Autologous Mesenchymal Stem Cells Show More Benefit on Systolic Function Compared to Bone Marrow Mononuclear Cells in a Porcine Model of Chronic Myocardial Infarction

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.

Mapping current research and identifying hotspots on mesenchymal stem cells in cardiovascular disease

BACKGROUND

Mesenchymal stem cells (MSCs) have important research value and broad application prospects in the cardiovascular disease. This study provides information on the latest progress, evolutionary path, frontier research hotspots, and future research developmental trends in this field.

METHODS

A knowledge map was generated by CiteSpace and VOSviewer analysis software based on data obtained from the literature on MSCs in the cardiovascular field.

RESULTS

The USA and China ranked at the top in terms of the percentage of articles, accounting for 34.306% and 28.550%, respectively. The institution with the highest number of research publications in this field was the University of Miami, followed by the Chinese Academy of Medical Sciences and Harvard University. The research institution with the highest ACI value was Harvard University, followed by the Mayo Clinic and the University of Cincinnati. The top three subjects in terms of the number of published articles were cell biology, cardiovascular system cardiology, and research experimental medicine. The journal with the most publications in this field was Circulation Research, followed by Scientific Reports and Biomaterials. The direction of research on MSCs in the cardiovascular system was divided into four parts: (1) tissue engineering, scaffolds, and extracellular matrix research; (2) cell transplantation, differentiation, proliferation, and signal transduction pathway research; (3) assessment of the efficacy of stem cells from different sources and administration methods in the treatment of acute myocardial infarction, myocardial hypertrophy, and heart failure; and (4) exosomes and extracellular vesicles research. Tissue research is the hotspot and frontier in this field.

CONCLUSION

MSC research has presented a gradual upward trend in the cardiovascular field. Multidisciplinary intersection is a characteristic of this field. Engineering and materials disciplines are particularly valued and have received attention from researchers. The progress in multidisciplinary research will provide motivation and technical support for the development of this field.

Mesenchymal Stem Cell Therapy for Ischemic Heart Disease: Systematic Review and Meta-analysis

Background and Objectives

Mesenchymal stem cells (MSC) have emerged as breakthrough treatments for myocardial infarction. However, the efficacy of MSC remains unclear. The aim of the study was to evaluate treatment effect of MSC in terms of mechanical, regenerative, and clinical outcomes for patients with myocardial infarction (MI) using meta-analysis.

Methods

A systematic search and critical review of MEDLINE, EMBASE, and Cochrane database literature published from inception through December 2017 was performed. The inclusion criteria were randomized controlled trials, studies on patients with myocardial infarction, and studies compared with placebo as a control group.

Results

A total of 950 patients from 14 randomized placebo controlled trials were included in the final meta-analysis. MSC treatment showed benefits for mechanical, regenerative, and clinical outcomes. In terms of mechanical outcomes, the LVEF of the MSC treatment group increased by 3.84% (95% CI: 2.32~5.35, I²=43) and the effect was maintained for up to 24 months. Regenerative outcomes were measured by scar mass and WMSI. Scar mass was reduced by −1.13 (95% CI: −1.80 to −0.46, I²=71) and WMSI was reduced by −0.05 (95% CI: −0.07 to −0.03, I²=45) at 6 months after MSC treatment. Mortality rate and incidence of re-hospitalization for HF in MSC group patients trended toward reduced incidence compared to the control group, although this was not statistically significant because of the low event rate.

Conclusions

The findings of this meta-analysis indicate that MSCs can be beneficial in improving heart function in the treatment of MI. However, the efficacy of MSCs must be further explored through large randomized controlled trials based on rigorous research design.

Exosomes Generated From iPSC-Derivatives: New Direction for Stem Cell Therapy in Human Heart Diseases

Cardiovascular disease (CVD) is the leading cause of death in modern society. The adult heart innately lacks the capacity to repair and regenerate the damaged myocardium from ischemic injury. Limited understanding of cardiac tissue repair process hampers the development of effective therapeutic solutions to treat CVD such as ischemic cardiomyopathy. In recent years, rapid emergence of induced pluripotent stem cells (iPSC) and iPSC-derived cardiomyocytes presents a valuable opportunity to replenish the functional cells to the heart. The therapeutic effects of iPSC-derived cells have been investigated in many preclinical studies. However, the underlying mechanisms of iPSC-derived cell therapy are still unclear, and limited engraftment of iPSC-derived cardiomyocytes is well known. One facet of their mechanism is the paracrine effect of the transplanted cells. Microvesicles such as exosomes secreted from the iPSC-derived cardiomyocytes exert protective effects by transferring the endogenous molecules to salvage the injured neighboring cells by regulating apoptosis, inflammation, fibrosis, and angiogenesis. In this review, we will focus on the current advances in the exosomes from iPSC derivatives and discuss their therapeutic potential in the treatment of CVD.

Mesenchymal Stem Cell Therapy for the Treatment of Heart Failure Caused by Ischemic or Non-ischemic Cardiomyopathy: Immunosuppression and Its Implications

HF patients with signs and symptoms of worsening heart failure (HF), despite optimal medical therapy, have a poor prognosis. The pathways contributing to HF are multiple, probably accounting, in part, for current treatment approaches not being more effective. Stem cells, particularly mesenchymal stem cells (MSCs), have a broad range of activities, making them particularly interesting candidates for a new HF therapeutic. This review presents an overview of the studies examining the efficacy of stem cell studies administered to HF patients, focusing mainly on MSCs. It examines the issues surrounding autologous vs. allogenic stem cells, the results of different routes of administration, and implications deriving from the belief that for stem cells to be effective, they must engraft in the myocardium and exert local effects. Since intravenous administration of stem cells leads to sparse cardiac engraftment, stem cell delivery strategies have uniformly involved catheter-based delivery systems. This becomes problematic in a disease that will almost certainly require delivery of the therapeutic throughout the course of the disease. Importantly, it appears that a critical contributing cause of the progressive cardiac dysfunction experienced by HF patients is the existence of a persistent inflammatory response. Since MSCs exert potent anti-inflammatory effects through paracrine mechanisms, it is possible that intravenous delivery of MSCs may be therapeutically effective. If this concept is valid, it could lead to a transformational change in stem cell delivery strategies.

Route of Delivery Modulates the Efficacy of Mesenchymal Stem Cell Therapy for Myocardial Infarction: A Meta-Analysis of Preclinical Studies and Clinical Trials

RATIONALE

Accumulating data support a therapeutic role for mesenchymal stem cell (MSC) therapy; however, there is no consensus on the optimal route of delivery.

OBJECTIVE

We tested the hypothesis that the route of MSC delivery influences the reduction in infarct size and improvement in left ventricular ejection fraction (LVEF).

METHODS AND RESULTS

We performed a meta-analysis investigating the effect of MSC therapy in acute myocardial infarction (AMI) and chronic ischemic cardiomyopathy preclinical studies (58 studies; n=1165 mouse, rat, swine) which revealed a reduction in infarct size and improvement of LVEF in all animal models. Route of delivery was analyzed in AMI swine studies and clinical trials (6 clinical trials; n=334 patients). In AMI swine studies, transendocardial stem cell injection reduced infarct size (n=49, 9.4% reduction; 95% confidence interval, -15.9 to -3.0), whereas direct intramyocardial injection, intravenous infusion, and intracoronary infusion indicated no improvement. Similarly, transendocardial stem cell injection improved LVEF (n=65, 9.1% increase; 95% confidence interval, 3.7 to 14.5), as did direct intramyocardial injection and intravenous infusion, whereas intracoronary infusion demonstrated no improvement. In humans, changes of LVEF paralleled these results, with transendocardial stem cell injection improving LVEF (n=46, 7.0% increase; 95% confidence interval, 2.7 to 11.3), as did intravenous infusion, but again intracoronary infusion demonstrating no improvement.

CONCLUSIONS

MSC therapy improves cardiac function in animal models of both AMI and chronic ischemic cardiomyopathy. The route of delivery seems to play a role in modulating the efficacy of MSC therapy in AMI swine studies and clinical trials, suggesting the superiority of transendocardial stem cell injection because of its reduction in infarct size and improvement of LVEF, which has important implications for the design of future studies.

Towards the standardization of stem cell therapy studies for ischemic heart diseases: Bridging the gap between animal models and the clinical setting

Today there is an increasing demand for heart transplantations for patients diagnosed with heart failure. Though, shortage of donors as well as the large number of ineligible patients hurdle such treatment option. This, in addition to the considerable number of transplant rejections, has driven the clinical research towards the field of regenerative medicine. Nonetheless, to date, several stem cell therapies tested in animal models fall by the wayside and when they meet the criteria to clinical trials, subjects often exhibit modest improvements. A main issue slowing down the admission of such therapies in the domain of human trials is the lack of protocol standardization between research groups, which hampers comparison between different approaches as well as the lack of thought regarding the clinical translation. In this sense, given the large amount of reports on stem cell therapy studies in animal models reported in the last 3years, we sought to evaluate their advantages and limitations towards the clinical setting and provide some suggestions for the forthcoming investigations. We expect, with this review, to start a new paradigm on regenerative medicine, by evoking the debate on how to plan novel stem cell therapy studies with animal models in order to achieve more consistent scientific production and accelerate the admission of stem cell therapies in the clinical setting.

Therapeutic use of stem cells for cardiovascular disease

Stem cell treatments are a desirable therapeutic option to regenerate myocardium and improve cardiac function after myocardial infarction. Several different types of cells have been explored, each with their own benefits and limitations. Induced pluripotent stem cells possess an embryonic-like state and therefore have a high proliferative capacity, but they also pose a risk of teratoma formation. Mesenchymal stem cells have been investigated from both bone marrow and adipose tissue. Their immunomodulatory characteristics may permit the use of allogeneic cells as universal donor cells in the future. Lastly, studies have consistently shown that cardiac stem cells are better able to express markers of cardiogenesis compared to other cell types, as well improve cardiac function. The ideal source of stem cells depends on multiple factors such as the ease of extraction/isolation, effectiveness of engraftment, ability to differentiate into cardiac lineages and effect on cardiac function. Although multiple studies highlight the benefits and limitations of each cell type and reinforce the successful potential use of these cells to regenerate damaged myocardium, more studies are needed to directly compare cells from various sources. It is interesting to note that research using stem cell therapies is also expanding to treat other cardiovascular diseases including non-ischemic cardiomyopathies.

Mesenchymal stem cells in cardiac regeneration: a detailed progress report of the last 6 years (2010-2015)

Mesenchymal stem cells have been used for cardiovascular regenerative therapy for decades. These cells have been established as one of the potential therapeutic agents, following several tests in animal models and clinical trials. In the process, various sources of mesenchymal stem cells have been identified which help in cardiac regeneration by either revitalizing the cardiac stem cells or revascularizing the arteries and veins of the heart. Although mesenchymal cell therapy has achieved considerable admiration, some challenges still remain that need to be overcome in order to establish it as a successful technique. This in-depth review is an attempt to summarize the major sources of mesenchymal stem cells involved in myocardial regeneration, the significant mechanisms involved in the process with a focus on studies (human and animal) conducted in the last 6 years and the challenges that remain to be addressed.

Position Paper of the European Society of Cardiology Working Group Cellular Biology of the Heart: cell-based therapies for myocardial repair and regeneration in ischemic heart disease and heart failure

Despite improvements in modern cardiovascular therapy, the morbidity and mortality of ischaemic heart disease (IHD) and heart failure (HF) remain significant in Europe and worldwide. Patients with IHD may benefit from therapies that would accelerate natural processes of postnatal collateral vessel formation and/or muscle regeneration. Here, we discuss the use of cells in the context of heart repair, and the most relevant results and current limitations from clinical trials using cell-based therapies to treat IHD and HF. We identify and discuss promising potential new therapeutic strategies that include ex vivo cell-mediated gene therapy, the use of biomaterials and cell-free therapies aimed at increasing the success rates of therapy for IHD and HF. The overall aim of this Position Paper of the ESC Working Group Cellular Biology of the Heart is to provide recommendations on how to improve the therapeutic application of cell-based therapies for cardiac regeneration and repair.