Intracoronary autologous bone marrow stem cells transfer for patients with acute myocardial infarction: a meta-analysis of randomised controlled trials

Meta-Analysis of Cell Therapy Studies in Heart Failure and Acute Myocardial Infarction

Heart failure (HF) is one of the leading causes of death worldwide and has reached epidemic proportions in most industrialized nations. Despite major improvements in the treatment and management of the disease, the prognosis for patients with HF remains poor with approximately only half of patients surviving for 5 years or longer after diagnosis. The poor prognosis of HF patients is in part because of irreparable damage to cardiac tissue and concomitant maladaptive changes associated with the disease. Cell-based therapies may have the potential to transform the treatment and prognosis of HF through regeneration or repair of damaged cardiac tissue. Accordingly, numerous phase I and II randomized clinical trials have tested the clinical benefits of cell transplant, mostly autologous bone marrow-derived mononuclear cells, in patients with HF, ischemic heart disease, and acute myocardial infarction. Although many of these trials were relatively small, meta-analyses of cell-based therapies have attempted to apply rigorous statistical methodology to assess the potential clinical benefits of the intervention. As a prelude to larger phase III trials, meta-analyses, therefore, remain the obvious means of evaluating the available clinical evidence. Here, we review the different meta-analyses of randomized clinical trials that evaluate the safety and potential beneficial effect of cell therapies in HF and acute myocardial infarction spanning nearly 2 decades since the first pioneering trials were conducted.

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.

Cardiac repair by epicardial EMT: Current targets and a potential role for the primary cilium

Despite therapeutic advances that have prolonged life, myocardial infarction (MI) remains a leading cause of death worldwide and imparts a significant economic burden. The advancement of treatments to improve cardiac repair post-MI requires the discovery of new targeted treatment strategies. Recent studies have highlighted the importance of the epicardial covering of the heart in both cardiac development and lower vertebrate cardiac regeneration. The epicardium serves as a source of cardiac cells including smooth muscle cells, endothelial cells and cardiac fibroblasts. Mammalian adult epicardial cells are typically quiescent. However, the fetal genetic program is reactivated post-MI, and epicardial epithelial-to-mesenchymal transition (EMT) occurs as an inherent mechanism to support neovascularization and cardiac healing. Unfortunately, endogenous EMT is not enough to encourage sufficient repair. Recent developments in our understanding of the mechanisms supporting the EMT process has led to a number of studies directed at augmenting epicardial EMT post-MI. With a focus on the role of the primary cilium, this review outlines the newly demonstrated mechanisms supporting EMT, the role of epicardial EMT in cardiac development, and promising advances in augmenting epicardial EMT as potential therapeutics to support cardiac repair post-MI.

Fifteen years of bone marrow mononuclear cell therapy in acute myocardial infarction

In spite of modern treatment, acute myocardial infarction (AMI) still carries significant morbidity and mortality worldwide. Even though standard of care therapy improves symptoms and also long-term prognosis of patients with AMI, it does not solve the critical issue, specifically the permanent damage of cardiomyocytes. As a result, a complex process occurs, namely cardiac remodeling, which leads to alterations in cardiac size, shape and function. This is what has driven the quest for unconventional therapeutic strategies aiming to regenerate the injured cardiac and vascular tissue. One of the latest breakthroughs in this regard is stem cell (SC) therapy. Based on favorable data obtained in experimental studies, therapeutic effectiveness of this innovative therapy has been investigated in clinical settings. Of various cell types used in the clinic, autologous bone marrow derived SCs were the first used to treat an AMI patient, 15 years ago. Since then, we have witnessed an increasing body of data as regards this cutting-edge therapy. Although feasibility and safety of SC transplant have been clearly proved, it’s efficacy is still under dispute. Conducted studies and meta-analysis reported conflicting results, but there is hope for conclusive answer to be provided by the largest ongoing trial designed to demonstrate whether this treatment saves lives. In the meantime, strategies to enhance the SCs regenerative potential have been applied and/or suggested, position papers and recommendations have been published. But what have we learned so far and how can we properly use the knowledge gained? This review will analytically discuss each of the above topics, summarizing the current state of knowledge in the field.

Stem cell transplantation dose in patients with acute myocardial infarction: A meta-analysis

OBJECTIVE

To evaluate whether stem cell transplantation improves global left ventricular ejection fraction (LVEF) in patients with acute myocardial infarction (AMI), and to determine the appropriate stem cell therapy dose as well as the effective period after stem cell transplantation for therapy.

METHODS

A systematic literature search included Pubmed, MEDLINE, China National Knowledge Infrastructure (CNKI), Chinese Biomedical Literature Database (CBM), and Cochrane Evidence-Based Medicine databases. The retrieval time limit ranged from January 1990 to June 2016. We also obtained full texts through manual retrieval, interlibrary loan and document delivery service, or by contacting the authors directly. According to our inclusion and exclusion criteria, data were extracted independently by two evaluators. In case of disagreement, a joint discussion occurred and a third researcher was utilized. Data were analyzed quantitatively using Revman 5.2. Summary results are presented as the weighted mean difference (WMD) with 95% confidence intervals (CIs). We collected individual trial data and conducted a meta-analysis to compare changes in global left ventricular ejection fraction (ΔLVEF) after stem cell therapy. In this study, four subgroups were based on stem cell dose (≤1 × 10⁷ cells, ≤1 × 10⁸ cells, ≤1 × 10⁹ cells, and ≤1 × 10¹⁰ cells) and three subgroups were based on follow-up time (<6 months, 6-12 months, and ≥12 months).

RESULTS

Thirty-four studies, which included 40 randomized controlled trials, were included in this meta-analysis, and 1927 patients were evaluated. Changes in global LVEF were significantly higher in the stem cell transplantation group than in the control group (95% CI: 2.35-4.26%, P < 0.01). We found no significant differences in ΔLVEF between the bone marrow stem cells (BMCs) group and control group when the dose of BMCs was ≤1 × 10⁷ [ΔLVEF 95% CI: 0.12-3.96%, P = 0.04]. The ΔLVEF in the BMCs groups was significantly higher than in the control groups when the dose of BMCs was ≤1 × 10⁸ [ΔLVEF 95% CI: 0.95-4.25%, P = 0.002] and ≤1 × 10⁹ [ΔLVEF 95% CI: 2.31-4.20%, P < 0.01]. In addition, when the dose of BMCs was between 10⁹ and 10¹⁰ cells, we did not observe any significant differences [ΔLVEF 95% CI: -0.99-11.82%, P = 0.10]. Our data suggest stem cell therapy improves cardiac function in AMI patients when treated with an appropriate dose of BMCs.

CONCLUSION

Stem cell transplantation after AMI could improve global LVEF. Stem cells may be effectively administered to patients with AMI doses between 10⁸ and 10⁹ cells.

Meta-Analyses of Human Cell-Based Cardiac Regeneration Therapies: Controversies in Meta-Analyses Results on Cardiac Cell-Based Regenerative Studies

In contrast to multiple publication-based meta-analyses involving clinical cardiac regeneration therapy in patients with recent myocardial infarction, a recently published meta-analysis based on individual patient data reported no effect of cell therapy on left ventricular function or clinical outcome. A comprehensive review of the data collection, statistics, and the overall principles of meta-analyses provides further clarification and explanation for this controversy. The advantages and pitfalls of different types of meta-analyses are reviewed here. Each meta-analysis approach has a place when pivotal clinical trials are lacking and sheds light on the magnitude of the treatment in a complex healthcare field.

Empowering Adult Stem Cells for Myocardial Regeneration V2.0: Success in Small Steps

Much has changed since our survey of the landscape for myocardial regeneration powered by adult stem cells 4 years ago.(1) The intervening years since that first review has witnessed an explosive expansion of studies that advance both understanding and implementation of adult stem cells in promoting myocardial repair. Painstaking research from innumerable laboratories throughout the world is prying open doors that may lead to restoration of myocardial structure and function in the wake of pathological injury. This global effort has produced deeper mechanistic comprehension coupled with an evolving appreciation for the complexity of myocardial regeneration in the adult context. Undaunted by both known and (as yet) unknown challenges, pursuit of myocardial regenerative medicine mediated by adult stem cell therapy has gathered momentum fueled by tantalizing clues and visionary goals. This concise review takes a somewhat different perspective than our initial treatise, taking stock of the business sector that has become an integral part of the field while concurrently updating state of affairs in cutting edge research. Looking retrospectively at advancement over the years as all reviews eventually must, the fundamental lesson to be learned is best explained by Jonatan Mårtensson: "Success will never be a big step in the future. Success is a small step taken just now."

Electrical effects of stem cell transplantation for ischaemic cardiomyopathy: friend or foe?

Despite advances in other realms of cardiac care, the mortality attributable to ischaemic cardiomyopathy has only marginally decreased over the last 10 years. These findings highlight the growing realization that current pharmacological and device therapies rarely reverse disease progression and rationalize a focus on novel means to reverse, repair and re-vascularize damaged hearts. As such, multiple candidate cell types have been used to regenerate damaged hearts either directly (through differentiation to form new tissue) or indirectly (via paracrine effects). Emerging literature suggests that robust engraftment of electrophysiolgically heterogeneous tissue from transplanted cells comes at the cost of a high incidence of ventricular arrhythmias. Similar electrophysiological studies of haematological stem cells raised early concerns that transplant of depolarized, inexcitable cells that also induce paracrine-mediated electrophysiological remodelling may be pro-arrhythmic. However, meta-analyses suggest that patients receiving haematological stem cells paradoxically may experience a decrease in ventricular arrhythmias, an observation potentially related to the extremely poor long-term survival of injected cells. Finally, early clinical and preclinical data from technologies capable of differentiating to a mature cardiomyocyte phenotype (such as cardiac-derived stem cells) suggests that these cells are not pro-arrhythmic although they too lack robust long-term engraftment. These results highlight the growing understanding that as next generation cell therapies are developed, emphasis should also be placed on understanding possible anti-arrhythmic contributions of transplanted cells while vigilance is needed to predict and treat the inadvertent effects of regenerative cell therapies on the electrophysiological stability of the ischaemic cardiomyopathic heart.

Predictors of ventricular remodelling in patients with reperfused acute myocardial infarction and left ventricular dysfunction candidates for bone marrow cell therapy: insights from the BONAMI trial

PURPOSE

Few data are available regarding the relation of left ventricular (LV) mechanical dyssynchrony to remodelling after acute myocardial infarction (MI) and stem cell therapy. We evaluated the 1-year time course of both LV mechanical dyssynchrony and remodelling in patients enrolled in the BONAMI trial, a randomized, multicenter controlled trial assessing cell therapy in patients with reperfused MI.

METHODS

Patients with acute MI and ejection fraction (EF) ≤ 45 % were randomized to cell therapy or to control and underwent thallium single-photon emission computed tomography (SPECT), radionuclide angiography, and echocardiography at baseline, 3 months, and 1 year. Eighty-three patients with a comprehensive 1-year follow-up were included. LV dyssynchrony was assessed by the standard deviation (SD) of the LV phase histogram using radionuclide angiography. Remodelling was defined as a 20 % increase in LV end-systolic volume index (LVESVI) at 1 year.

RESULTS

At baseline, LVEF, wall motion score index, and perfusion defect size were significantly impaired in the 43 patients (52 %) with LV remodelling (all p < 0.001), without significant increase in LV mechanical dyssynchrony. During follow-up, there was a progressive increase in LV SD (p = 0.01). Baseline independent predictors of LV remodelling were perfusion SPECT defect size (p = 0.001), LVEF (p = 0.01) and a history of hypertension (p = 0.043). Bone marrow cell therapy did not affect the time-course of LV remodelling and dyssynchrony.

CONCLUSIONS

LV remodelling 1 year after reperfused MI is associated with progressive LV dyssynchrony and is related to baseline infarct size and ejection fraction, without impact of cell therapy on this process.

Short-Term Effect of Autologous Bone Marrow Stem Cells to Treat Acute Myocardial Infarction: A Meta-Analysis of Randomized Controlled Clinical Trials

Bone marrow stem cells (BMSCs) have been used to treat patient with ST-segment elevation myocardial infarction (STEMI) via intracoronary route. We performed a meta-analysis to evaluate the short-term efficacy and safety of this modality. Seventeen randomized controlled trials (RCTs) of BMSC-based therapy for STEMI, delivered with 9 days of reperfusion and followed up shorter than 12 months, were identified by systematic review. Intracoronary BMSC therapy resulted in an overall significant improvement in left ventricular ejection fraction (LVEF) by 2.74 % (95 % confidence interval (CI) 2.09-3.39, P < 0.00001, I(2) = 84 %) at 3-6-month follow-up and 5.1 % (95 % CI 4.16-6.03, P < 0.00001 and I(2) = 85 %) at 12 months. The left ventricular end-systolic volume (LVESV) and wall motion score index (WMSI) were also reduced at 3-6 months. At 12 months, left ventricular end-diastolic volume (LVEDV), LVESV, and WMSI were significantly reduced in BMSC group. In conclusion, intracoronary BMSC therapy at post-STEMI is safe and effective in patient with acute STEMI.

Stem cell therapy for cardiovascular disease: the demise of alchemy and rise of pharmacology

Regenerative medicine holds great promise as a way of addressing the limitations of current treatments of ischaemic disease. In preclinical models, transplantation of different types of stem cells or progenitor cells results in improved recovery from ischaemia. Furthermore, experimental studies indicate that cell therapy influences a spectrum of processes, including neovascularization and cardiomyogenesis as well as inflammation, apoptosis and interstitial fibrosis. Thus, distinct strategies might be required for specific regenerative needs. Nonetheless, clinical studies have so far investigated a relatively small number of options, focusing mainly on the use of bone marrow-derived cells. Rapid clinical translation resulted in a number of small clinical trials that do not have sufficient power to address the therapeutic potential of the new approach. Moreover, full exploitation has been hindered so far by the absence of a solid theoretical framework and inadequate development plans. This article reviews the current knowledge on cell therapy and proposes a model theory for interpretation of experimental and clinical outcomes from a pharmacological perspective. Eventually, with an increased association between cell therapy and traditional pharmacotherapy, we will soon need to adopt a unified theory for understanding how the two practices additively interact for a patient's benefit.

Translating stem cell research to cardiac disease therapies: pitfalls and prospects for improvement

Over the past 2 decades, there have been numerous stem cell studies focused on cardiac diseases, ranging from proof-of-concept to phase 2 trials. This series of papers focuses on the legacy of these studies and the outlook for future treatment of cardiac diseases with stem cell therapies. The first section by Drs. Rosen and Myerburg is an independent review that analyzes the basic science and translational strategies supporting the rapid advance of stem cell technology to the clinic, the philosophies behind them, trial designs, and means for going forward that may impact favorably on progress. The second and third sections were collected as responses to the initial section of this review. The commentary by Drs. Francis and Cole discusses the review by Drs. Rosen and Myerburg and details how trial outcomes can be affected by noise, poor trial design (particularly the absence of blinding), and normal human tendencies toward optimism and denial. The final, independent paper by Dr. Marbán takes a different perspective concerning the potential for positive impact of stem cell research applied to heart disease and future prospects for its clinical application. (Compiled by the JACC editors).

Cell therapy for human ischemic heart diseases: critical review and summary of the clinical experiences

A decade ago, stem or progenitor cells held the promise of tissue regeneration in human myocardium, with the expectation that these therapies could rescue ischemic myocyte damage, enhance vascular density and rebuild injured myocardium. The accumulated evidence in 2014 indicates, however, that the therapeutic success of these cells is modest and the tissue regeneration involves much more complex processes than cell-related biologics. As the quest for the ideal cell or combination of cells continues, alternative cell types, such as resident cardiac cells, adipose-derived or phenotypic modified stem or progenitor cells have also been applied, with the objective of increasing both the number and the retention of the reparative cells in the myocardium. Two main delivery routes (intracoronary and percutaneous intramyocardial) of stem cells are currently used preferably for patients with recent acute myocardial infarction or ischemic cardiomyopathy. Other delivery modes, such as surgical or intravenous via peripheral veins or coronary sinus have also been utilized with less success. Due to the difficult recruitment of patients within conceivable timeframe into cardiac regenerative trials, meta-analyses of human cardiac cell-based studies have tried to gather sufficient number of subjects to present a statistical compelling statement, reporting modest success with a mean increase of 0.9-6.1% in left ventricular global ejection fraction. Additionally, nearly half of the long-term studies reported the disappearance of the initial benefit of this treatment. Beside further extensive efforts to increase the efficacy of currently available methods, pre-clinical experiments using new techniques such as tissue engineering or exploiting paracrine effect hold promise to regenerate injured human cardiac tissue.

Combination of CD34-positive cell subsets with infarcted myocardium-like matrix stiffness: a potential solution to cell-based cardiac repair

Detection of the optimal cell transplantation strategy for myocardial infarction (MI) has attracted a great deal of attention. Commitment of engrafted cells to angiogenesis within damaged myocardium is regarded as one of the major targets in cell-based cardiac repair. Bone marrow–derived CD34-positive cells, a well-characterized population of stem cells, might represent highly functional endothelial progenitor cells and result in the formation of new blood vessels. Recently, physical microenvironment (extracellular matrix stiffness) around the engrafted cells was found to exert an essential impact on their fate. Stem cells are able to feel and respond to the tissue-like matrix stiffness to commit to a relevant lineage. Notably, the infarct area after MI experiences a time-dependent stiffness change from flexible to rigid. Our previous observations demonstrated myocardial stiffness-dependent differentiation of the unselected bone marrow–derived mononuclear cells (BMMNCs) along endothelial lineage cells. Myocardial stiffness (∽42 kPa) within the optimal time domain of cell engraftment (at week 1 to 2) after MI provided a more favourable physical microenvironment for cell specification and cell-based cardiac repair. However, the difference in tissue stiffness-dependent cell differentiation between the specific cell subsets expressing and no expressing CD34 phenotype remains uncertain. We presumed that CD34-positive cell subsets facilitated angiogenesis and subsequently resulted in cardiac repair under induction of infarcted myocardium-like matrix stiffness compared with CD34-negative cells. If the hypothesis were true, it would contribute greatly to detect the optimal cell subsets for cell therapy and to establish an optimized therapy strategy for cell-based cardiac repair.

Breakthroughs in cell therapy for heart disease: focus on cardiosphere-derived cells

The clinical reality of cell therapy for heart disease dates back to the 1990 s, when autologous skeletal myoblasts were first transplanted into failing hearts during open-chest surgery. Since then, the focus has shifted to bone marrow-derived cells and, more recently, cells extracted from the heart itself. Although progress has been nonlinear and often disheartening, the field has nevertheless made remarkable progress. Six major breakthroughs are notable: (1) the establishment of safety with intracoronary delivery; (2) the finding that therapeutic regeneration is possible; (3) the increase in allogeneic cell therapy; (4) the effect of increasing mechanistic insights; (5) glimmers of clinical efficacy; and (6) the progression to phase 2 and 3 studies. This article individually reviews these landmark developments in detail and concludes that the field has reached a new phase of maturity where the prospect of clinical impact is increasingly imminent.

A critical challenge: dosage-related efficacy and acute complication intracoronary injection of autologous bone marrow mesenchymal stem cells in acute myocardial infarction

BACKGROUND

Previous studies showed improvement in heart function by injecting bone marrow mesenchymal stem cells (BMSCs) after AMI. Emerging evidence suggested that both the number and function of BMSCs decline with ageing. We designed a randomized, controlled trial to further investigate the safety and efficacy of this treatment.

METHODS

Patients with ST-elevation AMI undergoing successful reperfusion treatment within 12 hours were randomly assigned to receive an intracoronary infusion of BMSCs (n=21) or standard medical treatment (n=22) (the numbers of patients were limited because of the complication of coronary artery obstruction).

RESULTS

There is a closely positive correlation of the number and function of BMSCs vs. the cardiac function reflected by LVEF at baseline (r=0.679, P=0.001) and at 12-month follow-up (r=0.477, P=0.039). Six months after cell administration, myocardial viability within the infarct area by 18-FDG SPECT was improved in both groups compared with baseline, but no significant difference in the BMSCs compared with control groups (4.0±0.4% 95%CI 3.1-4.9 vs. 3.2±0.5% 95%CI 2.1-4.3, P=0.237). 99mTc-sestamibi SPECT demonstrated that myocardial perfusion within the infarct area in the BMSCs did not differ from the control group (4.4±0.5% 95%CI 3.2-5.5 vs. 3.9±0.6% 95%CI 2.6-5.2, P=0.594). Similarly, LVEF after 12 and 24 months follow-up did not show any difference between the two groups. In the BMSCs group, one patient suffered a serious complication of coronary artery occlusion during the BMSCs injection procedure.

CONCLUSIONS

The clinical benefits of intracoronary injection of autologous BMSCs in acute STEMI patients need further investigation and reevaluation.

Clinical trials of cardiac repair with adult bone marrow- derived cells

The past decade has witnessed a marked increase in the number of clinical trials of cardiac repair with adult bone marrow cells (BMCs). These trials included patients with acute myocardial infarction (MI) as well as chronic ischemic heart disease (IHD) and utilized different types of BMCs with variable numbers, routes of administration, and timings after MI. Given these differences in methods, the outcomes from these trials have been often disparate and controversial. However, analysis of pooled data suggests that BMC injection enhances left ventricular function, reduces infarct scar size, and improves remodeling in patients with acute MI as well as chronic IHD. BMC therapy also improves clinical outcomes during follow-up without any increase in adverse effects. Although the underlying mechanisms of heart repair are difficult to elucidate in human studies, valuable insights may be gleaned from subgroup analysis of key variables. This information may be utilized to design future randomized controlled trials to carefully determine the long-term safety and benefits of BMC therapy.

[Current status and future of cell-based therapy for patients with cardiogenic cerebral embolism]

BACKGROUND AND AIM

Cerebral infarction causes permanent neurological damage. Recently, the intravenous administration of bone marrow-derived mononuclear cells has been shown to improve functional recovery through enhanced angiogenesis in an experimental stroke model. Based on these observations, we have started a phase 1/2a clinical trial of cell-based therapy for patients with cardiogenic cerebral embolism.

METHODS

The major inclusion criterion was patients in whom severe cerebral embolism was diagnosed (more than 9 in the NIHSS score on day 7 after the onset of stroke) at age 75 or younger. The patients received 25 ml (low-dose group, n=6) or 50 ml (high-dose group, n=6) of bone marrow aspirate on days 7-10 after the onset of stroke. Autologous bone marrow-derived mononuclear cells were purified by the density gradient method and administered intravenously on the day of cell aspiration. The primary endpoint was safety and improvement of the NIHSS score compared with our historical control.

RESULTS

We treated 6 patients in the low-dose group and 4 patients in the high-dose group. No adverse effects were observed and most of the patients showed a significant improvement in neurological function at 6 months after cell transplantation. No enrolled patients showed worsening of the NIHSS score at 30 days after the treatment compared with the NIHSS score before the treatment.

CONCLUSION

Autologous bone marrow mononuclear cell transplantation is apparently safe and feasible, and it improves functional recovery.

Cardiac Function, Perfusion, Metabolism, and Innervation following Autologous Stem Cell Therapy for Acute ST-Elevation Myocardial Infarction. A FINCELL-INSIGHT Sub-Study with PET and MRI

Purpose: Beneficial mechanisms of bone marrow cell (BMC) therapy for acute ST-segment elevation myocardial infarct (STEMI) are largely unknown in humans. Therefore, we evaluated the feasibility of serial positron emission tomography (PET) and MRI studies to provide insight into the effects of BMCs on the healing process of ischemic myocardial damage. Methods: Nineteen patients with successful primary reteplase thrombolysis (mean 2.4 h after symptoms) for STEMI were randomized for BMC therapy (2.9 × 10⁶ CD34+ cells) or placebo after bone marrow aspiration in a double-blind, multi-center study. Three days post-MI, coronary angioplasty, and paclitaxel eluting stent implantation preceded either BMC or placebo therapy. Cardiac PET and MRI studies were performed 7–12 days after therapies and repeated after 6 months, and images were analyzed at a central core laboratory. Results: In BMC-treated patients, there was a decrease in [¹¹C]-HED defect size (−4.9 ± 4.0 vs. −1.6 ± 2.2%, p = 0.08) and an increase in [¹⁸F]-FDG uptake in the infarct area at risk (0.06 ± 0.09 vs. −0.05 ± 0.16, p = 0.07) compared to controls, as well as less left ventricular dilatation (−4.4 ± 13.3 vs. 8.0 ± 16.7 mL/m², p = 0.12) at 6 months follow-up. However, BMC treatment was inferior to placebo in terms of changes in rest perfusion in the area at risk (−0.09 ± 0.17 vs. 0.10 ± 0.17, p = 0.03) and infarct size (0.4 ± 4.2 vs. −5.1 ± 5.9 g, p = 0.047), and no effect was observed on ejection fraction (p = 0.37). Conclusion: After the acute phase of STEMI, BMC therapy showed only minor trends of long-term benefit in patients with rapid successful thrombolysis. There was a trend of more decrease in innervation defect size and enhanced glucose metabolism in the infarct-related myocardium and also a trend of less ventricular dilatation in the BMC-treated group compared to placebo. However, no consistently better outcome was observed in the BMC-treated group compared to placebo.

[Cell based therapy for patients after cerebral embolism]

Neuronal stem cells are mobilized after cerebral infarction. We had shown that appropriate support of these stem cells, achieved by therapeutic angiogenesis, enhances neurological recovery in experimental stroke model. Based on these observations, we started cell based therapy using autologous bone marrow mononuclear cells for patients after cerebral embolism as phase 1/2a clinical trial. We have treated 6 patients in low dose group (harvest 25 ml of bone marrow cells) and none of them showed treatment-related adverse effects. We are now recruiting another 6 patients in high dose group (harvest 50 ml of bone marrow cells) and are planning to evaluate the effectiveness and safety of the therapy after obtaining the results of all 12 patients.

Tracking stem cells for cardiovascular applications in vivo: focus on imaging techniques

Despite rapid translation of stem cell therapy into clinical practice, the treatment of cardiovascular disease using embryonic stem cells, adult stem and progenitor cells or induced pluripotent stem cells has not yielded satisfactory results to date. Noninvasive stem cell imaging techniques could provide greater insight into not only the therapeutic benefit, but also the fundamental mechanisms underlying stem cell fate, migration, survival and engraftment in vivo. This information could also assist in the appropriate choice of stem cell type(s), delivery routes and dosing regimes in clinical cardiovascular stem cell trials. Multiple imaging modalities, such as MRI, PET, SPECT and CT, have emerged, offering the ability to localize, monitor and track stem cells in vivo. This article discusses stem cell labeling approaches and highlights the latest cardiac stem cell imaging techniques that may help clinicians, research scientists or other healthcare professionals select the best cellular therapeutics for cardiovascular disease management.

Stem cells and stroke: opportunities, challenges and strategies

INTRODUCTION

Stroke remains the leading cause of disability in the Western world. Despite decades of work, no clinically effective therapies exist to facilitate recovery from stroke. Stem cells may have the potential to minimize injury and promote recovery after stroke.

AREAS COVERED

Transplanted stem cells have been shown in animal models to migrate to the injured region, secrete neurotrophic compounds, promote revascularization, enhance plasticity and regulate the inflammatory response, thereby minimizing injury. Endogenous neural stem cells also have a remarkable propensity to respond to injury. Under select conditions, subventricular zone progenitors may be mobilized to replace lost neurons. In response to focal infarcts, neuroblasts play important trophic roles to minimize neural injury. Importantly, these endogenous repair mechanisms may be experimentally augmented, leading to robust improvements in function. Ongoing clinical studies are now assessing the safety and feasibility of cell-based therapies for stroke.

EXPERT OPINION

We outline the unique challenges and potential pitfalls in the clinical translation of stem cell research for stroke. We then detail what we believe to be the specific basic science and clinical strategies needed to overcome these challenges, fill remaining gaps in knowledge and facilitate development of clinically viable stem cell-based therapies for stroke.

Development of bioartificial myocardium using stem cells and nanobiotechnology templates

Cell-based regenerative therapy is undergoing experimental and clinical trials in cardiology, in order to limit the consequences of decreased contractile function and compliance of damaged ventricles following myocardial infarction. Over 1000 patients have been treated worldwide with cell-based procedures for myocardial regeneration. Cellular cardiomyoplasty seems to reduce the size and fibrosis of infarct scars, limit adverse postischemic remodelling, and improve diastolic function. The development of a bioartificial myocardium is a new challenge; in this approach, tissue-engineered procedures are associated with cell therapy. Organ decellularization for bioscaffolds fabrication is a new investigated concept. Nanomaterials are emerging as the main candidates to ensure the achievement of a proper instructive cellular niche with good drug release/administration properties. Investigating the electrophysiological properties of bioartificial myocardium is the challenging objective of future research, associating a multielectrode network to provide electrical stimulation could improve the coupling of grafted cells and scaffolds with host cardiomyocytes. In summary, until now stem cell transplantation has not achieved clear hemodynamic benefits for myocardial diseases. Supported by relevant scientific background, the development of myocardial tissue engineering may constitute a new avenue and hope for the treatment of myocardial diseases.

Ligating LAD with its whole length rather than diagonal branches as coordinates is more advisable in establishing stable myocardial infarction model of swine

A reproducible and reliable myocardial infarction (MI) model with less inter-individual variation in ischemic size and ventricular function is essential in cardiovascular research. Little is known about whether the different ligation coordinates [whole length of left anterior descending artery (LAD) or diagonal branches] affect the inter-individual variation of ventricular function in the MI model. The present study compared the characteristics of the experimental swine MI model induced by surgical occlusion of LAD in two groups: group A (n=24), where ligation was performed below the second ventricular branch (D(2) branch), and group B (n=23), where ligation was performed at a distance one-third distal to the apex. Variation of ischemic size and left ventricular ejection fraction (LVEF) at 4 weeks after MI was compared between the two groups using the homoscedasticity F test and coefficient of variance (CV). Difficulty in identifying ventricular branches and the great variation of branching patterns encumbered the precise ligation of LAD in group A. The ischemic size and LVEF in group B were less variable than those of group A. There were significant correlations between the percentile of LAD ligation and infarct size or ventricular function. In conclusion, ligating LAD using its whole length rather than ventricular branches as coordinates may be more practical and advisable for establishing reproducible MI models, and this procedure may prove to help standardize the location of occlusion and infarct size.

Stem cell labeling for noninvasive delivery and tracking in cardiovascular regenerative therapy

Clinical and basic scientific studies of stem cell-based therapies have shown promising results for cardiovascular diseases. Despite a rapid transition from animal studies to clinical trials, the mechanisms by which stem cells improve heart function are yet to be fully elucidated. To optimize cell therapies in patients will require a noninvasive means to evaluate cell survival, biodistribution and fate in the same subject over time. Cell labeling offers the ability to image distinct cell lineages in vivo and investigate the efficacy of these therapies using standard noninvasive imaging techniques. In this article, we will discuss the most promising cell labeling techniques for translation to clinical cardiovascular applications.

Recent developments and future challenges on imaging for stem cell research

As clinical trials with stem cells for cardiac regenerative therapy move forward, advances in imaging equipment and technique offer powerful methods to evaluate therapeutic efficacy. Methodologies to label stem cells for tracking continue to expand. Non-invasive imaging offers the potential to better understand the interaction of exogenous stem cells with the host to answer questions such as the best cell type(s), timing of delivery, dose, and delivery route. If successful, these techniques may enable individually tailored dosing of stem cell therapeutics. However, techniques that are suitable for animal models of cardiac disease may have hurdles to clinical translation beyond simple biocompatibility issues. Challenges include the high cost of advanced imaging techniques, applicability in acute ischemic disease, and regulatory approval. In this review, we will cover some new imaging techniques and labeling strategies and assess the obstacles to clinical adoption.

Effects of stem cell therapy on left ventricular remodeling after acute myocardial infarction: a meta-analysis

OBJECTIVES

The objective was to perform a meta-analysis of clinical trials that investigated the effects of stem cell therapy on left ventricular remodeling in patients after acute myocardial infarction (AMI).

BACKGROUND

Intracoronary injection of stem cells in the acute phase of myocardial infarction has been proposed to replace the cardiomyocytes lost and to prevent deleterious pathological remodeling after myocardial infarction. Previously published trials have investigated the effects of cell therapy on left ventricular (LV) remodeling in AMI patients. However, the sample size of these studies is small and the conclusions are inconsistent.

METHODS

Trials were identified in the Cochrane Library, EMBASE, and PubMed databases, reviews, and reference lists of relevant articles. The weighted mean difference (WMD) was calculated for net changes in LV end-diastolic and end-systolic volumes (LVEDV and LVESV) by using fixed-effect models.

RESULTS

A total of 11 trials (13 comparisons) with 832 participants evaluated the association between stem cell therapy and changes in LVEDV. Compared with the control group, stem cell therapy did not influence the LVEDV changes from baseline to follow-up (WMD: - 1.76 mL, 95% confidence interval [CI]: - 4.61 to 1.08 mL, P = 0.233). A total of 9 trials (11 comparisons) with 797 participants evaluated the association between stem cell therapy and changes in LVESV. Compared with the control group, patients in the cell therapy group had a significantly greater reduction in LVESV from baseline to follow-up (WMD: - 5.08 mL, 95% CI: - 7.80 to - 2.37 mL, P < 0.001).

CONCLUSION

This meta-analysis suggests that cell therapy improves left ventricular contractility, but has no effect on LV remodeling.

New therapies for the failing heart: trans-genes versus trans-cells

During the past 30 years, hundreds of pharmacological agents have been developed for the treatment of heart failure; yet few of them ultimately have been tested in patients. Such a disconcerting debacle has spurred the search for non pharmacological therapies, including those based on cardiac delivery of transgenes and stem cells. Cardiac gene therapy preceded stem cell therapy by approximately 10 years; however, both of them already have known an initial phase of enormous enthusiasm followed by moderate-to-strong skepticism, not necessarily justified. The aim of the present review is to discuss succinctly some key aspects of these 2 biological therapies and to argue that, after a phase of disillusionment, gene therapy for the failing heart likely will have the chance to regain the stage. In fact, discoveries in stem cell biology might revitalize gene therapy and, vice versa, gene therapy might potentiate synergistically the regenerative capacity of stem cells.

Combination stem cell therapy for heart failure

Patients with congestive heart failure (CHF) that are not eligible for transplantation have limited therapeutic options. Stem cell therapy such as autologous bone marrow, mobilized peripheral blood, or purified cells thereof has been used clinically since 2001. To date over 1000 patients have received cellular therapy as part of randomized trials, with the general consensus being that a moderate but statistically significant benefit occurs. Therefore, one of the important next steps in the field is optimization. In this paper we discuss three ways to approach this issue: a) increasing stem cell migration to the heart; b) augmenting stem cell activity; and c) combining existing stem cell therapies to recapitulate a "therapeutic niche". We conclude by describing a case report of a heart failure patient treated with a combination stem cell protocol in an attempt to augment beneficial aspects of cord blood CD34 cells and mesenchymal-like stem cells.

Impact of timing on efficacy and safetyof intracoronary autologous bone marrow stem cells transplantation in acute myocardial infarction: a pooled subgroup analysis of randomized controlled trials

BACKGROUND

Until now there were no clinical studies or systematic reviews to investigate the impact of timing on efficacy and safety of intracoronary bone marrow stem cell (BMSC) transfer in patients with acute myocardial infarction (AMI).

HYPOTHESIS

Timing of BMSC administration might play an important role in the therapeutic response in AMI patients.

METHODS

A systematic literature search of PubMed, MEDLINE, and Cochrane Evidence-Based Medicine (EBM) databases was made on randomized controlled trials with at least 3-month follow-up data for patients with AMI undergoing emergent percutaneous coronary intervention (PCI) and receiving intracoronary BMSC transfer thereafter.

RESULTS

A total of 7 trials with 660 patients were available for analysis. Compared to baseline level, BMSC transfer at 4 to 7 days post-AMI significantly improved left ventricular ejection fraction (LVEF; 4.63% increase, 95% confidence interval [CI]: 1.00%-8.26%, P = 0.01), reduced left ventricular (LV) end-systolic dimensions (95% CI: - 0.53 - 0.02, P = 0.03), decreased the incidences of revascularization (odds ratio [OR]: 0.60, 95% CI: 0.37-0.97, P = 0.04), decreased the cumulative clinical events of death or recurrent myocardial infarction (OR: 0.32, 95% CI: 0.11-0.95, P = 0.04), and decreased culprit artery restenosis or ventricular arrhythmia (OR: 0.59, 95% CI: 0.36-0.96, P = 0.03) however these improvements did not reach statistical significance in emergent transfer trials (within 24 hour post-AMI). Compared with emergent transfer, intracoronary BMSC therapy at 4 to 7 days also significantly reduced the incidence of revascularization (P for interaction = 0.02).

CONCLUSIONS

BMSC transfer at 4 to 7 days post-AMI was superior to that within 24 hours in improving LVEF, decreasing LV end-systolic dimensions, and reducing the incidence of revascularization.

Intracoronary blood- or bone marrow-derived cell transplantation in patients with ischemic heart disease

Soon after the first experimental scientific investigations of cell transplantation in various animal models of myocardial infarction and left ventricular dysfunction, a growing number of clinical trials evaluated the effects of intracoronary injection of peripheral blood- or bone marrow-derived cells in patients with myocardial infarction or chronic ischemic heart disease. In most of these trials, changes in parameters of left ventricular remodeling over time, such as left ventricular volumes, ejection fraction or infarct size, were used as trial end points, whereas information on mortality and morbidity after cell transplantation is sparse. Several meta-analyses, each including various sets of studies, estimated that intracoronary cell therapy was associated with small reductions in left ventricular end-systolic volumes and a moderate increase in left ventricular ejection fraction of 2.9–6.1% over time compared with control patients. As most of the clinical trials included a limited number of patients, results vary substantially between different studies. When evaluating whether effects of intracoronary cell transplantation on parameters of left ventricular remodeling may be transferable to meaningful consequences in terms of clinical outcome, the following aspects appear to be imperative. Robust data on mortality and clinical events based on a sufficient number of patients are required. Furthermore, effects of cell therapy must be compared with established therapeutic concepts for the treatment of myocardial infarction, such as reperfusion therapy or pharmacological interventions aiming at favorably influencing the remodeling process. Moreover, the potential effects of cell therapy must be evaluated as treatment options additive to established therapeutic strategies.