction. Measurement of cardiac function and infarct size were significantly better in the sEVs-Gel group than in the group treated with sEVs only.

Conclusion: Delivery of sEVs incorporated in alginate hydrogel provides a novel approach of cell-free therapy and optimizes the therapeutic effect of sEVs for MI.

C1q/tumor necrosis factor-related protein-3-engineered mesenchymal stromal cells attenuate cardiac impairment in mice with myocardial infarction

Mesenchymal stromal cells (MSCs) transplantation offers an attractive alternative in myocardial infarctive therapy. However, poor cell engraftment and survival limit their restorative capacity. C1q/tumor necrosis factor-related protein-3 (CTRP3) inhibits reverse remodeling after myocardial infarction (MI) and was found to be secreted by MSCs in our preliminary experiments. We examined whether the overexpression of CTRP3 improved the survival of transplanted MSCs and augmented their efficacy on MI and whether silencing CTRP3 attenuated these effects. For gain-of-function analysis, MSCs overexpressing CTRP3 (LvC3-MSCs), control virus-transfected MSCs (LvNull-MSCs), MSCs alone, or phosphate-buffered saline (PBS) were injected into the peripheral areas of the infarction immediately after coronary artery ligation. For loss-of-function analysis, mice subjected to MI were randomized into groups and administered CTRP3-knockdown MSCs (LvshC3-MSCs), Lvshctrl-MSCs, MSCs, or PBS. Survival rates, cardiac function, and myocardial remodeling in mice were evaluated after 4 weeks. Injection of MSCs or LvNull-MSCs improved the left ventricular ejection fraction, inhibited cardiac fibrosis, and regulated cellular profiles of the infarction border zone 4 weeks after MI compared with those in the PBS group. Furthermore, overexpression of hCTRP3 promoted the efficacy of MSCs in the treatment of MI. However, knocking down CTRP3 impaired that. Coculture experiments confirmed that hCTRP3-enriched conditioned medium (CM) promoted MSCs migration and protected against H₂O₂-induced cell damage. Conversely, CM from C3^−/− MSCs (CTRP3 knock out) significantly reduced the migration and antioxidative effects of MSCs. CTRP3 protein alone promoted MSCs proliferation and migration by upregulating matrix metalloproteinase 9 (MMP9) and protecting against oxidation by increasing superoxide dismutase 2 (SOD2) and metallothionein 1/2 (MT1/2) expression; and these effects were blocked by pretreatment with the extracellular signal-regulated kinase (ERK1/2) inhibitor U0126. Overexpression of CTRP3 significantly improved the MSCs-based efficacy on MI by increasing cell survival and retention via a mechanism involving ERK1/2-MMP9 and ERK1/2-SOD2/MT1/2 signaling.

Ameliorating the Fibrotic Remodeling of the Heart through Direct Cardiac Reprogramming

Coronary artery disease is the most common form of cardiovascular diseases, resulting in the loss of cardiomyocytes (CM) at the site of ischemic injury. To compensate for the loss of CMs, cardiac fibroblasts quickly respond to injury and initiate cardiac remodeling in an injured heart. In the remodeling process, cardiac fibroblasts proliferate and differentiate into myofibroblasts, which secrete extracellular matrix to support the intact structure of the heart, and eventually differentiate into matrifibrocytes to form chronic scar tissue. Discovery of direct cardiac reprogramming offers a promising therapeutic strategy to prevent/attenuate this pathologic remodeling and replace the cardiac fibrotic scar with myocardium in situ. Since the first discovery in 2010, many progresses have been made to improve the efficiency and efficacy of reprogramming by understanding the mechanisms and signaling pathways that are activated during direct cardiac reprogramming. Here, we overview the development and recent progresses of direct cardiac reprogramming and discuss future directions in order to translate this promising technology into an effective therapeutic paradigm to reverse cardiac pathological remodeling in an injured heart.

Effects of cobalt chloride on the stem cell marker expression and osteogenic differentiation of stem cells from human exfoliated deciduous teeth

Stem cells from human exfoliated deciduous teeth (SHEDs) are a promising source for tissue engineering and stem cell transplantation. However, long-term in vitro culture and expansion lead to the loss of stemness of SHEDs, compromising their therapeutic benefits. Hypoxia plays an essential role in controlling the stem cell behavior of mesenchymal stem cells (MSCs). Thus, this study aimed to investigate the effects of cobalt chloride (CoCl2), a hypoxia-mimetic agent, on the stem cell marker expression and osteogenic differentiation of SHEDs. SHEDs were cultured with or without 50 or 100 μM CoCl2. Their proliferation, apoptosis, stem cell marker expression, migration ability, and osteogenic differentiation were examined. Culture with 50 and 100 μM CoCl2 increased the hypoxia-inducible factor-1 alpha (HIF-1α) protein levels in a dose-dependent manner in SHEDs without inducing significant cytotoxicity. This effect was accompanied by an increase in the proportion of STRO-1+ cells. CoCl2 significantly increased the expression of stem cell markers (OCT4, NANOG, SOX2, and c-Myc) in a dose-dependent manner. The migration ability was also promoted by CoCl2 treatment. Furthermore, SHEDs cultured in osteogenic medium with CoCl2 showed a dose-dependent reduction in alkaline phosphatase (ALP) activity and calcium deposition. The expression of osteogenic-related genes was also suppressed by CoCl2, especially in the 100-μM CoCl2 group. In conclusion, CoCl2 increased the expression of stem cell markers and inhibited the osteogenic differentiation of SHEDs. These findings may provide evidence supporting the use of in vitro hypoxic environments mimicked by CoCl2 in assisting the clinical application of SHEDs.

Paracrine Mechanisms Involved in Mesenchymal Stem Cell Differentiation into Cardiomyocytes

Cardiovascular Disease (CVD) is one of the world-wide healthcare problem that involves the heart or blood vessels. CVD includes myocardial infarction and coronary artery diseases (CAD). Dysfunctional myocardial cells are leading causes of low cardiac output or ventricular dysfunction after cardiac arrest and may contribute to the progression of CVD which could not generate new cardiomyocytes in human adult heart. The mesenchymal stem cells (MSCs) which are present in adult marrow can self-renew and have the capacity of differentiation into multiple types of cells including cardiomyocytes. Recent biochemical analyses greatly revealed that several regulators of MSCs, such as HGF, PDGF, Wnt, and Notch-1 signaling pathways have been shown to be involved in the proliferation and differentiation into cardiomyocytes. Preclinical studies are paving the way for further applications of MSCs in the repair of myocardial infarction. In this study, we discuss and summarize the paracrine mechanisms involved in MSCs differentiation into cardiomyocytes.

Toward Regeneration of the Heart: Bioengineering Strategies for Immunomodulation

Myocardial Infarction (MI) is the most common cardiovascular disease. An average-sized MI causes the loss of up to 1 billion cardiomyocytes and the adult heart lacks the capacity to replace them. Although post-MI treatment has dramatically improved survival rates over the last few decades, more than 20% of patients affected by MI will subsequently develop heart failure (HF), an incurable condition where the contracting myocardium is transformed into an akinetic, fibrotic scar, unable to meet the body's need for blood supply. Excessive inflammation and persistent immune auto-reactivity have been suggested to contribute to post-MI tissue damage and exacerbate HF development. Two newly emerging fields of biomedical research, immunomodulatory therapies and cardiac bioengineering, provide potential options to target the causative mechanisms underlying HF development. Combining these two fields to develop biomaterials for delivery of immunomodulatory bioactive molecules holds great promise for HF therapy. Specifically, minimally invasive delivery of injectable hydrogels, loaded with bioactive factors with angiogenic, proliferative, anti-apoptotic and immunomodulatory functions, is a promising route for influencing the cascade of immune events post-MI, preventing adverse left ventricular remodeling, and offering protection from early inflammation to fibrosis. Here we provide an updated overview on the main injectable hydrogel systems and bioactive factors that have been tested in animal models with promising results and discuss the challenges to be addressed for accelerating the development of these novel therapeutic strategies.

Functionally Improved Mesenchymal Stem Cells to Better Treat Myocardial Infarction

Myocardial infarction (MI) is one of the leading causes of death worldwide. Mesenchymal stem cell (MSC) transplantation is considered a promising approach and has made significant progress in preclinical studies and clinical trials for treating MI. However, hurdles including poor survival, retention, homing, and differentiation capacity largely limit the therapeutic effect of transplanted MSCs. Many strategies such as preconditioning, genetic modification, cotransplantation with bioactive factors, and tissue engineering were developed to improve the survival and function of MSCs. On the other hand, optimizing the hostile transplantation microenvironment of the host myocardium is also of importance. Here, we review the modifications of MSCs as well as the host myocardium to improve the efficacy of MSC-based therapy against MI.

A new method for neonatal rat ventricular myocyte purification using superparamagnetic iron oxide particles

BACKGROUND

Neonatal rat ventricular myocytes (NRVMs) have proven to be an ideal research model for cardiac disease. However, the current methods to purify NRVMs have a limitation to obtain high purity. The purpose of this study was to develop a NRVM purification method by using superparamagnetic iron oxide particles (SIOP).

METHODS

NRVMs were purified by using SIOP (SIOP group). The differential attachment with or without bromodeoxyuridine (BrdU) treatment served as control and BrdU groups, respectively. The Percoll gradient (Percoll) and magnetic-activated cell sorting (MACS) methods were performed to compare the purity and viability of NRVMs with SIOP method.

RESULTS

The SIOP group enriched NRVMs up to 93.9 ± 2.0% purity determined by flow cytometry (FCM) and 95.6 ± 1.3% by immunofluorescence count (IF). In contrast, the control group gave purities of 71.9 ± 2.9% (by FCM) and 66.8 ± 8.9% (by IF), and the BrdU group obtained 82.0 ± 1.3% (by FCM) and 83.1 ± 2.4% (by IF). The purity of SIOP-isolated NRVMs was not different from that of Percoll and MACS groups. However, the cardiomyocytes separated by these methods, except SIOP protocol, were mixed with intrinsic cardiac adrenergic cells. NRVMs purified by SIOP shaped the similar three-dimensional morphology, with no difference in cell yield, viability and cytosolic Ca²⁺ homeostasis at 24 h after isolation compared with NRVMs in other groups. Furthermore, SIOP-purified NRVMs retained the responses to phenylephrine and lipopolysaccharide challenge.

CONCLUSION

We first reported an efficient and novel method to purify NRVMs using SIOP, which may help accelerate innovative research in the field of cardiomyocyte biology.

Extracellular vesicles, exosomes and shedding vesicles in regenerative medicine - a new paradigm for tissue repair

Tissue regeneration by stem cells is driven by the paracrine activity of shedding vesicles and exosomes, which deliver specific cargoes to the recipient cells. Proteins, RNA, cytokines and subsequent gene expression, orchestrate the regeneration process by improving the microenvironment to promote cell survival, controlling inflammation, repairing injury and enhancing the healing process. The action of microRNA is widely accepted as an essential driver of the regenerative process through its impact on multiple downstream biological pathways, and its ability to regulate the host immune response. Here, we present an overview of the recent potential uses of exosomes for regenerative medicine and tissue engineering. We also highlight the differences in composition between shedding vesicles and exosomes that depend on the various types of stem cells from which they are derived. The conditions that affect the production of exosomes in different cell types are deliberated. This review also presents the current status of candidate exosomal microRNAs for potential therapeutic use in regenerative medicine, and in applications involving widely studied organs and tissues such as heart, lung, cartilage and bone.

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.