Challenges in identifying the best source of stem cells for cardiac regeneration therapy

Nanotopography promotes cardiogenesis of pluripotent stem cell-derived embryoid bodies through focal adhesion kinase signaling

Controlling the microenvironment surrounding the pluripotent stem cells (PSCs) is a pivotal strategy for regulating cellular differentiation. Surface nanotopography is one of the key factors influencing the lineage-specific differentiation of PSCs. However, much of the underlying mechanism remains unknown. In this study, we focused on the effects of gradient nanotopography on the differentiation of embryoid bodies (EBs). EBs were cultured on three differently sized nanopillar surfaces (Large, 280-360; Medium, 200-280; Small, 120-200 nm) for spontaneous cardiomyocyte differentiation without chemical stimuli. The large nanotopography significantly promoted cardiogenesis, with increased expression of cardiac markers such as α-MHC, cTnT, and cTnI, and redistributed vinculin expression to the contact area. In addition, the small and medium nanotopographies also influenced EB differentiation, affecting both cardiogenesis and hematopoiesis to varying degrees. The phosphorylation of focal adhesion kinase (FAK) decreased in the EBs on the large nanotopography compared to that in the EBs cultured on the flat surface. The gradient nanotopography with 280-360 nm nanopillars is beneficial for the cardiogenesis of EBs in a FAK-dependent manner. This study provides valuable insights into controlling stem cell differentiation through nanotopographical cues, thereby advancing our understanding of the microenvironmental regulation in stem cell-based cardiac tissue engineering.

In situ reprogramming of cardiac fibroblasts into cardiomyocytes in mouse heart with chemicals

Cardiomyocytes are terminal differentiated cells and have limited ability to proliferate or regenerate. Condition like myocardial infarction causes massive death of cardiomyocytes and is the leading cause of death. Previous studies have demonstrated that cardiac fibroblasts can be induced to transdifferentiate into cardiomyocytes in vitro and in vivo by forced expression of cardiac transcription factors and microRNAs. Our previous study have demonstrated that full chemical cocktails could also induce fibroblast to cardiomyocyte transdifferentiation both in vitro and in vivo. With the development of tissue clearing techniques, it is possible to visualize the reprogramming at the whole-organ level. In this study, we investigated the effect of the chemical cocktail CRFVPTM in inducing in situ fibroblast to cardiomyocyte transdifferentiation with two strains of genetic tracing mice, and the reprogramming was observed at whole-heart level with CUBIC tissue clearing technique and 3D imaging. In addition, single-cell RNA sequencing (scRNA-seq) confirmed the generation of cardiomyocytes from cardiac fibroblasts which carries the tracing marker. Our study confirms the use of small molecule cocktails in inducing in situ fibroblast to cardiomyocyte reprogramming at the whole-heart level and proof-of-conceptly providing a new source of naturally incorporated cardiomyocytes to help heart regeneration.

Anti-inflammatory and immunomodulatory effects of mesenchymal stem cell therapy on parasitic drug resistance

INTRODUCTION

The emergence of antiparasitic drug resistance poses a concerning threat to animals and humans. Mesenchymal Stem Cells (MSCs) have been widely used to treat infections in humans, pets, and livestock. Although this is an emerging field of study, the current review outlines possible mechanisms and examines potential synergism in combination therapies and the possible harmful effects of such an approach.

AREAS COVERED

The present study delved into the latest pre-clinical research on utilizing MSCs to treat parasitic infections. As per investigations, the introduction of MSCs to patients grappling with parasitic diseases like schistosomiasis, malaria, cystic echinococcosis, toxoplasmosis, leishmaniasis, and trypanosomiasis has shown a reduction in parasite prevalence. This intervention also alters the levels of both pro- and anti-inflammatory cytokines. Furthermore, the combined administration of MSCs and antiparasitic drugs has demonstrated enhanced efficacy in combating parasites and modulating the immune response.

EXPERT OPINION

Mesenchymal stem cells are a potential solution for addressing parasitic drug resistance. This is mainly because of their remarkable immunomodulatory abilities, which can potentially help combat parasites' resistance to drugs.

Alpha lipoic acid-loaded electrospun fibrous patch films protect heart in acute myocardial infarction mice by inhibiting oxidative stress

Oxidative stress, characterized by excessive accumulation of reactive oxygen species (ROS), is involved in acute myocardial infarction (AMI)-related pathological processes and vascular reperfusion therapy injury. Alpha lipoic acid (LA) exhibits excellent antioxidant properties, however, its application is limited by inherent characteristics, including rapid clearance and extensive volume distribution. In this study, we hypothesized that scavenging cardiac ROS using adequately delivered LA could promote heart repair. Here, we report a new strategy for dynamic-release LA to treat AMI disease. In particular, this involves using poly(lactic-co-glycolic) (PLGA) copolymers as carriers to form a thin film (LA@PLGA) via electrospinning technology to achieve controlled release of LA, which essentially blocking local ROS production in damaged hearts. The drug-loading capacity and capsulation efficiency of this compound film could be regulated by determining the dose proportions of LA and PLGA. The incubation of LA@PLGA showed strong anti-oxidative activity and anti-apoptosis effect in hydrogen peroxide-administered primary cardiomyocytes. Patching LA@PLGA on the infarcted cardiac surfaces of AMI mice dramatically improved heart functions and reduced cardiac fibrosis throughout ventricular remodeling process. Importantly, the attenuation of detrimental pathologies was observed, including oxidative stress, senescence, DNA damage, cytokine-related processes, apoptosis, and ferroptosis. These results suggest that PLGA-carried LA can reduce ROS damage and restore heart function after myocardial damage, demonstrating a great potential for LA drugs in treating AMI disease.

Overexpression of GATA binding protein 4 and myocyte enhancer factor 2C induces differentiation of mesenchymal stem cells into cardiac-like cells

BACKGROUND

Heart diseases are the primary cause of death all over the world. Following myocardial infarction, billions of cells die, resulting in a huge loss of cardiac function. Stem cell-based therapies have appeared as a new area to support heart regeneration. The transcription factors GATA binding protein 4 (GATA-4) and myocyte enhancer factor 2C (MEF2C) are considered prominent factors in the development of the cardiovascular system.

AIM

To explore the potential of GATA-4 and MEF2C for the cardiac differentiation of human umbilical cord mesenchymal stem cells (hUC-MSCs).

METHODS

hUC-MSCs were characterized morphologically and immunologically by the presence of specific markers of MSCs via immunocytochemistry and flow cytometry, and by their potential to differentiate into osteocytes and adipocytes. hUC-MSCs were transfected with GATA-4, MEF2C, and their combination to direct the differentiation. Cardiac differentiation was confirmed by semiquantitative real-time polymerase chain reaction and immunocytochemistry.

RESULTS

hUC-MSCs expressed specific cell surface markers CD105, CD90, CD44, and vimentin but lack the expression of CD45. The transcription factors GATA-4 and MEF2C, and their combination induced differentiation in hUC-MSCs with significant expression of cardiac genes i.e., GATA-4, MEF2C, NK2 homeobox 5 (NKX2.5), MHC, and connexin-43, and cardiac proteins GATA-4, NKX2.5, cardiac troponin T, and connexin-43.

CONCLUSION

Transfection with GATA-4, MEF2C, and their combination effectively induces cardiac differentiation in hUC-MSCs. These genetically modified MSCs could be a promising treatment option for heart diseases in the future.

The Potential Role of Regenerative Medicine on the Future Management of Hypoplastic Left Heart Syndrome

The development and translation of regenerative medicine approaches for the treatment of hypoplastic left heart syndrome (HLHS) provides a promising alternative to the current standard of care. We review the strategies that have been pursued to date and those that hold the greatest promise in moving forward. Significant challenges remain. Continued scientific advances and technological breakthroughs will be required if we are to translate this technology to the clinic and move from palliative to curative treatment.

Efficacy of Stem Cell Therapy in Large Animal Models of Ischemic Cardiomyopathies: A Systematic Review and Meta-Analysis

Stem-cell therapy provides a promising strategy for patients with ischemic heart disease. In recent years, numerous studies related to this therapeutic approach were performed; however, the results were often heterogeneous and contradictory. For this reason, we conducted a systematic review and meta-analysis of trials, reporting the use of stem-cell treatment against acute or chronic ischemic cardiomyopathies in large animal models with regard to Left Ventricular Ejection Fraction (LVEF). The defined research strategy was applied to the PubMed database to identify relevant studies published from January 2011 to July 2021. A random-effect meta-analysis was performed on LVEF mean data at follow-up between control and stem-cell-treated animals. In order to improve the definition of the effect measure and to analyze the factors that could influence the outcomes, a subgroup comparison was conducted. Sixty-six studies (n = 1183 animals) satisfied our inclusion criteria. Ischemia/reperfusion infarction was performed in 37 studies, and chronic occlusion in 29 studies; moreover, 58 studies were on a pig animal model. The meta-analysis showed that cell therapy increased LVEF by 7.41% (95% Confidence Interval 6.23−8.59%; p < 0.001) at follow-up, with significative heterogeneity and high inconsistency (I2 = 82%, p < 0.001). By subgroup comparison, the follow-up after 31−60 days (p = 0.025), the late cell injection (>7 days, p = 0.005) and the route of cellular delivery by surgical treatment (p < 0.001) were significant predictors of LVEF improvement. This meta-analysis showed that stem-cell therapy may improve heart function in large animal models and that the swine specie is confirmed as a relevant animal model in the cardiovascular field. Due to the significative heterogeneity and high inconsistency, future translational studies should be designed to take into account the evidenced predictors to allow for the reduction of the number of animals used.

Nanotechnology in cardiac stem cell therapy: cell modulation, imaging and gene delivery

The wide arena of applications opened by nanotechnology is multidimensional. It is already been proven that its prominence can continuously influence human life. The role of stem cells in curing degenerative diseases is another major area of research. Cardiovascular diseases are one of the major causes of death globally. Nanotechnology-assisted stem cell therapy could be used to tackle the challenges faced in the management of cardiovascular diseases. In spite of the positive indications and proven potential of stem cells to differentiate into cardiomyocytes for cardiac repair and regeneration during myocardial infarction, this therapeutic approach still remains in its infancy due to several factors such as non-specificity of injected cells, insignificant survival rate, and low cell retention. Attempts to improve stem cell therapy using nanoparticles have shown some interest among researchers. This review focuses on the major hurdles associated with cardiac stem cell therapy and the role of nanoparticles to overcome the major challenges in this field, including cell modulation, imaging, tracking and gene delivery.

This review summarizes the potential challenges present in cardiac stem cell therapy and the major role of nanotechnology to overcome these challenges including cell modulation, tracking and imaging of stem cells.

Chronic asthmatic condition modulated the onset of aging in bone marrow mesenchymal stem cells

The emergence of an inflammatory condition such as asthma could affect the therapeutic potential of stem cells. Synopsis of previous documents yielded controversial outcomes, leading to a limitation of stem cell-based therapy in the clinical setting. This study aimed to assess the impact of asthmatic serum on the MSCs aging and dynamic growth in vitro. Rats were divided into control and asthmatic groups randomly. The asthmatic change was induced using OVA sensitization. The asthmatic structural changes are monitored by conventional Haematoxylin-Eosin staining. Thereafter, blood samples were taken and sera provided from each group. In this study, primary bone marrow mesenchymal stem cells were cultured in culture medium supplemented with normal and asthmatic serum for 7 days. The MSCs viability was examined using the MTT assay. The expression of the aging-related gene (β-galactosidase), and stemness-related markers such as Sox2, Kfl-4 and p16^INK4a were analysed by real-time PCR assay. Histological examination revealed chronic inflammatory remodelling which is identical to asthmatic changes. MTT assay showed a reduction of mesenchymal stem cell viability compared to the control group (P < .05). Real-time PCR analysis revealed a down-regulation of stemness-related markers Sox2, Kfl-4 and p16^INK4a coincided with aging changes (β-galactosidase) compared to the control group (P < .05). These data show the detrimental effect of asthmatic condition on bone marrow regenerative potential by accelerating early-stage aging in different stem cells and further progenitor cell depletion. SIGNIFICANCE OF THE STUDY: In such inflammatory conditions as asthma, the therapeutic potential of stem cells may be altered. We demonstrate that serum from asthmatic rats had the potential to reduce the viability of mesenchymal stem cells in vitro. Furthermore, we observed that the expression of the aging-related gene known β-galactosidase was statistically increased in cells co-cultured with asthmatic serum. At the same time, expression of stemness-related markers Sox2, Kfl-4 and p16^INK4a down-regulated. These results support the damaging effect of asthmatic condition on bone marrow regenerative ability by inducing early-stage aging in stem cells and additional progenitor cell reduction.

Current status of cardiac regenerative medicine; An update on point of view to cell therapy application

Cardiovascular diseases (CVDs) are the leading cause of death globally. Because of the economic and social burden of acute myocardial infarction and its chronic consequences in surviving patients, understanding the pathophysiology of myocardial infarction injury is a major priority for cardiovascular research. MI is defined as cardiomyocytes death caused by an ischemic that resulted from the apoptosis, necrosis, necroptosis, and autophagy. The phases of normal repair following MI including inflammatory, proliferation, and maturation. Normal repair is slow and inefficient generally so that other treatments are required. Because of difficulties, outcomes, and backwashes of traditional therapies including coronary artery bypass grafting, balloon angioplasty, heart transplantation, and artificial heart operations, the novel strategy in the treatment of MI, cell therapy, was newly emerged. In cell therapy, a new population of cells has created that substitute with damaged cells. Different types of stem cell and progenitor cells have been shown to improve cardiac function through various mechanisms, including the formation of new myocytes, endothelial cells, and vascular smooth muscle cells. Bone marrow- and/or adipose tissue-derived mesenchymal stem cells, embryonic stem cells, autologous skeletal myoblasts, induced pluripotent stem cells, endothelial progenitor cells, cardiac progenitor cells and cardiac pericytes considered as a source for cell therapy. In this study, we focused on the point of view of the cell sources.

Combination of Cardiac Progenitor Cells From the Right Atrium and Left Ventricle Exhibits Synergistic Paracrine Effects In Vitro

Cardiovascular diseases, such as ischemic heart disease, remain the most common cause of death worldwide. Regenerative medicine with stem cell therapy is a promising tool for cardiac repair. Combination of different cell types has been shown to improve the therapeutic potential, which is thought to be due to synergistic or complimentary reparative effects. We investigated if the combination of cardiac progenitor cells (CPCs) of right atrial appendage (RAA) and left ventricle (LV) that are isolated from the same patient exert synergistic or complimentary paracrine effects for apoptotic cell death and angiogenesis in an in vitro model. Flow cytometry analysis showed that both RAA and LV CPCs expressed the mesenchymal cell markers CD90 and CD105, and were predominantly negative for the hematopoietic cell marker, CD34. Analysis of conditioned media (CM) collected from the CPCs cultured either alone or in combination in serum-deprived hypoxic conditions to simulate ischemia showed marked increase in the level of pro-survival hepatocyte growth factor and pro-angiogenic vascular endothelial growth factor-A in the combined RAA and LV CPC group. Next, to determine the therapeutic potential of CM, AC16 human ventricular cardiomyocytes and human umbilical vein endothelial cells (HUVECs) were treated with CM. Results showed a significant reduction in hypoxia-induced apoptosis of human cardiomyocytes treated with CM collected from combined RAA and LV CPC group. Similarly, matrigel assay showed a significantly increased tube length formed by HUVECs when treated with CM from combined RAA and LV CPC group. Our study provided evidence that the combination of RAA CPCs and LV CPCs may have superior therapeutic effects due to synergistic paracrine effects for cardiac repair. Therefore, in vivo studies are warranted to determine if a combination of different stem cell types have greater therapeutic potential than single-cell therapies.

Reduced graphene oxide facilitates biocompatibility of alginate for cardiac repair

The benefits of combined cell/material therapy appear promising for myocardial infarction treatment. The safety of alginate, along with its excellent biocompatibility and biodegradability, has been extensively investigated for cardiac tissue engineering. Among graphene-based nanomaterials, reduced graphene oxide has been considered as a promising candidate for cardiac treatment due to its unique physicochemical properties. In this study, the reduced graphene oxide incorporation effect within alginate hydrogels was investigated for cardiac repair application. Reduced graphene oxide reinforced alginate properties, resulting in an increase in gel stiffness. The cytocompatibility of the hydrogels prepared with human bone marrow–derived mesenchymal stem cells was assessed by the 3-(4,5dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide) assay. Following reduced graphene oxide addition, alginate-reduced graphene oxide retained significantly higher cell viability compared to that of alginate and cells cultured on tissue culture plates. Acridine orange/propidium iodide staining was also used to identify both viable and necrotic human bone marrow–derived mesenchymal stem cells within the prepared hydrogels. After a 72-h culture, the percentage of viable cells was twice as much as those cultured on either alginate or tissue culture plate, reaching approximately 80%. Quantitative reverse transcription polymerase chain reaction analysis was performed to assess gene expression of neonatal rat cardiac cells encapsulated on hydrogels for TrpT-2, Conx43, and Actn4 after 7 days. The expression of all genes in alginate-reduced graphene oxide increased significantly compared to that in alginate or tissue culture plate. The results obtained confirmed that the presence of reduced graphene oxide, as an electro-active moiety within alginate, could tune the physicochemical properties of this material, providing a desirable electroactive hydrogel for stem cell therapy in patients with ischemic heart disease.

Injectable collagen scaffold promotes swine myocardial infarction recovery by long-term local retention of transplanted human umbilical cord mesenchymal stem cells

Stem cell therapy is an attractive approach for recovery from myocardial infarction (MI) but faces the challenges of rapid diffusion and poor survival after transplantation. Here we developed an injectable collagen scaffold to promote the long-term retention of transplanted cells in chronic MI. Forty-five minipigs underwent left anterior descending artery (LAD) ligation and were equally divided into three groups 2 months later (collagen scaffold loading with human umbilical mesenchymal stem cell (hUMSC) group, hUMSC group, and placebo group (only phosphate-buffered saline (PBS) injection)). Immunofluorescence staining indicated that the retention of transplanted cells was promoted by the collagen scaffold. Echocardiography and cardiac magnetic resonance imaging (CMR) showed much higher left ventricular ejection fraction (LVEF) and lower infarct size percentage in the collagen/hUMSC group than in the hUMSC and placebo groups at 12 months after treatment. There were also higher densities of vWf-, α-sma-, and cTnT-positive cells in the infarct border zone in the collagen/cell group, as revealed by immunohistochemical analysis, suggesting better angiogenesis and more cardiomyocyte survival after MI. Thus, the injectable collagen scaffold was safe and effective on a large animal myocardial model, which is beneficial for constructing a favorable microenvironment for applying stem cells in clinical MI.

Dormant cardiac stem cells: A promising tool in cardiac regeneration

Stem cells represent an old niche with various new potential therapeutics. Besides drug treatment, reperfusion procedures and surgical revascularization, stem cell therapy could be a good option in ischemic cardiac diseases. A study was performed on a small group of cases who died of cardiac arrhythmia secondary to scarring myocardial infarctions. Tissue cardiac samples were taken from these cases (from the anterior and lateral wall of the left ventricle), for microscopy examination, in order to investigate the presence of cardiac stem cells (CSC). Multiple series of histological sections were also performed and examined, along with immunohistochemical analysis (IHC). The cells were identified in close contact with the residual ischemic cardiomyocytes, in the proximity of the myocardial collagenous scar, in old myocardial infarctions. They were activated by hypoxic ischemia and were influenced by the capillary microvascular density and the interstitial micro-environment conditions. In chronic intermittent ischemia they seem to turn themselves from dormant quiescent cells into activated progenitor committed cells.

FoxC1-Induced Vascular Niche Improves Survival and Myocardial Repair of Mesenchymal Stem Cells in Infarcted Hearts

Aims

Forkhead box C1 (FoxC1) is essential for maintaining the hair follicle stem cell niche. The role of FoxC1 in maintaining mesenchymal stem cell (MSC) niches after myocardial infarction (MI) has not been directly determined to date. In this study, we determined to explore the possible roles and mechanisms of FoxC1 on MSC survival and function in the ischemic niche.

Methods and Results

MI model was established in this study, and expression level of FoxC1 was overexpressed or knocked down through efficient delivery of FoxC1 transfection or siFoxC1. Fifteen days later, the animals were allocated randomly to receive phosphate-buffered saline (PBS) injection or MSC transplantation. We identified FoxC1 as a key regulator of maintaining the vascular niche in the infarcted hearts (IHs) by driving proangiogenic and anti-inflammatory cytokines while repressing inflammatory and fibrotic factor expression. This vascular niche improved MSC survival and capacity in the IHs. Importantly, FoxC1 interacted with MSCs and was required for vessel specification and differentiation of engrafted MSCs in the ischemic niches, promoting myocardial repair. Inhibiting FoxC1 abolished these effects.

Conclusion

These results definitively implicate FoxC1 signaling in maintaining ischemic vascular niche, which may be helpful in myocardial repair induced by MSC therapy.

Collagen-Based Microcapsules As Therapeutic Materials for Stem Cell Therapies in Infarcted Myocardium

As cell therapies emerged, it was quickly realized that pro-regenerative cells directly injected into injured tissue struggled within the inflammatory microenvironment. By using microencapsulation, i.e., encapsulating cells within polymeric biomaterials, they are henceforth protected from the harmful extracellular cues, while still being able to receive oxygen and nutrients and release secreted factors. Previous work showed that stem cells encapsulated within a biologically inert material (agarose) were able to significantly improve the function of the infarcted mouse heart. With the aim of using more bioresponsive microcapsules, we sought to develop an enzymatically degradable, type I collagen-based microcapsule for the intramyocardial delivery of bone marrow-derived mesenchymal stromal cells in a murine model of myocardial infarction.

Small molecule 2'-deoxycytidine differentiates human umbilical cord-derived MSCs into cardiac progenitors in vitro and their in vivo xeno-transplantation improves cardiac function

Small molecules are widely used to induce stem cell differentiation. 2'-deoxycytidine (2-DC) belongs to the cytidine family. It stimulates the expression of cardiac-specific genes and proteins, and directs mesenchymal stem cells towards cardiomyogenic differentiation. We aim to investigate the role of 2-DC-treated human umbilical cord mesenchymal stem cells (UC-MSCs) into myogenic lineage and explore their application in regeneration of infarcted myocardium. UC-MSCs were treated with 5, 10, 20, and 40 µM 2-DC following optimization by cytotoxicity analysis. Rat model of myocardial infarction (MI) was induced by ligating left anterior descending coronary artery. Normal, and 2-DC treated UC-MSCs were transplanted in the left ventricular wall immediately after ligation. Echocardiographic measurements were performed to assess cardiac function. Tissue architecture of the myocardium was examined by histological analysis to determine fate of the transplanted cells. MSCs were successfully isolated from human umbilical cord tissue. 2-DC treatment did not produce any significant cytotoxic effect in UC-MSCs at all concentrations. qPCR analysis of treated UC-MSCs showed induction of myogenic differentiation, which is more pronounced at 20 μM concentration. Fluorescently labeled 2-DC-treated UC-MSCs showed significant (**P < 0.01) homing in the infarcted myocardium as compared to normal UC-MSCs. Hearts transplanted with 2-DC-treated UC-MSCs significantly (***P < 0.001) improved the cardiac systolic and diastolic functions and pumping ability as compared to normal UC-MSCs and MI groups. Fibrotic area and left ventricular wall thickness were significantly improved (***P < 0.001) in 2-DC-treated group as compared to normal UC-MSCs. Immunohistochemical staining showed co-localization of fluorescently labeled cells and patches of differentiated myocytes which were stained for cardiac proteins in the infarct zone implying that the treated UC-MSCs regenerated cardiomyocytes. We report for the first time that 2-DC induces cardiac differentiation in UC-MSCs. Transplanted cells differentiated into functional cardiomyocytes and significantly improved cardiac performance. These pre-differentiated cardiac progenitors showed better survival, homing, and distribution in the infarcted zone. 2-DC treated cells not only improved cardiac function, but also restored tissue homeostasis, suggesting a better therapeutic option for the regeneration of cardiac tissue in the clinical setup.

Analyzing Impetus of Regenerative Cellular Therapeutics in Myocardial Infarction

Both vasculature and myocardium in the heart are excessively damaged following myocardial infarction (MI), hence therapeutic strategies for treating MI hearts should concurrently aim for true cardiac repair by introducing new cardiomyocytes to replace lost or injured ones. Of them, mesenchymal stem cells (MSCs) have long been considered a promising candidate for cell-based therapy due to their unspecialized, proliferative differentiation potential to specific cell lineage and, most importantly, their capacity of secreting beneficial paracrine factors which further promote neovascularization, angiogenesis, and cell survival. As a consequence, the differentiated MSCs could multiply and replace the damaged tissues to and turn into tissue- or organ-specific cells with specialized functions. These cells are also known to release potent anti-fibrotic factors including matrix metalloproteinases, which inhibit the proliferation of cardiac fibroblasts, thereby attenuating fibrosis. To achieve the highest possible therapeutic efficacy of stem cells, the other interventions, including hydrogels, electrical stimulations, or platelet-derived biomaterials, have been supplemented, which have resulted in a narrow to broad range of outcomes. Therefore, this article comprehensively analyzed the progress made in stem cells and combinatorial therapies to rescue infarcted myocardium.

Systemic and local delivery of mesenchymal stem cells for heart renovation: Challenges and innovations

In the beginning stage of heart disease, the blockage of blood flow frequently occurs due to the persistent damage and even death of myocardium. Cicatricial tissue developed after the death of myocardium can affect heart function, which ultimately leads to heart failure. In recent years, several studies carried out about the use of stem cells such as embryonic, pluripotent, cardiac and bone marrow-derived stem cells as well as myoblasts to repair injured myocardium. Current studies focus more on finding appropriate measures to enhance cell homing and survival in order to increase paracrine function. Until now, there is no universal delivery route for mesenchymal stem cells (MSCs) for different diseases. In this review, we summarize the advantages and challenges of the systemic and local pathways of MSC delivery. In addition, we also describe some advanced measures of cell delivery to improve the efficiency of transplantation. The combination of cells and therapeutic substances could be the most reliable method, which allows donor cells to deliver sufficient amounts of paracrine factors and provide long-lasting effects. The cardiac support devices or tissue engineering techniques have the potential to facilitate the controlled release of stem cells on local tissue for a sustained period. A novel promising epicardial drug delivery system is highlighted here, which not only provides MSCs with a favorable environment to promote retention but also increases the contact area and a number of cells recruited in the heart muscle.

Cardiac Nestin+ Mesenchymal Stromal Cells Enhance Healing of Ischemic Heart through Periostin-Mediated M2 Macrophage Polarization

Mesenchymal stromal cells (MSCs) show potential for treating cardiovascular diseases, but their therapeutic efficacy exhibits significant heterogeneity depending on the tissue of origin. This study sought to identify an optimal source of MSCs for cardiovascular disease therapy. We demonstrated that Nestin was a suitable marker for cardiac MSCs (Nes⁺cMSCs), which were identified by their self-renewal ability, tri-lineage differentiation potential, and expression of MSC markers. Furthermore, compared with bone marrow-derived MSCs (Nes⁺bmMSCs) or saline-treated myocardial infarction (MI) controls, intramyocardial injection of Nes⁺cMSCs significantly improved cardiac function and decreased infarct size after acute MI (AMI) through paracrine actions, rather than transdifferentiation into cardiac cells in infarcted heart. We further revealed that Nes⁺cMSC treatment notably reduced pan-macrophage infiltration while inducing macrophages toward an anti-inflammatory M2 phenotype in ischemic myocardium. Interestingly, Periostin, which was highly expressed in Nes⁺cMSCs, could promote the polarization of M2-subtype macrophages, and knockdown or neutralization of Periostin remarkably reduced the therapeutic effects of Nes⁺cMSCs by decreasing M2 macrophages at lesion sites. Thus, the present work systemically shows that Nes⁺cMSCs have greater efficacy than do Nes⁺bmMSCs for cardiac healing after AMI, and that this occurs at least partly through Periostin-mediated M2 macrophage polarization.

Wnt Signaling: The double-edged sword diminishing the potential of stem cell therapy in congenital heart disease

Stem cell therapy using bone marrow derived or mesenchymal stem cells has become a popular option for cardiovascular disease treatment, however the administration of embryonic stem cells has been mostly experimental. Remarkably, most of these ongoing clinical trials involve adult patients, but little is known regarding the safety and efficacy of stem cell therapy in newborns and children battling congenital heart diseases. Furthermore, cell delivery methods involve the administration of stem cells without pre-differentiation, and without consideration for the consequent process of cardiac development. Interestingly, in-vitro studies have demonstrated that the differentiation of embryonic stem cells into cardiomyocytes imitates the stages of cardiogenesis. Wnt signaling plays a profound role during the earliest stages of cardiogenesis and cardiac differentiation. In fact inappropriate Wnt signaling is associated with numerous cardiac disorders especially congenital heart disease. Furthermore, cell-extracellular matrix interactions were shown to be critical for stem cell differentiation and adequate cardiogenesis. Since extracellular matrix molecules are fundamental for maintenance and repair during heart disease and congenital heart disease, they may offer a novel approach for therapy. Herein we aim to review the critical role of Wnt signaling, as well as the profound importance of cell extracellular matrix interaction, during cardiogenesis. Both of these processes are crucial for precise stem cell differentiation into cardiomyocytes and developing efficacious regenerative therapy for congenital heart disease.

Aging: A cell source limiting factor in tissue engineering

Tissue engineering has yet to reach its ideal goal, i.e. creating profitable off-the-shelf tissues and organs, designing scaffolds and three-dimensional tissue architectures that can maintain the blood supply, proper biomaterial selection, and identifying the most efficient cell source for use in cell therapy and tissue engineering. These are still the major challenges in this field. Regarding the identification of the most appropriate cell source, aging as a factor that affects both somatic and stem cells and limits their function and applications is a preventable and, at least to some extents, a reversible phenomenon. Here, we reviewed different stem cell types, namely embryonic stem cells, adult stem cells, induced pluripotent stem cells, and genetically modified stem cells, as well as their sources, i.e. autologous, allogeneic, and xenogeneic sources. Afterward, we approached aging by discussing the functional decline of aged stem cells and different intrinsic and extrinsic factors that are involved in stem cell aging including replicative senescence and Hayflick limit, autophagy, epigenetic changes, miRNAs, mTOR and AMPK pathways, and the role of mitochondria in stem cell senescence. Finally, various interventions for rejuvenation and geroprotection of stem cells are discussed. These interventions can be applied in cell therapy and tissue engineering methods to conquer aging as a limiting factor, both in original cell source and in the in vitro proliferated cells.

Protective mechanism of artemisinin on rat bone marrow-derived mesenchymal stem cells against apoptosis induced by hydrogen peroxide via activation of c-Raf-Erk1/2-p90rsk-CREB pathway

Background

Bone marrow-derived mesenchymal stem cell (BMSC) transplantation is one of the new therapeutic strategies for treating ischemic brain and heart tissues. However, the poor survival rate of transplanted BMSCs in ischemic tissue, due to high levels of reactive oxygen species (ROS), limits the therapeutic efficacy of this approach. Considering that BMSC survival may greatly enhance the effectiveness of transplantation therapy, development of effective therapeutics capable of mitigating oxidative stress-induced BMSC apoptosis is an important unmet clinical need.

Methods

BMSCs were isolated from the 4-week-old male Sprague Dawley rats by whole bone marrow adherent culturing, and the characteristics were verified by morphology, immunophenotype, adipogenic, and osteogenic differentiation potential. BMSCs were pretreated with artemisinin, and H₂O₂ was used to induce apoptosis. Cell viability was detected by MTT, FACS, LDH, and Hoechst 33342 staining assays. Mitochondrial membrane potential (ΔΨm) was measured by JC-1 assay. The apoptosis was analyzed by Annexin V-FITC/PI and Caspase 3 Activity Assay kits. ROS level was evaluated by using CellROX® Deep Red Reagent. SOD, CAT, and GPx enzymatic activities were assessed separately using Cu/Zn-SOD and Mn-SOD Assay Kit with WST-8, Catalase Assay Kit, and Total Glutathione Peroxidase Assay Kit. The effects of artemisinin on protein expression of BMSCs including p-Erk1/2, t-Erk1/2, p-c-Raf, p-p90^rsk, p-CREB, BCL-2, Bax, p-Akt, t-Akt, β-actin, and GAPDH were measured by western blotting.

Results

We characterized for the first time the protective effect of artemisinin, an anti-malaria drug, using oxidative stress-induced apoptosis in vitro, in rat BMSC cultures. We found that artemisinin, at clinically relevant concentrations, improved BMSC survival by reduction of ROS production, increase of antioxidant enzyme activities including SOD, CAT, and GPx, in correlation with decreased Caspase 3 activation, lactate dehydrogenase (LDH) release and apoptosis, all induced by H₂O₂. Artemisinin significantly increased extracellular-signal-regulated kinase 1/2 (Erk1/2) phosphorylation, in a concentration- and time-dependent manner. PD98059, the specific inhibitor of the Erk1/2 pathway, blocked Erk1/2 phosphorylation and artemisinin protection. Similarly, decreased expression of Erk1/2 by siRNA attenuated the protective effect of artemisinin. Additionally, when the upstream activator KRAS was knocked down by siRNA, the protective effect of artemisinin was also blocked. These data strongly indicated the involvement of the Erk1/2 pathway. Consistent with this hypothesis, artemisinin increased the phosphorylation of Erk1/2 upstream kinases proto-oncogene c-RAF serine/threonine-protein kinase (c-Raf) and of Erk1/2 downstream targets p90 ribosomal s6 kinase (p90^rsk) and cAMP response element binding protein (CREB). In addition, we found that the expression of anti-apoptotic protein B cell lymphoma 2 protein (BcL-2) was also upregulated by artemisinin.

Conclusion

These studies demonstrate the proof of concept of artemisinin therapeutic potential to improve survival in vitro of BMSCs exposed to ROS-induced apoptosis and suggest that artemisinin-mediated protection occurs via the activation of c-Raf-Erk1/2-p90^rsk-CREB signaling pathway.

Optimization of Timing and Times for Administration of Atorvastatin-Pretreated Mesenchymal Stem Cells in a Preclinical Model of Acute Myocardial Infarction

Our previous studies showed that the combination of atorvastatin (ATV) and single injection of ATV-pretreated mesenchymal stem cells (MSCs) (ATV -MSCs) at 1 week post-acute myocardial infarction (AMI) promoted MSC recruitment and survival. This study aimed to investigate whether the combinatorial therapy of intensive ATV with multiple injections of ATV -MSCs has greater efficacy at different stages to better define the optimal strategy for MSC therapy in AMI. In order to determine the optimal time window for MSC treatment, we first assessed stromal cell-derived factor-1 (SDF-1) dynamic expression and inflammation. Next, we compared MSC recruitment and differentiation, cardiac function, infarct size, and angiogenesis among animal groups with single, dual, and triple injections of ATV -MSCs at early (Early1, Early2, Early3), mid-term (Mid1, Mid2, Mid3), and late (Late1, Late2, Late3) stages. Compared with AMI control, intensive ATV significantly augmented SDF-1 expression 1.5∼2.6-fold in peri-infarcted region with inhibited inflammation. ATV -MSCs implantation with ATV administration further enhanced MSC recruitment rate by 3.9%∼24.0%, improved left ventricular ejection fraction (LVEF) by 2.0%∼16.2%, and reduced infarct size in all groups 6 weeks post-AMI with most prominent improvement in mid groups and still effective in late groups. Mechanistically, ATV -MSCs remarkably suppressed inflammation and apoptosis while increasing angiogenesis. Furthermore, triple injections of ATV -MSCs were much more effective than single administration during early and mid-term stages of AMI with the best effects in Mid3 group. We conclude that the optimal strategy is multiple injections of ATV -MSCs combined with intensive ATV administration at mid-term stage of AMI. The translational potential of this strategy is clinically promising. Stem Cells Translational Medicine 2019;8:1068-1083.

Umbilical cord-derived mesenchymal stromal cells in cardiovascular disease: review of preclinical and clinical data

The human umbilical cord has recently emerged as an attractive potential source of mesenchymal stromal cells (MSCs) to be adopted for use in regenerative medicine. Umbilical cord MSCs (UC-MSCs) not only share the same features of all MSCs such as multi-lineage differentiation, paracrine functions and immunomodulatory properties, they also have additional advantages, such as no need for bone marrow aspiration and higher self-renewal capacities. They can be isolated from various compartments of the umbilical cord (UC) and can be used for autologous or allogeneic purposes. In the past decade, they have been adopted in cardiovascular disease and have shown promising results mainly due to their pro-angiogenic and anti-inflammatory properties. This review offers an overview of the biological properties of UC-MSCs describing available pre-clinical and clinical data with respect to their potential therapeutic use in cardiovascular regeneration, with current challenges and future directions discussed.

Development of a bio-MEMS device for electrical and mechanical conditioning and characterization of cell sheets for myocardial repair

Here we propose a bio-MEMS device designed to evaluate contractile force and conduction velocity of cell sheets in response to mechanical and electrical stimulation of the cell source as it grows to form a cellular sheet. Moreover, the design allows for the incorporation of patient-specific data and cell sources. An optimized device would allow cell sheets to be cultured, characterized, and conditioned to be compatible with a specific patient's cardiac environment in vitro, before implantation. This design draws upon existing methods in the literature but makes an important advance by combining the mechanical and electrical stimulation into a single system for optimized cell sheet growth. The device has been designed to achieve cellular alignment, electrical stimulation, mechanical stimulation, conduction velocity readout, contraction force readout, and eventually cell sheet release. The platform is a set of comb electrical contacts consisting of three-dimensional walls made of polydimethylsiloxane and coated with electrically conductive metals on the tops of the walls. Not only do the walls serve as a method for stimulating cells that are attached to the top, but their geometry is tailored such that they are flexible enough to be bent by the cells and used to measure force. The platform can be stretched via a linear actuator setup, allowing for simultaneous electrical and mechanical stimulation that can be derived from patient-specific clinical data.

Mesenchymal Stem Cell Therapy for Doxorubicin-Induced Cardiomyopathy: Potential Mechanisms, Governing Factors, and Implications of the Heart Stem Cell Debate

Over the past decades, researchers have reported several mechanisms for doxorubicin (DOX)-induced cardiomyopathy, including oxidative stress, inflammation, and apoptosis. Another mechanism that has been suggested is that DOX interferes with the cell cycle and induces oxidative stress in C-kit+ cells (commonly known as cardiac progenitor cells), reducing their regenerative capacity. Cardiac regeneration through enhancing the regenerative capacity of these cells or administration of other stem cells types has been the axis of several studies over the past 20 years. Several experiments revealed that local or systemic injections with mesenchymal stem cells (MSCs) were associated with significantly improved cardiac function, ameliorated inflammatory response, and reduced myocardial fibrosis. They also showed that several factors can affect the outcome of MSC treatment for DOX cardiomyopathy, including the MSC type, dose, route, and timing of administration. However, there is growing evidence that the C-kit+ cells do not have a cardiac regenerative potential in the adult mammalian heart. Similarly, the protective mechanisms of MSCs against DOX-induced cardiomyopathy are not likely to include direct differentiation into cardiomyocytes and probably occur through paracrine secretion, antioxidant and anti-inflammatory effects. Better understanding of the involved mechanisms and the factors governing the outcomes of MSCs therapy are essential before moving to clinical application in patients with DOX-induced cardiomyopathy.

Therapeutic potential of menstrual blood-derived endometrial stem cells in cardiac diseases

Despite significant developments in medical and surgical strategies, cardiac diseases remain the leading causes of morbidity and mortality worldwide. Numerous studies involving preclinical and clinical trials have confirmed that stem cell transplantation can help improve cardiac function and regenerate damaged cardiac tissue, and stem cells isolated from bone marrow, heart tissue, adipose tissue and umbilical cord are the primary candidates for transplantation. During the past decade, menstrual blood-derived endometrial stem cells (MenSCs) have gradually become a promising alternative for stem cell-based therapy due to their comprehensive advantages, which include their ability to be periodically and non-invasively collected, their abundant source material, their ability to be regularly donated, their superior proliferative capacity and their ability to be used for autologous transplantation. MenSCs have shown positive therapeutic potential for the treatment of various diseases. Therefore, aside from a brief introduction of the biological characteristics of MenSCs, this review focuses on the progress being made in evaluating the functional improvement of damaged cardiac tissue after MenSC transplantation through preclinical and clinical studies. Based on published reports, we conclude that the paracrine effect, transdifferentiation and immunomodulation by MenSC promote both regeneration of damaged myocardium and improvement of cardiac function.

Safe and Effective Delivery of Antitumor Drug Using Mesenchymal Stem Cells Impregnated with Submicron Carriers

An important area in modern malignant tumor therapy is the optimization of antitumor drugs pharmacokinetics. The use of some antitumor drugs is limited in clinical practice due to their high toxicity. Therefore, the strategy for optimizing the drug pharmacokinetics focuses on the generation of high local concentrations of these drugs in the tumor area with minimal systemic and tissue-specific toxicity. This can be achieved by encapsulation of highly toxic antitumor drug (vincristine (VCR) that is 20-50 times more toxic than widely used the antitumor drug doxorubicin) into nano- and microcarriers with their further association into therapeutically relevant cells that possess the ability to migrate to sites of tumor. Here, we fundamentally examine the effect of drug carrier size on the behavior of human mesenchymal stem cells (hMSCs), including internalization efficiency, cytotoxicity, cell movement, to optimize the conditions for the development of carrier-hMSCs drug delivery platform. Using the malignant tumors derived from patients, we evaluated the capability of hMSCs associated with VCR-loaded carriers to target tumors using a three-dimensional spheroid model in collagen gel. Compared to free VCR, the developed hMSC-based drug delivery platform showed enhanced antitumor activity regarding those tumors that express CXCL12 (stromal cell-derived factor-1 (SDF-1)) gene, inducing directed migration of hMSCs via CXCL12 (SDF-1)/CXCR4 pathway. These results show that the combination of encapsulated antitumor drugs and hMSCs, which possess the properties of active migration into tumors, is therapeutically beneficial and demonstrated high efficiency and low systematic toxicity, revealing novel strategies for chemotherapy in the future.

STAT3 Phosphorylation Mediating DMSO's Function on Fetal Cardiomyocyte Proliferation with Developmental Changes

Endogenous cardiac regeneration has been focused for decades as a potential therapy for heart diseases with cell loss, and dimethyl sulfoxide (DMSO) has been proposed as a treatment for many diseases. In this study, we aimed to investigate the function of DMSO on fetal cardiomyocyte proliferation. By tracing BrdU⁺/α actinin⁺ cells or Ki67⁺/α actinin⁺ cells with immunohistochemical staining, we found that DMSO remarkably promoted fetal cardiomyocytes proliferation, and at the late developmental stage (LDS), such effects were more efficient than that at early developmental stage (EDS). Western blot data revealed a significant increase in STAT3 phosphorylation under DMSO treatments at LDS, while not at EDS. Consistently, STAT3 phosphorylation blocker STA21 could greatly reverse DMSO's function at LDS whereas hardly at EDS. Moreover, hearts at the EDS had less total STAT3 protein, but relatively much higher level of phosphorylated STAT3. This suggests that DMSO promote fetal cardiomyocytes proliferation, and STAT3 phosphorylation play a pivotal role in DMSO's function. With maturation, DMSO exerted a better ability to favor cardiomyocyte proliferation depending on STAT3 phosphorylation. Therefore, DMSO could serve as an effective, economic, and safe therapy for heart diseases with cell loss.

The Challenges of Stem Cell Therapy in Myocardial Infarction and Heart Failure and the Potential Strategies to Improve the Outcomes

Cardiovascular disease remains the single highest global cause of death and a significant financial burden on the healthcare system. Despite the advances in medical treatments, the prevalence and mortality for heart failure remain unacceptably high. New approaches are urgently needed to reduce this burden and improve patient outcomes and quality of life. One such promising approach is stem cell therapy, including embryonic stem cells, bone marrow derived stem cells, induced pluripotent stem cells and mesenchymal stem cells. However, the cardiac microenvironment following myocardial infarction poses huge challenges with inflammation, adequate retention, engraftment and functional incorporation all crucial concerns. The lack of cardiac regeneration, cell viability and functional improvement has hindered the success of stem cell therapy in clinical settings. The use of biomaterial scaffolds in conjunction with stem cells has recently been shown to enhance the outcome of stem cell therapy for heart failure and myocardial infarction. This review outlines some of the current challenges in the treatment of heart failure and acute myocardial infarction through improving stem cell therapeutic strategies, as well as the prospect of suitable biomaterial scaffolds to enhance their efficacy and improve patient clinical outcomes.

Exosomes: Basic Biology and Technological Advancements Suggesting Their Potential as Ischemic Heart Disease Therapeutics

Exosomes are small nano-sized vesicles that deliver biologically active RNA molecules and proteins to recipient cells through binding, fusion or endocytosis. There is emerging evidence that endogenous exosomes released by cardiovascular cells and progenitor cells impact cell survival and proliferation, thus regulating angiogenesis, cardiac protection and repair. These cardioprotective and regenerative traits have the potential to translate in to novel therapeutic options for post-ischaemic cardiac regeneration, thus potentially delaying the progression to ischaemic heart failure. Cellular stressors influence exosomes' secretion and the molecular composition of the exosome cargo, thus impacting on the above processes. Evidences are emerging that loading of proteins and RNAs in the exosomes cargos can be manipulated. Similarly, manipulation of exosomes surface proteins' expression to target exosomes to specific cells and tissues is doable. In addition, nature-inspired synthetic exosomes can be assembled to deliver specific clues to the recipient cells, including proliferative and differentiation stimuli, or shed paracrine signals enabling to reconstructing the heart homeostatic micro-environment. This review will describe exosome biogenesis and emerging evidence of exosome-mediated regenerative cell-to-cell communications and will conclude discussing possibilities of using exosomes to treat ischemic heart disease.

Body builder: from synthetic cells to engineered tissues

It is estimated that 18 Americans die every day waiting for an organ donation. And even if a patient receives the organ that s/he needs, there is still >10% chance that the new organ will not work. The field of tissue engineering and regenerative medicine aims to actively use a patient's own cells, plus biomaterials and factors, to grow specific tissues for replacement or to restore normal functions of that organ, which would eliminate the need for donors and the risk of alloimmune rejection. In this review, we summarized recent advances in fabricating synthetic cells, with a specific focus on their application to cardiac regenerative medicine and tissue engineering. At the end, we pointed to challenges and future directions for the field.

The pulmonary microvasculature entraps induced vascular progenitor cells (iVPCs) systemically delivered after cardiac ischemia-reperfusion injury: Indication for preservation of heart function via paracrine effects beyond engraftment

OBJECTIVE

Stem cell-based regenerative therapies have been intensively studied with the aim to define an ideal cell type for the treatment of myocardial infarction. We tested systemically delivered, platelet-targeted induced vascular progenitor cells (iVPCs) to study their potential to salvage damaged myocardium after ischemia-reperfusion injury.

METHODS

Using a mouse model of ischemia-reperfusion injury, we tested the potential of platelet-targeted iVPCs (1 × 10⁶ targ-iVPCs) compared to non-targ-iVPCs and a saline control. Bioluminescence imaging, echocardiography, and histological analyses were performed.

RESULTS

Four weeks after ischemia-reperfusion injury, systemic delivery of targ-iVPCs led to reduced fibrosis and infarct size (PBS: 25.7 ± 3.9 vs targ-iVPC: 18.4 ± 6.6 vs non-targ-iVPC: 25.1 ± 3.7%I/LV, P < 0.05), increased neovascularization, and restored cardiac function (PBS: 44.0 ± 4.2 vs targ-iVPC: 54.3 ± 4.5 vs non-targ-iVPC: 46.4 ± 3.8%EF, P < 0.01). Cell tracking experiments revealed entrapment of intravenously injected iVPCs in the pulmonary microvasculature in both cell-treated groups.

CONCLUSIONS

Systemic delivery of iVPCs after cardiac ischemia-reperfusion injury is limited by pulmonary entrapment of the cells. Nevertheless, targ-iVPCs reduced infarct size, fibrosis, increased neovascularization, and most importantly retained cardiac function. These findings contribute to the mechanistic discussion of cell-based therapy and ultimately identify activated platelet-targeted iVPCs as candidates for cell therapy and also describe cell therapy benefits without the necessity of engrafting.

Enhancement Strategies for Cardiac Regenerative Cell Therapy: Focus on Adult Stem Cells

The idiom heart of the matter refers to the focal point within a topic and, with regard to health and longevity, the heart is truly pivotal for quality of life. Societal trends worldwide continue toward increased percent body fat and decreased physical activity with coincident increases in chronic diseases including cardiovascular disease as the top global cause of death along with insulin resistance, accelerated aging, cancer. Although long-term survival rates for cardiovascular disease patients are grim, intense research efforts continue to improve both prevention and treatment options. Pharmacological interventions remain the predominant interventional strategy for mitigating progression and managing symptoms, but cellular therapies have the potential to cure or even mediate remission of cardiovascular disease. Adult stem cells are the most studied cellular therapy in both preclinical and clinical investigation. This review will focus on the advanced therapeutic strategies to augment products and methods of delivery, which many think heralds the future of clinical investigations. Advanced preclinical strategies using adult stem cells are examined to promote synergism between preclinical and clinical research, streamline implementation, and improve this imminent matter of the heart.

New therapies for acute myocardial infarction: current state of research and future promise

Progress has been made into research on new therapies, mechanical and pharmacological approaches and repair/regenerative cellular therapy to treat irreversible cardiovascular pathologies, such as acute myocardial infarction. Research into cellular therapies is exploring the use of new cellular types. Although the therapeutic effects of cell therapy remain modest, results from clinical trials are encouraging. To expand this improvement, advances are being made that involve the paracrine function of stem cells, the use of growth factors, miRNA and new biomaterials. In the near future, these therapies should become part of routine clinical practice.

Migration of mesenchymal stem cells to tumor xenograft models and in vitro drug delivery by doxorubicin

Mesenchymal stem cells (MSCs) show therapeutic effects in various types of diseases. MSCs have been shown to migrate towards inflamed or cancerous tissues, and visualized after sacrificing the animal. MSCs are able to deliver drugs to target cells, and are an ideal candidate for cancer therapy. The purpose of this study was to track the migration of MSCs in tumor-bearing mice; MSCs were also used as drug delivery vehicles. Human breast cancer cells (MDA-MB-231) and anaplastic thyroid cancer cells (CAL62) were transduced with lentiviral particles, to express the Renilla luciferase and mCherry (mCherry-Rluc) reporter genes. Human bone marrow-derived MSCs were transduced with lentiviral particles, to express the firefly luciferase and enhanced green fluorescence protein (Fluc2-eGFP) reporter genes (MSC/Fluc). Luciferase activity of the transduced cells was measured by bioluminescence imaging (BLI). Further in vitro migration assays were performed to confirm cancer cells conditioned medium dependent MSC and doxorubicin (DOX) treated MSC migration. MSCs were loaded with DOX, and their therapeutic effects against the cancer cells were studied in vitro. In vivo MSC/Fluc migration in mice having thyroid or breast cancer xenografts was evaluated after systemic injection. Rluc activity of CAL62/Rluc (R2=0.911), MDA-MB-231/Rluc (R2=0.934) cells and Fluc activity of MSC/Fluc (R2=0.91) cells increased with increasing cell numbers, as seen by BLI. eGFP expression of MSC/Fluc was confirmed by confocal microscopy. Similar migration potential was observed between MSC/Fluc and naïve MSCs in migration assay. DOX treated MSCs migration was not decreased compared than MSCs. Migration of the systemically injected MSC/Fluc cells into tumor xenografts (thyroid and breast cancer) was visualized in animal models (p<0.05) and confirmed by ex vivo (p<0.05) BLI. Additionally, MSCs delivered DOX to CAL62/Rluc and MDA-MB-231/Rluc cells, thereby decreasing their Rluc activities. In this study, we confirmed the migration of MSCs to tumor sites in cancer xenograft models using both in vivo and ex vivo BLI imaging. DOX-pretreated MSCs showed enhanced cytotoxic effects. Therefore, this noninvasive reporter gene (Fluc2)-based BLI may be useful for visualizing in vivo tracking of MSCs, which can be used as a drug delivery vehicle for cancer therapy.

Therapeutic Use of Stem Cells for Myocardial Infarction

Myocardial infarction is a leading cause of morbidity and mortality worldwide. Although medical and surgical treatments can significantly improve patient outcomes, no treatment currently available is able to generate new contractile tissue or reverse ischemic myocardium. Driven by the recent/novel understanding that regenerative processes do exist in the myocardium—tissue previously thought not to possess regenerative properties—the use of stem cells has emerged as a promising therapeutic approach with high expectations. The literature describes the use of cells from various sources, categorizing them as either embryonic, induced pluripotent, or adult/tissue stem cells (mesenchymal, hematopoietic, skeletal myoblasts, cardiac stem cells). Many publications show the successful use of these cells to regenerate damaged myocardium in both animal and human models; however, more studies are needed to directly compare cells of various origins in efforts to draw conclusions on the ideal source. Although numerous challenges exist in this developing area of research and clinical practice, prospects are encouraging. The following aims to provide a concise review outlining the different types of stem cells used in patients after myocardial infarction.

Mechanical and Chemical Predifferentiation of Mesenchymal Stem Cells Into Cardiomyocytes and Their Effectiveness on Acute Myocardial Infarction

Myocardial infarction is one of the leading causes of death all over the world. Mesenchymal stem cells (MSCs) transplantation has shown a promising potential to recovery of ischemic heart disease due to their capability in differentiating into cardiac cells. However, various investigations have been performed to optimize the efficacy of cardiac cell therapy in recent years. Here, we sought to interrogate the effect of autologous transplantation of undifferentiated and predifferentiated adipose and bone marrow-derived MSCs in a rabbit model of myocardial infarction and also to investigate whether cardiac function could be improved by mechanically induced MSCs via equiaxial cyclic strain. The two sources of MSCs were induced toward cardiomyocyte phenotype using mechanical loading and chemical factors and thereafter injected into the infarcted myocardium of 35 rabbits. Echocardiography and histopathology studies were used to evaluate cardiac function after 2 months. The results demonstrated significant scar size reduction and greater recovery of left ventricle ejection fraction after transplantation of predifferentiated cells, though the differences were not significant when comparing mechanically with chemically predifferentiated MSCs. Thus, although there was no significant improvement in infarcted myocardium between chemically and mechanically predifferentiated MSCs, mechanically induced cells are more preferred due to lack of any chemical intervention and cost reasonableness in their preparation method. Outcomes of this study may be useful for developing future therapeutic strategies, however long-term assessments are still required to further examine their effectiveness.

Recent Advances in Treatment of Coronary Artery Disease: Role of Science and Technology

Coronary artery disease (CAD) is one of the most common causes of death worldwide. In the last decade, significant advancements in CAD treatment have been made. The existing treatment is medical, surgical or a combination of both depending on the extent, severity and clinical presentation of CAD. The collaboration between different science disciplines such as biotechnology and tissue engineering has led to the development of novel therapeutic strategies such as stem cells, nanotechnology, robotic surgery and other advancements (3-D printing and drugs). These treatment modalities show promising effects in managing CAD and associated conditions. Research on stem cells focuses on studying the potential for cardiac regeneration, while nanotechnology research investigates nano-drug delivery and percutaneous coronary interventions including stent modifications and coatings. This article aims to provide an update on the literature (in vitro, translational, animal and clinical) related to these novel strategies and to elucidate the rationale behind their potential treatment of CAD. Through the extensive and continued efforts of researchers and clinicians worldwide, these novel strategies hold the promise to be effective alternatives to existing treatment modalities.

[Stem cells: searching predisposition to cardiac commitment by surface markers expression]

It is well-known that cardiovascular diseases are the leading cause of death worldwide, and represent an important economic burden to health systems. In an attempt to solve this problem, stem cell therapy has emerged as a therapeutic option. Within the last 20 years, a great variety of stem cells have been used in different myocardial infarction models. Up until now, the use of cardiac stem cells (CSCs) has seemed to be the best option, but the inaccessibility and scarcity of these cells make their use unreliable. Additionally, there is a high risk as they have to be obtained directly from the heart of the patient. Unlike CSCs, adult stem cells originating from bone marrow or adipose tissue, among others, appear to be an attractive option due to their easier accessibility and abundance, but particularly due to the probable existence of cardiac progenitors among their different sub-populations. In this review an analysis is made of the surface markers present in CSCs compared with other adult stem cells. This suggested the pre-existence of cells sharing specific surface markers with CSCs, a predictable immunophenotype present in some cells, although in low proportions, and with a potential of cardiac differentiation that could be similar to CSCs, thus increasing their therapeutic value. This study highlights new perspectives regarding MSCs that would enable some of these sub-populations to be differentiated at cardiac tissue level.

Role of Extracellular Matrix in Cardiac Cellular Therapies

The extracellular matrix (ECM) is an essential regulator of homeostasis at the cellular, tissue, and organ level. It is now very well known that ECM dynamic remodeling is indispensable not only for normal growth and development but also recovery from tissue injuries. Indeed, abnormal remodeling of the ECM plays a major role in many pathophysiological processes and contributes to many different pathologies including cardiovascular disorders. Recently, cellular therapies have emerged as a potential therapeutic strategy for restoration of lost cardiomyocytes or their rejuvenation after cardiac damage and injuries. Harnessing the biological properties of ECM could be a viable strategy to enhance the therapeutic effects of cellular therapies by improving the engraftment, integration, survival, and functional adaptation of newly transplanted cells in many different platforms. Conversely, transplanted cells could restore the functionality and original composition of damaged ECM by secreting and depositing new ECM or stimulating normal ECM production by cardiac tissue native cells. Although the ultimate role of cell therapy in treatment of cardiac disorders is still a matter of great debate, the potential utility of ECM in improving the therapeutic effect of transplanted cells and vice versa the potential role of cell therapy as a means to restore the structure and functionality of damaged ECM should be carefully considered in implementation of future clinical cardiovascular cell therapy trials.

Mdivi-1 Protects Human W8B2+ Cardiac Stem Cells from Oxidative Stress and Simulated Ischemia-Reperfusion Injury

Cardiac stem cell (CSC) therapy is a promising approach to treat ischemic heart disease. However, the poor survival of transplanted stem cells in the ischemic myocardium has been a major impediment in achieving an effective cell-based therapy against myocardial infarction. Inhibiting mitochondrial fission has been shown to promote survival of several cell types. However, the role of mitochondrial morphology in survival of human CSC remains unknown. In this study, we investigated whether mitochondrial division inhibitor-1 (Mdivi-1), an inhibitor of mitochondrial fission protein dynamin-related protein-1 (Drp1), can improve survival of a novel population of human W8B2⁺ CSCs in hydrogen peroxide (H₂O₂)-induced oxidative stress and simulated ischemia-reperfusion injury models. Mdivi-1 significantly reduced H₂O₂-induced cell death in a dose-dependent manner. This cytoprotective effect was accompanied by an increased proportion of cells with tubular mitochondria, but independent of mitochondrial membrane potential recovery and reduction of mitochondrial superoxide production. In simulated ischemia-reperfusion injury model, Mdivi-1 given as a pretreatment or throughout ischemia-reperfusion injury significantly reduced cell death. However, the cytoprotective effect of Mdivi-1 was not observed when given at reperfusion. Moreover, the cytoprotective effect of Mdivi-1 in the simulated ischemia-reperfusion injury model was not accompanied by changes in mitochondrial morphology, mitochondrial membrane potential, or mitochondrial reactive oxygen species production. Mdivi-1 also did not affect mitochondrial bioenergetics of intact W8B2⁺ CSCs. Taken together, these experiments demonstrated that Mdivi-1 treatment of human W8B2⁺ CSCs enhances their survival and can be employed to improve therapeutic efficacy of CSCs for ischemic heart disease.

Stem and Progenitor Cells in Human Cardiopulmonary Development and Regeneration

Already during embryonic development, the heart and the lung are thoroughly connected organs. Their interdependence allows our survival in the terrestrial environment by coupling cardiac output and gas exchange. The knowledge on developmental processes involving stem and progenitor cells is crucial to understand the onset of human cardiopulmonary diseases. The precise identification of various adult endogenous progenitors is still incomplete. Thus, caution should be exercised on newly available stem cell-based treatments until specific mechanisms of action are disclosed. The objective is to provide in the nearest future feasible and safer cell therapeutics for the complex pathological condition of human cardiopulmonary diseases. In this paper, we highlight the significant knowledge advancement concerning stem and progenitor cells in the cardiopulmonary field: from embryonic development to adult progenitors until early preclinical models for cardiopulmonary regeneration.

Image-guided stem cells with functionalized self-assembling peptide nanofibers for treatment of acute myocardial infarction in a mouse model

AIM

To investigate the survival of bone marrow mesenchymal stem cells (BMSCs) and the therapeutic effect for acute myocardial infarction (AMI) after co-transplantation with the functionalized self-assembling peptide nanofiber RAD/PRG or RAD/KLT.

METHODS

AMI of balb/c mice was induced. Mice were randomly divided into four groups, and received treatment of phosphate buffered saline (PBS) (Group A), GFP/Fluc-BMSCs (Group B), GFP/Fluc-BMSCs + RAD/PRG (Group C), and GFP/Fluc-BMSCs + RAD/KLT (Group D), respectively. Bioluminescence imaging (BLI) was performed on day 1 (d-1), d-4, d-7, d-10, and d-13 after transplantation. Magnetic resonance imaging (MRI) was performed at baseline (d-4 before transplantation) and d-29 after treatment. Mice were euthanized on d-29 following treatment. Paraffin sections were obtained from the top, mid and bottom part of the infarcted region along the long-axis of the heart. Hematoxylin and eosin (HE) staining and immunohistochemical staining were performed. The infarct ratio micro-vascular density (MVD) was quantified.

RESULTS

There was a significant higher of BLI signal intensity of BMSCs in Group C than that in Group B (d-4, 9713±320 vs. 8164±378, P=0.0008; d-7, 6489±241 vs. 5417±361, P=0.0026; d-10, 3768±255 vs. 0, P < 0.0001). The left ventricular ejection fraction (LVEF) via MRI examination was significantly improved in both Group C and Group D. Infarct ratio and MVD were significantly improved in both Group C and Group D.

CONCLUSION

Our data highlights BMSCs combining functionalized self-assembling peptide nanofibers RAD/PRG or RAD/KLT as promising therapy for AMI.

Platelet-Targeted Delivery of Peripheral Blood Mononuclear Cells to the Ischemic Heart Restores Cardiac Function after Ischemia-Reperfusion Injury

One of the major hurdles in intravenous regenerative cell therapy is the low homing efficiency to the area where these cells are needed. To increase cell homing toward areas of myocardial damage, we developed a bispecific tandem single-chain antibody (Tand-scFv_{Sca-1+GPIIb/IIIa}) that binds with high affinity to activated platelets via the activated glycoprotein (GP)IIb/IIIa receptor, and to a subset of peripheral blood mononuclear cells (PBMC) which express the stem cell antigen-1 (Sca-1) receptor. Methods: The Tand-scFv_{Sca-1+GPIIb/IIIa} was engineered, characterized and tested in a mouse model of ischemia-reperfusion (IR) injury applying left coronary artery occlusion for 60 min. Fluorescence cell tracking, cell infiltration studies, echocardiographic and histological analyses were performed. Results: Treatment of mice undergoing myocardial infarction with targeted-PBMCs led to successful cell delivery to the ischemic-reperfused myocardium, followed by a significant decrease in infiltration of inflammatory cells. Homing of targeted-PBMCs as shown by fluorescence cell tracking ultimately decreased fibrosis, increased capillary density, and restored cardiac function 4 weeks after ischemia-reperfusion injury. Conclusion: Tand-scFv_{Sca-1+GPIIb/IIIa} is a promising candidate to enhance therapeutic cell delivery in order to promote myocardial regeneration and thereby preventing heart failure.

A collagen cardiac patch incorporating alginate microparticles permits the controlled release of hepatocyte growth factor and insulin-like growth factor-1 to enhance cardiac stem cell migration and proliferation

Cardiac stem cells (CSCs) represent a logical cell type to exploit as a regenerative treatment option for tissue damage accrued as a result of a myocardial infarction. However, the isolation and expansion of CSCs prior to cell transplantation is time consuming, costly and invasive, and the reliability of cell expansion may also prove to be a major obstacle in the clinical application of CSC-based transplantation therapy after a myocardial infarction. In order to overcome this, we propose the incorporation of growth factor-eluting alginate microparticles into collagen-based scaffolds as an implantable biomaterial to promote the recruitment and expansion of CSCs in the myocardium. In order to obtain scaffolds able to enhance the motogenic and proliferative potential of CSCs, the aim of this work was to achieve a sustained delivery of both hepatocyte growth factor and insulin-like growth factor-1. Both proteins were initially encapsulated in alginate microparticles by spray drying and subsequently incorporated into a collagen scaffold. Microparticles were seen to homogeneously distribute through the interconnected scaffold pore structure. The resulting scaffolds were capable of extending the release of both proteins up to 15 days, a three-fold increase over non-encapsulated proteins embedded in the scaffolds. In vitro assays with isolated CSCs demonstrated that the sustained release of both bioactive proteins resulted in an increased motogenic and proliferative effect. As presently practiced, the isolation and expansion of CSCs for autologous cell transplantation is slow, expensive and difficult to attain. Thus, there is a need for strategies to specifically activate in situ the intrinsic cardiac regenerative potential represented by the CSCs using combinations of growth factors obviating the need for cell transplantation. By favouring the natural regenerative capability of CSCs, it is hypothesized that the cardiac patch presented here will result in positive therapeutic outcomes in MI and heart failure patients in the future. Copyright © 2016 John Wiley & Sons, Ltd.