Randomized, double-blind pilot study of transendocardial injection of autologous aldehyde dehydrogenase-bright stem cells in patients with ischemic heart failure

Optimal effectiveness of heart failure management - an umbrella review of meta-analyses examining the effectiveness of interventions to reduce (re)hospitalizations in heart failure

Heart failure (HF) is a major health concern, which accounts for 1-2% of all hospital admissions. Nevertheless, there remains a knowledge gap concerning which interventions contribute to effective prevention of HF (re)hospitalization. Therefore, this umbrella review aims to systematically review meta-analyses that examined the effectiveness of interventions in reducing HF-related (re)hospitalization in HFrEF patients. An electronic literature search was performed in PubMed, Web of Science, PsycInfo, Cochrane Reviews, CINAHL, and Medline to identify eligible studies published in the English language in the past 10 years. Primarily, to synthesize the meta-analyzed data, a best-evidence synthesis was used in which meta-analyses were classified based on level of validity. Secondarily, all unique RCTS were extracted from the meta-analyses and examined. A total of 44 meta-analyses were included which encompassed 186 unique RCTs. Strong or moderate evidence suggested that catheter ablation, cardiac resynchronization therapy, cardiac rehabilitation, telemonitoring, and RAAS inhibitors could reduce (re)hospitalization. Additionally, limited evidence suggested that multidisciplinary clinic or self-management promotion programs, beta-blockers, statins, and mitral valve therapy could reduce HF hospitalization. No, or conflicting evidence was found for the effects of cell therapy or anticoagulation. This umbrella review highlights different levels of evidence regarding the effectiveness of several interventions in reducing HF-related (re)hospitalization in HFrEF patients. It could guide future guideline development in optimizing care pathways for heart failure patients.

The sham effect of invasive interventions in chronic coronary syndromes: a systematic review and meta-analysis

BACKGROUND

Some patients with chronic coronary syndromes undergo invasive procedures but the efficacy of such interventions remains to be robustly established by randomised sham-controlled trials (RCTs).

PURPOSE

To determine the sham effect in patients with chronic coronary syndromes enrolled in RCTs by performing a systematic review and meta-analysis.

METHODS

In April 2022, we performed a literature search for published patient-blind RCTs (CENTRAL, MEDLINE®, PsycINFO, and reference lists) with sham procedures, reporting the pre-post effects in the invasive sham arm among patients with Canadian cardiovascular society (CCS) angina or angina equivalents.

RESULTS

16 RCTs were included with 546 patients in the sham arm. Pooled results showed that sham interventions were associated with: improvement of 7% (95% CI 2-11%; I2 = 0%) in exercise time; decrease of 0.78 (95% CI - 1.10 to - 0.47; I2 = 75%) in CCS angina class; decrease of 53% (95% CI 24-71%; I2 = 96%) and 25% (95% CI 20-29%; I2 = 0%) in anginal episodes and nitroglycerine (NTG) use, respectively. Pooled results also showed an improvement in the physical functioning, angina frequency, treatment satisfaction, and disease perception domains of the Seattle Angina Questionnaire (SAQ).

CONCLUSION

Sham interventions in patients with chronic coronary syndromes were associated with a significant decrease in anginal episodes, NTG use, and CCS angina class and increased SAQ quality of life and exercise time. These results highlight the need for previous non sham-controlled trials to be interpreted with caution, and the importance of new invasive interventions to be evaluated versus a sham procedure.

Impact of procedural variability and study design quality on the efficacy of cell-based therapies for heart failure - a meta-analysis

BACKGROUND

Cell-based therapy has long been considered a promising strategy for the treatment of heart failure (HF). However, its effectiveness in the clinical setting is now doubted. Because previous meta-analyses provided conflicting results, we sought to review all available data focusing on cell type and trial design.

METHODS AND FINDINGS

The electronic databases PubMed, Cochrane library, ClinicalTrials.gov, and EudraCT were searched for randomized controlled trials (RCTs) utilizing cell therapy for HF patients from January 1, 2000 to December 31, 2020. Forty-three RCTs with 2855 participants were identified. The quality of the reported study design was assessed by evaluating the risk-of-bias (ROB). Primary outcomes were defined as mortality rate and left ventricular ejection fraction (LVEF) change from baseline. Secondary outcomes included both heart function data and clinical symptoms/events. Between-study heterogeneity was assessed using the I2 index. Subgroup analysis was performed based on HF type, cell source, cell origin, cell type, cell processing, type of surgical intervention, cell delivery routes, cell dose, and follow-up duration. Only 10 of the 43 studies had a low ROB for all method- and outcome parameters. A higher ROB was associated with a greater increase in LVEF. Overall, there was no impact on mortality for up to 12 months follow-up, and a clinically irrelevant average LVEF increase by LVEF (2.4%, 95% CI = 0.75-4.05, p = 0.004). Freshly isolated, primary cells tended to produce better outcomes than cultured cell products, but there was no clear impact of the cell source tissue, bone marrow cell phenotype or cell chricdose (raw or normalized for CD34+ cells). A meaningful increase in LVEF was only observed when cell therapy was combined with myocardial revascularization.

CONCLUSIONS

The published results suggest a small increase in LVEF following cell therapy for heart failure, but publication bias and methodologic shortcomings need to be taken into account. Given that cardiac cell therapy has now been pursued for 20 years without real progress, further efforts should not be made.

STUDY REGISTRY NUMBER

This meta-analysis is registered at the international prospective register of systematic reviews, number CRD42019118872.

Impact of Diabetes Mellitus on the Potential of Autologous Stem Cells and Stem Cell-Derived Microvesicles to Repair the Ischemic Heart

Ischemic heart disease remains the leading cause of morbidity and mortality worldwide. Despite the advances in medical management and catheter-based therapy, mortality remains high, as does the risk of developing heart failure. Regenerative therapies have been widely used as an alternative option to repair the damaged heart mainly because of their paracrine-related beneficial effects. Although cell-based therapy has been demonstrated as feasible and safe, randomized controlled trials and meta-analyses show little consistent benefit from treatments with adult-derived stem cells. Mounting evidence from our group and others supports that cardiovascular risk factors and comorbidities impair stem cell potential thus hampering their autologous use. This review aims to better understand the influence of diabetes on stem cell potential. For this purpose, we will first discuss the most recent advances in the mechanistic understanding of the effects of diabetes on stem cell phenotype, function, and molecular fingerprint to further elaborate on diabetes-induced alterations in stem cell extracellular vesicle profile. Although we acknowledge that multiple sources of stem or progenitor cells are used for regenerative purposes, we will focus on bone marrow hematopoietic stem/progenitor cells, mesenchymal stem cells residing in the bone marrow, and adipose tissue and briefly discuss endothelial colony-forming cells.

Revisiting Stem Cell-Based Clinical Trials for Ischemic Stroke

Stroke is the leading cause of serious long-term disability, significantly reducing mobility in almost half of the affected patients aged 65 years and older. There are currently no proven neurorestorative treatments for chronic stroke. To address the complex problem of restoring function in ischemic brain tissue, stem cell transplantation-based therapies have emerged as potential restorative therapies. Aligning with the major cell types found within the ischemic brain, stem-cell-based clinical trials for ischemic stroke have fallen under three broad cell lineages: hematopoietic, mesenchymal, and neural. In this review article, we will discuss the scientific rationale for transplanting cells from each of these lineages and provide an overview of published and ongoing trials using this framework.

Prolonged therapeutic effects of photoactivated adipose-derived stem cells following ischaemic injury

AIM

Adipose-derived stem cells (ASCs) therapies are emerging as a promising approach to therapeutic angiogenesis. Therapeutic persistence and reduced primitive stem cell function following cell delivery remains a critical hurdle for the clinical translation of stem cells in current approaches.

METHODS

Cultured ASCs were derived from subcutaneous white adipose tissue isolated from mice fed a normal diet (ND). Unilateral hindlimb ischaemia model was induced in high-fat diet (HFD)-fed mice by femoral artery interruption, after which photoactivated and non-light-treated ASCs were injected into the tail vein of mice. Laser Doppler imaging was conducted to measure the blood flow reperfusion. Capillary density was measured in the ischaemic gastrocnemius muscle. mRNA levels of angiogenic factors were determined by reverse-transcription polymerase chain reaction. Flow cytometry was used to determine the characterization of ASCs and endothelial progenitor cell (EPC). Human ASCs secretomes were analysed by liquid chromatography tandem mass spectrometry.

RESULTS

Our study demonstrated that photoactivated ND-ASCs prolonged functional blood flow perfusion and increased ASCs-derived EPC and neovascularization 38 days after ligation, when compared with saline-treated controls. Profiling analysis in ischaemic muscles showed upregulation of genes associated with pro-angiogenic factors after injection of photoactivated ND-ASCs when compared with the non-light-treated ASCs or saline treated HFD mice. Mass spectrometry revealed that light-treated ASCs conditioned medium retained a more complete pro-angiogenic activity with significant upregulation of angiogenesis related proteins.

CONCLUSION

Our data demonstrates that photoactivated ND-ASCs improve blood flow recovery and their injection may prove to be a useful strategy for the prevention and treatment of diabetic peripheral arterial disease.

Clinical Safety Profile of Transendocardial Catheter Injection Systems: A Plea for Uniform Reporting

OBJECTIVES

The aim of this study was to characterize the clinical safety profile of transendocardial injection catheters (TIC) reported in the published literature.

BACKGROUND

Transendocardial delivery is a minimally invasive approach to deliver potential therapeutic agents directly into the myocardium. The rate of adverse events across TIC is uncertain.

METHODS

A systematic search was performed for trial publications using TIC. Procedure-associated adverse event data were abstracted, pooled and compared across catheters for active treatment and placebo injected patients. The transendocardial injection associated serious adverse events (TEI-SAE) was defined as the composite of death, myocardial infarction, stroke or transient ischemic attack within 30 days and cardiac perforation causing death or requiring evacuation, serious intraprocedural arrhythmias and serious coronary artery or peripheral vascular complications.

RESULTS

The search identified 4 TIC systems: a helical needle (HN), an electro-anatomically tracked straight needle (EAM-SN), a straight needle without tracking elements (SN), and a curved needle (CN). Of 1799 patients who underwent transendocardial injections, the combined TEI-SAE was 3.4% across all catheters, and 1.1%, 3.3%, 7.1%, and 8.3% for HN, EAM-SN, SN and CN, respectively. However, TIC procedure duration and post procedural cardiac biomarker levels were reported in only 24% and 36% of published trials, respectively.

CONCLUSIONS

Transendocardial injection is associated with varied TEI-SAE but the data are very limited. The HN catheter appeared to be associated with lower TEI-SAE, versus other catheters. Procedure duration and post procedure cardiac biomarker levels were under-reported. Clearly, standardized, procedure-related event reporting for trials involving transcatheter delivery would improve our understanding of complications across different systems.

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.

Aldehyde Dehydrogenase 2 and Heart Failure

Heart failure (HF) is a structural or functional cardiac abnormal syndrome characterized with series of symptoms and signs such as breathlessness, fatigue, pulmonary crackles, and peripheral edema. Being a terminal phase of most myocardial lesions, HF has become a leading cause of mobility and mortality worldwide, associated with heavy clinical burden and economic costs affecting over 23 million people [14]. There is an increase to 5.5% with systolic dysfunction and an increase to 36.0% with diastolic dysfunction in people 60 years or older [85]. The costs accompanied with heart failure stand 2-3% of the total healthcare system expenditure in high-income countries and are expected to increase >2-fold in the next 2 decades [34].

Animal- and human-based evidence for the protective effects of stem cell therapy against cardiovascular disorders

The increasing rate of mortality and morbidity because of cardiac diseases has called for efficient therapeutic needs. With the advancement in cell-based therapies, stem cells are abundantly studied in this area. Nearly, all sources of stem cells are experimented to treat cardiac injuries. Tissue engineering has also backed this technique by providing an advantageous platform to improve stem cell therapy. After in vitro studies, primary treatment-based research studies comprise small and large animal studies. Furthermore, these studies are implemented in human models in the form of clinical trials. Purpose of this review is to highlight the animal- and human-based studies, exploiting various stem cell sources, to treat cardiovascular disorders.

Effect of stem cell transplantation on patients with ischemic heart failure: a systematic review and meta-analysis of randomized controlled trials

Stem cell transplantation (SCT) has become a promising way to treat ischemic heart failure (IHF). We performed a large-scale meta-analysis of randomized clinical trials to investigate the efficacy and safety of SCT in IHF patients. Randomized controlled trials (RCTs) involving stem cell transplantation for the treatment of IHF were identified by searching the PubMed, EMBASE, SpringerLink, Web of Science, and Cochrane Systematic Review databases as well as from reviews and the reference lists of relevant articles. Fourteen eligible randomized controlled trials were included in this study, for a total of 669 IHF patients, of which 380 patients were treated with SCT. The weighted mean difference (WMD) was calculated for changes in the New York Heart Association (NYHA) class, left ventricular ejection fraction (LVEF), left ventricular end-diastolic and end-systolic volumes (LVEDV and LVESV), and Canadian Cardiovascular Society (CCS) angina grade using a fixed effects model, while relative risk (RR) was used for mortality. Compared with the control group, SCT significantly lowered the NYHA class (MD = − 0.73, 95% CI − 1.32 to − 0.14, P < 0.05), LVESV (MD = − 14.80, 95% CI − 20.88 to − 8.73, P < 0.05), and CCS grade (MD = − 0.81, 95% CI − 1.45 to − 0.17, P < 0.05). Additionally, SCT increased LVEF (MD = 6.55, 95% CI 5.93 to 7.16, P < 0.05). However, LVEDV (MD = − 0.33, 95% CI − 1.09 to 0.44, P > 0.05) and mortality (RR = 0.86, 95% CI 0.45 to 1.66, P > 0.05) did not differ between the two groups. This meta-analysis suggests that SCT may contribute to the improvement of LVEF, as well as the reduction of the NYHA class, CCS grade, and LVESV. In addition, SCT does not affect mortality.

Aldehyde Dehydrogenases: Not Just Markers, but Functional Regulators of Stem Cells

Aldehyde dehydrogenase (ALDH) is a superfamily of enzymes that detoxify a variety of endogenous and exogenous aldehydes and are required for the biosynthesis of retinoic acid (RA) and other molecular regulators of cellular function. Over the past decade, high ALDH activity has been increasingly used as a selectable marker for normal cell populations enriched in stem and progenitor cells, as well as for cell populations from cancer tissues enriched in tumor-initiating stem-like cells. Mounting evidence suggests that ALDH not only may be used as a marker for stem cells but also may well regulate cellular functions related to self-renewal, expansion, differentiation, and resistance to drugs and radiation. ALDH exerts its functional actions partly through RA biosynthesis, as all-trans RA reverses the functional effects of pharmacological inhibition or genetic suppression of ALDH activity in many cell types in vitro. There is substantial evidence to suggest that the role of ALDH as a stem cell marker comes down to the specific isoform(s) expressed in a particular tissue. Much emphasis has been placed on the ALDH1A1 and ALDH1A3 members of the ALDH1 family of cytosolic enzymes required for RA biosynthesis. ALDH1A1 and ALDH1A3 regulate cellular function in both normal stem cells and tumor-initiating stem-like cells, promoting tumor growth and resistance to drugs and radiation. An improved understanding of the molecular mechanisms by which ALDH regulates cellular function will likely open new avenues in many fields, especially in tissue regeneration and oncology.

Intramyocardial bone marrow cell injection does not lead to functional improvement in patients with chronic ischaemic heart failure without considerable ischaemia

Background

It has been suggested that bone marrow cell injection may have beneficial effects in patients with chronic ischaemic heart disease. However, previous trials have led to discrepant results of cell-based therapy in patients with chronic heart failure. The aim of this study was to evaluate the efficacy of intramyocardial injection of mononuclear bone marrow cells in patients with chronic ischaemic heart failure with limited stress-inducible myocardial ischaemia.

Methods and results

This multicentre, randomised, placebo-controlled trial included 39 patients with no-option chronic ischaemic heart failure with a follow-up of 12 months. A total of 19 patients were randomised to autologous intramyocardial bone marrow cell injection (cell group) and 20 patients received a placebo injection (placebo group). The primary endpoint was the group difference in change of left ventricular ejection fraction, as determined by single-photon emission tomography. On follow-up at 3 and 12 months, change of left ventricular ejection fraction in the cell group was comparable with change in the placebo group (P = 0.47 and P = 0.08, respectively). Also secondary endpoints, including left ventricle volumes, myocardial perfusion, functional and clinical parameters did not significantly change in the cell group as compared to placebo. Neither improvement was demonstrated in a subgroup of patients with stress-inducible ischaemia (P = 0.54 at 3‑month and P = 0.15 at 12-month follow-up).

Conclusion

Intramyocardial bone marrow cell injection does not improve cardiac function, nor functional and clinical parameters in patients with severe chronic ischaemic heart failure with limited stress-inducible ischaemia.

Clinical Trial Registration: NTR2516

Electronic supplementary material

The online version of this article (10.1007/s12471-018-1213-2) contains supplementary material, which is available to authorized users.

Stem/Progenitor Cells and Their Therapeutic Application in Cardiovascular Disease

Cardiovascular disease is the leading cause of death in the world. The stem/progenitor cell-based therapy has emerged as a promising approach for the treatment of a variety of cardiovascular diseases including myocardial infarction, stroke, peripheral arterial disease, and diabetes. An increasing number of evidence has shown that stem/progenitor cell transplantation could replenish damaged cells, improve cardiac and vascular functions, and repair injured tissues in many pre-clinical studies and clinical trials. In this review, we have outlined the major types of stem/progenitor cells, and summarized the studies in applying these cells, especially endothelial stem/progenitor cells and their derivatives, in the treatment of cardiovascular disease. Here the strategies used to improve the stem/progenitor cell-based therapies in cardiovascular disease and the challenges with these therapies in clinical applications are also reviewed.

Sulfiredoxin-1 enhances cardiac progenitor cell survival against oxidative stress via the upregulation of the ERK/NRF2 signal pathway

Cardiac stem/progenitor cells (CPCs) have recently emerged as a potentially transformative regenerative medicine to repair the infarcted heart. However, the limited survival of donor cells is one of the major challenges for CPC therapy. Our recent research effort on preconditioning human CPCs (hCPCs) with cobalt protoporphyrin (CoPP) indicated that sulfiredoxin-1 (SRXN1) is upregulated upon preconditioning aldehyde dehydrogenase bright hCPCs (ALDH^br-hCPCs) with CoPP. Further studies demonstrated that overexpressing SRXN1 enhanced the survival capacity for ALDH^br-hCPCs. This was associated with the up-regulation of anti-apoptotic factors, including BCL2 and BCL-xL. Meanwhile, overexpressing SRXN1 decreased the ROS generation and mitochondrial membrane potential, concomitant with the up-regulated primary antioxidant systems, such as PRDX1, PRDX3, TXNRD1, Catalase and SOD2. It was also observed that overexpressing SRXN1 increased the migration, proliferation, and cardiac differentiation of ALDH^br-hCPCs. Interestingly, SRXN1 activated the ERK/NRF2 cell survival signaling pathway, which may be the underlying mechanism through which overexpressing SRXN1 lead to protection of hCPCs against oxidative stress-induced apoptosis. Taken together, these results provide a rationale for the exploration of SRXN1 as a novel molecular target that can be used to enhance the effectiveness of cardiac stem/progenitor cell therapy for ischemic heart disease.

ALDH1A3 Is the Key Isoform That Contributes to Aldehyde Dehydrogenase Activity and Affects in Vitro Proliferation in Cardiac Atrial Appendage Progenitor Cells

High aldehyde dehydrogenase (ALDH^hi) activity has been reported in normal and cancer stem cells. We and others have shown previously that human ALDH^hi cardiac atrial appendage cells are enriched with stem/progenitor cells. The role of ALDH in these cells is poorly understood but it may come down to the specific ALDH isoform(s) expressed. This study aimed to compare ALDH^hi and ALDH^lo atrial cells and to identify the isoform(s) that contribute to ALDH activity, and their functional role.

Methods and Results: Cells were isolated from atrial appendage specimens from patients with ischemic and/or valvular heart disease undergoing heart surgery. ALDH^hi activity assessed with the Aldefluor reagent coincided with primitive surface marker expression (CD34⁺). Depending on their ALDH activity, RT-PCR analysis of ALDH^hi and ALDH^lo cells demonstrated a differential pattern of pluripotency genes (Oct 4, Nanog) and genes for more established cardiac lineages (Nkx2.5, Tbx5, Mef2c, GATA4). ALDH^hi cells, but not ALDH^lo cells, formed clones and were culture-expanded. When cultured under cardiac differentiation conditions, ALDH^hi cells gave rise to a higher number of cardiomyocytes compared with ALDH^lo cells. Among 19 ALDH isoforms known in human, ALDH1A3 was most highly expressed in ALDH^hi atrial cells. Knocking down ALDH1A3, but not ALDH1A1, ALDH1A2, ALDH2, ALDH4A1, or ALDH8A1 using siRNA decreased ALDH activity and cell proliferation in ALDH^hi cells. Conversely, overexpressing ALDH1A3 with a retroviral vector increased proliferation in ALDH^lo cells.

Conclusions: ALDH1A3 is the key isoform responsible for ALDH activity in ALDH^hi atrial appendage cells, which have a propensity to differentiate into cardiomyocytes. ALDH1A3 affects in vitro proliferation of these cells.

Foreskin-derived mesenchymal stromal cells with aldehyde dehydrogenase activity: isolation and gene profiling

Background

Mesenchymal stromal cells (MSCs) become an attractive research topic because of their crucial roles in tissue repair and regenerative medicine. Foreskin is considered as a valuable tissue source containing immunotherapeutic MSCs (FSK-MSCs).

Results

In this work, we used aldehyde dehydrogenase activity (ALDH) assay (ALDEFLUOR™) to isolate and therefore characterize subsets of FSK-MSCs. According to their ALDH activity, we were able to distinguish and sort by fluorescence activated cell sorting (FACS) two subsets of FSK-MSCs (referred as ALDH⁺ and ALDH⁻). Consequently, these subsets were characterized by profiling the gene expression related to the main properties of MSCs (proliferation, response to hypoxia, angiogenesis, phenotype, stemness, multilineage, hematopoiesis and immunomodulation). We thus demonstrated by Real Time PCR several relevant differences in gene expression based on their ALDH activity.

Conclusion

Taken together, this preliminary study suggests that distinct subsets of FSK-MSCs with differential gene expression profiles depending of ALDH activity could be identified. These populations could differ in terms of biological functionalities involving the selection by ALDH activity as useful tool for potent therapeutic applications. However, functional studies should be conducted to confirm their therapeutic relevance.

Electronic supplementary material

The online version of this article (10.1186/s12860-018-0157-0) contains supplementary material, which is available to authorized users.

Cellular therapies for chronic ischemic heart failure

The development of stem cell therapies for chronic ischemic heart failure is highly sought after to attempt to improve morbidity and mortality of this prevalent disease. This article reviews clinical trials that investigate stem cell therapy for chronic ischemic heart failure. To generate this review article, PubMed was searched using keywords "stem cell therapy heart failure" with the article type "Clinical Trial" selected on 10/04/2016. The raw search yielded 156 articles; 53 articles were selected for inclusion in the review between the original literature search and manual research/cross-referencing. Additional reviews and original articles were also manually researched and cross-referenced. Cellular-based therapies utilizing peripheral blood progenitor cells, bone marrow cells, mesenchymal stem cells, cells of cardiac origin, and embryonic stem cells have yielded mixed results, but some studies have shown modest efficacy. Skeletal myoblasts raised concerns about safety due to arrhythmias. Optimizing cell type and delivery method will be of critical importance in enhancing efficacy of therapy within various subsets of chronic ischemic heart failure patients. Although much more work needs to be done to optimize treatment strategies, developing stem cell therapies for chronic ischemic heart failure could be of critical importance to lessen the impactful health burden that heart failure has on patients and society.

Adult Stem Cell Therapy for Cardiac Repair in Patients After Acute Myocardial Infarction Leading to Ischemic Heart Failure: An Overview of Evidence from the Recent Clinical Trials

Background:

Cardiovascular diseases (CVD) still represent the leading cause of mortality worldwide, despite the remarkable advances in interventional cardiology, cardiac surgery, and modern pharmacotherapy, particularly in the setting of acute myocardial infarction (AMI), chronic ischemic heart failure (HF), cardiomyopathy (CM), and the associated left ventricular (LV) dysfunction.

A significant loss of cardiomyocytes that underlies all of these conditions was previously considered irreversible. However, current evidence indicates that the human heart has some potential for repair, and over the past decade, many research studies have been exploring the use of stem cells (SCs) to facilitate restoration of myocardium. Consequently, the safety, feasibility, and effectiveness of SC therapy have been reported in many randomized clinical trials (RCTs), using different lineages of adult SCs. Nevertheless, the clinical benefits of SC therapy are not yet well established. In the near future, understanding of the complex interrelations between SCs, paracrine factors, genetic or epigenetic pre-dispositions, and myocardial microenvironment, in the context of an individual patient, will be crucial for translation of this knowledge into practical development of successful, long-term regenerative SC therapeutic applications, in a growing population of patients suffering from previous myocardial in-farction (MI) leading to chronic ischemic cardiomyopathy.

Conclusion:

This overview highlights the therapeutic potential of adult SCs in terms of their possible regenerative capacity, safety, and clinical outcomes, in patients with AMI, and/or subsequent HF (due to chronic ischemic cardiomyopathy). This review was based upon PubMed database search for trials on SC therapy, in patients with AMI and HF, and the main timeframe was set from 2006 to 2016.

Expansion of Umbilical Cord Blood Aldehyde Dehydrogenase Expressing Cells Generates Myeloid Progenitor Cells that Stimulate Limb Revascularization

Uncompromised by chronic disease‐related comorbidities, human umbilical cord blood (UCB) progenitor cells with high aldehyde dehydrogenase activity (ALDH^hi cells) stimulate blood vessel regeneration after intra‐muscular transplantation. However, implementation of cellular therapies using UCB ALDH^hi cells for critical limb ischemia, the most severe form of severe peripheral artery disease, is limited by the rarity (<0.5%) of these cells. Our goal was to generate a clinically‐translatable, allogeneic cell population for vessel regenerative therapies, via ex vivo expansion of UCB ALDH^hi cells without loss of pro‐angiogenic potency. Purified UCB ALDH^hi cells were expanded >18‐fold over 6‐days under serum‐free conditions. Consistent with the concept that ALDH‐activity is decreased as progenitor cells differentiate, only 15.1% ± 1.3% of progeny maintained high ALDH‐activity after culture. However, compared to fresh UCB cells, expansion increased the total number of ALDH^hi cells (2.7‐fold), CD34⁺/CD133⁺ cells (2.8‐fold), and hematopoietic colony forming cells (7.7‐fold). Remarkably, injection of expanded progeny accelerated recovery of perfusion and improved limb usage in immunodeficient mice with femoral artery ligation‐induced limb ischemia. At 7 or 28 days post‐transplantation, mice transplanted with expanded ALDH^hi cells showed augmented endothelial cell proliferation and increased capillary density compared to controls. Expanded cells maintained pro‐angiogenic mRNA expression and secreted angiogenesis‐associated growth factors, chemokines, and matrix modifying proteins. Coculture with expanded cells augmented human microvascular endothelial cell survival and tubule formation under serum‐starved, growth factor‐reduced conditions. Expanded UCB‐derived ALDH^hi cells represent an alternative to autologous bone marrow as an accessible source of pro‐angiogenic hematopoietic progenitor cells for the refinement of vascular regeneration‐inductive therapies. Stem Cells Translational Medicine2017;6:1607–1619

Mitochondrial aldehyde dehydrogenase-2 deficiency compromises therapeutic effect of ALDH bright cell on peripheral ischemia

The autologous ALDH bright (ALDH^br) cell therapy for ischemic injury is clinically safe and effective, while the underlying mechanism remains elusive. Here, we demonstrated that the glycolysis dominant metabolism of ALDH^br cells is permissive to restore blood flow in an ischemic hind limb model compared with bone marrow mononuclear cells (BMNCs). PCR array analysis showed overtly elevated Aldh2 expression of ALDH^br cells following hypoxic challenge. Notably, ALDH^br cells therapy induced blood flow recovery in this model was reduced in case of ALDH2 deficiency. Moreover, significantly reduced glycolysis flux and increased reactive oxygen species (ROS) levels were detected in ALDH^br cell from Aldh2-/- mice. Compromised effect on blood flow recovery was also noticed post transplanting the human ALDH^br cell from ALDH2 deficient patients (GA or AA genotypes) in this ischemic hindlimb mice model. Taken together, our findings illustrate the indispensable role of ALDH2 in maintaining glycolysis dominant metabolism of ALDH^br cell and advocate that patient's Aldh2 genotype is a prerequisite for the efficacy of ALDH^br cell therapy for peripheral ischemia.

Left ventricular perforation in a patient with a left ventricular aneurysm during NOGA® catheter mapping

Endocardial mapping of the left ventricle (LV) using the NOGA® XP Cardiac Navigation System can identify chronically ischemic and viable myocardium in patients with coronary artery disease by generating electromechanical maps. These maps are very useful when targeting myocardial tissue for injection of stem cells. We present the case of a woman who developed a perforation at the site of an LV aneurysm during NOGA mapping prior to the transendocardial injection of stem cells, as part of a multicenter clinical trial. The presence of an LV aneurysm is currently not a contraindication (or caution) to the use the NOGA mapping catheter. As the field of stem cell therapy evolves and the use of this technique increases, operators must be aware that the presence of an LV aneurysm may increase the risk of perforation during a NOGA mapping procedure.

Single cell biology beyond the era of antibodies: relevance, challenges, and promises in biomedical research

Research of the past two decades has proved the relevance of single cell biology in basic research and translational medicine. Successful detection and isolation of specific subsets is the key to understand their functional heterogeneity. Antibodies are conventionally used for this purpose, but their relevance in certain contexts is limited. In this review, we discuss some of these contexts, posing bottle neck for different fields of biology including biomedical research. With the advancement of chemistry, several methods have been introduced to overcome these problems. Even though microfluidics and microraft array are newer techniques exploited for single cell biology, fluorescence-activated cell sorting (FACS) remains the gold standard technique for isolation of cells for many biomedical applications, like stem cell therapy. Here, we present a comprehensive and comparative account of some of the probes that are useful in FACS. Further, we illustrate how these techniques could be applied in biomedical research. It is postulated that intracellular molecular markers like nucleostemin (GNL3), alkaline phosphatase (ALPL) and HIRA can be used for improving the outcome of cardiac as well as bone regeneration. Another field that could utilize intracellular markers is diagnostics, and we propose the use of specific peptide nucleic acid probes (PNPs) against certain miRNAs for cancer surgical margin prediction. The newer techniques for single cell biology, based on intracellular molecules, will immensely enhance the repertoire of possible markers for the isolation of cell types useful in biomedical research.

Delivery of drugs, growth factors, genes and stem cells via intrapericardial, epicardial and intramyocardial routes for sustained local targeted therapy of myocardial disease

INTRODUCTION

Local myocardial delivery (LMD) of therapeutic agents is a promising strategy that aims to treat various myocardial pathologies. It is designed to deliver agents directly to the myocardium and minimize their extracardiac concentrations and side effects. LMD aims to enhance outcomes of existing therapies by broadening their therapeutic window and to utilize new agents that could not be otherwise be implemented systemically. Areas covered: This article provides a historical overview of six decades LMD evolution in terms of the approaches, including intrapericardial, epicardial, and intramyocardial delivery, and the wide array of classes of agents used to treat myocardial pathologies. We examines delivery of pharmaceutical compounds, targeted gene transfection and cell implantation techniques to produce therapeutic effects locally. We outline therapeutic indications, successes and failures as well as technical approaches for LMD. Expert opinion: While LMD is more complicated than conventional oral or intravenous administration, given recent advances in interventional cardiology, it is safe and may provide better therapeutic outcomes. LMD is complex as many factors impact pharmacokinetics and biologic result. The choice between routes of LMD is largely driven not only by the myocardial pathology but also by the nature and physicochemical properties of the therapeutic agents.

Evaluation of Cell Therapy on Exercise Performance and Limb Perfusion in Peripheral Artery Disease: The CCTRN PACE Trial (Patients With Intermittent Claudication Injected With ALDH Bright Cells)

BACKGROUND

Atherosclerotic peripheral artery disease affects 8% to 12% of Americans >65 years of age and is associated with a major decline in functional status, increased myocardial infarction and stroke rates, and increased risk of ischemic amputation. Current treatment strategies for claudication have limitations. PACE (Patients With Intermittent Claudication Injected With ALDH Bright Cells) is a National Heart, Lung, and Blood Institute-sponsored, randomized, double-blind, placebo-controlled, phase 2 exploratory clinical trial designed to assess the safety and efficacy of autologous bone marrow-derived aldehyde dehydrogenase bright (ALDHbr) cells in patients with peripheral artery disease and to explore associated claudication physiological mechanisms.

METHODS

All participants, randomized 1:1 to receive ALDHbr cells or placebo, underwent bone marrow aspiration and isolation of ALDHbr cells, followed by 10 injections into the thigh and calf of the index leg. The coprimary end points were change from baseline to 6 months in peak walking time (PWT), collateral count, peak hyperemic popliteal flow, and capillary perfusion measured by magnetic resonance imaging, as well as safety.

RESULTS

A total of 82 patients with claudication and infrainguinal peripheral artery disease were randomized at 9 sites, of whom 78 had analyzable data (57 male, 21 female patients; mean age, 66±9 years). The mean±SEM differences in the change over 6 months between study groups for PWT (0.9±0.8 minutes; 95% confidence interval [CI] -0.6 to 2.5; P=0.238), collateral count (0.9±0.6 arteries; 95% CI, -0.2 to 2.1; P=0.116), peak hyperemic popliteal flow (0.0±0.4 mL/s; 95% CI, -0.8 to 0.8; P=0.978), and capillary perfusion (-0.2±0.6%; 95% CI, -1.3 to 0.9; P=0.752) were not significant. In addition, there were no significant differences for the secondary end points, including quality-of-life measures. There were no adverse safety outcomes. Correlative relationships between magnetic resonance imaging measures and PWT were not significant. A post hoc exploratory analysis suggested that ALDHbr cell administration might be associated with an increase in the number of collateral arteries (1.5±0.7; 95% CI, 0.1-2.9; P=0.047) in participants with completely occluded femoral arteries.

CONCLUSIONS

ALDHbr cell administration did not improve PWT or magnetic resonance outcomes, and the changes in PWT were not associated with the anatomic or physiological magnetic resonance imaging end points. Future peripheral artery disease cell therapy investigational trial design may be informed by new anatomic and perfusion insights.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT01774097.

Stem cell therapy for chronic ischaemic heart disease and congestive heart failure

BACKGROUND

A promising approach to the treatment of chronic ischaemic heart disease and congestive heart failure is the use of stem cells. The last decade has seen a plethora of randomised controlled trials developed worldwide, which have generated conflicting results.

OBJECTIVES

The critical evaluation of clinical evidence on the safety and efficacy of autologous adult bone marrow-derived stem/progenitor cells as a treatment for chronic ischaemic heart disease and congestive heart failure.

SEARCH METHODS

We searched CENTRAL in the Cochrane Library, MEDLINE, Embase, CINAHL, LILACS, and four ongoing trial databases for relevant trials up to 14 December 2015.

SELECTION CRITERIA

Eligible studies were randomised controlled trials comparing autologous adult stem/progenitor cells with no cells in people with chronic ischaemic heart disease and congestive heart failure. We included co-interventions, such as primary angioplasty, surgery, or administration of stem cell mobilising agents, when administered to treatment and control arms equally.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened all references for eligibility, assessed trial quality, and extracted data. We undertook a quantitative evaluation of data using random-effects meta-analyses. We evaluated heterogeneity using the I2 statistic and explored substantial heterogeneity (I2 greater than 50%) through subgroup analyses. We assessed the quality of the evidence using the GRADE approach. We created a 'Summary of findings' table using GRADEprofiler (GRADEpro), excluding studies with a high or unclear risk of selection bias. We focused our summary of findings on long-term follow-up of mortality, morbidity outcomes, and left ventricular ejection fraction measured by magnetic resonance imaging.

MAIN RESULTS

We included 38 randomised controlled trials involving 1907 participants (1114 cell therapy, 793 controls) in this review update. Twenty-three trials were at high or unclear risk of selection bias. Other sources of potential bias included lack of blinding of participants (12 trials) and full or partial commercial sponsorship (13 trials).Cell therapy reduced the incidence of long-term mortality (≥ 12 months) (risk ratio (RR) 0.42, 95% confidence interval (CI) 0.21 to 0.87; participants = 491; studies = 9; I2 = 0%; low-quality evidence). Periprocedural adverse events associated with the mapping or cell/placebo injection procedure were infrequent. Cell therapy was also associated with a long-term reduction in the incidence of non-fatal myocardial infarction (RR 0.38, 95% CI 0.15 to 0.97; participants = 345; studies = 5; I2 = 0%; low-quality evidence) and incidence of arrhythmias (RR 0.42, 95% CI 0.18 to 0.99; participants = 82; studies = 1; low-quality evidence). However, we found no evidence that cell therapy affects the risk of rehospitalisation for heart failure (RR 0.63, 95% CI 0.36 to 1.09; participants = 375; studies = 6; I2 = 0%; low-quality evidence) or composite incidence of mortality, non-fatal myocardial infarction, and/or rehospitalisation for heart failure (RR 0.64, 95% CI 0.38 to 1.08; participants = 141; studies = 3; I2 = 0%; low-quality evidence), or long-term left ventricular ejection fraction when measured by magnetic resonance imaging (mean difference -1.60, 95% CI -8.70 to 5.50; participants = 25; studies = 1; low-quality evidence).

AUTHORS' CONCLUSIONS

This systematic review and meta-analysis found low-quality evidence that treatment with bone marrow-derived stem/progenitor cells reduces mortality and improves left ventricular ejection fraction over short- and long-term follow-up and may reduce the incidence of non-fatal myocardial infarction and improve New York Heart Association (NYHA) Functional Classification in people with chronic ischaemic heart disease and congestive heart failure. These findings should be interpreted with caution, as event rates were generally low, leading to a lack of precision.

Cellular Therapy for Heart Failure

The pathogenesis of cardiomyopathy and heart failure (HF) is underpinned by complex changes at subcellular, cellular and extracellular levels in the ventricular myocardium. For all of the gains that conventional treatments for HF have brought to mortality and morbidity, they do not adequately address the loss of cardiomyocyte numbers in the remodeling ventricle. Originally conceived to address this problem, cellular transplantation for HF has already gone through several stages of evolution over the past two decades. Various cell types and delivery routes have been implemented to positive effect in preclinical models of ischemic and nonischemic cardiomyopathy, with pleiotropic benefits observed in terms of myocardial remodeling, systolic and diastolic performance, perfusion, fibrosis, inflammation, metabolism and electrophysiology. To a large extent, these salubrious effects are now attributed to the indirect, paracrine capacity of transplanted stem cells to facilitate endogenous cardiac repair processes. Promising results have also followed in early phase human studies, although these have been relatively modest and somewhat inconsistent. This review details the preclinical and clinical evidence currently available regarding the use of pluripotent stem cells and adult-derived progenitor cells for cardiomyopathy and HF. It outlines the important lessons that have been learned to this point in time, and balances the promise of this exciting field against the key challenges and questions that still need to be addressed at all levels of research, to ensure that cell therapy realizes its full potential by adding to the armamentarium of HF management.

Advances in stem cell therapy for cardiovascular disease (Review)

Cardiovascular disease constitutes the primary cause of mortality and morbidity worldwide, and represents a group of disorders associated with the loss of cardiac function. Despite considerable advances in the understanding of the pathologic mechanisms of the disease, the majority of the currently available therapies remain at best palliative, since the problem of cardiac tissue loss has not yet been addressed. Indeed, few therapeutic approaches offer direct tissue repair and regeneration, whereas the majority of treatment options aim to limit scar formation and adverse remodeling, while improving myocardial function. Of all the existing therapeutic approaches, the problem of cardiac tissue loss is addressed uniquely by heart transplantation. Nevertheless, alternative options, particularly stem cell therapy, has emerged as a novel and promising approach. This approach involves the transplantation of healthy and functional cells to promote the renewal of damaged cells and repair injured tissue. Bone marrow precursor cells were the first cell type used in clinical studies, and subsequently, preclinical and clinical investigations have been extended to the use of various populations of stem cells. This review addresses the present state of research as regards stem cell therapy for cardiovascular disease.

Impact of Cell Therapy on Myocardial Perfusion and Cardiovascular Outcomes in Patients With Angina Refractory to Medical Therapy: A Systematic Review and Meta-Analysis

RATIONALE

The effect of stem/progenitor cells on myocardial perfusion and clinical outcomes in patients with refractory angina remains unclear because studies published to date have been small phase I-II trials.

OBJECTIVE

We performed a meta-analysis of randomized controlled trials to evaluate the effect of cell-based therapy in patients with refractory angina who were ineligible for coronary revascularization.

METHODS AND RESULTS

Several data sources were searched from inception to September 2015, which yielded 6 studies. The outcomes pooled were indices of angina (anginal episodes, Canadian Cardiovascular Society angina class, exercise tolerance, and antianginal medications), myocardial perfusion, and clinical end points. We combined the reported clinical outcomes (myocardial infarction, cardiac-related hospitalization, and mortality) into a composite end point (major adverse cardiac events). Mean difference (MD), standardized mean differences, or odds ratio were calculated to assess relevant outcomes. Our analysis shows an improvement in anginal episodes (MD, -7.81; 95% confidence interval [CI], -15.22 to -0.41), use of antianginal medications (standardized MD, -0.59; 95% CI, -1.03 to -0.14), Canadian Cardiovascular Society class (MD, -0.58; 95% CI, -1.00 to -0.16), exercise tolerance (standardized MD, 0.331; 95% CI, 0.08 to 0.55), and myocardial perfusion (standardized MD, -0.49; 95% CI, -0.76 to -0.21) and a decreased risk of major adverse cardiac events (odds ratio, 0.49; 95% CI, 0.25 to 0.98) and arrhythmias (odds ratio, 0.25; 95% CI, 0.06 to 0.98) in cell-treated patients when compared with patients on maximal medical therapy.

CONCLUSIONS

The present meta-analysis indicates that cell-based therapies are not only safe but also lead to an improvement in indices of angina, relevant clinical outcomes, and myocardial perfusion in patients with refractory angina. These encouraging results suggest that larger, phase III randomized controlled trials are in order to conclusively determine the effect of stem/progenitor cells in refractory angina.

Stem cell therapy for chronic heart failure

PURPOSE OF REVIEW

The aim of this review was to discuss recent advances in clinical aspects of stem cell therapy in heart failure with emphasis on patient selection, stem cell types and delivery methods.

RECENT FINDINGS

Several stem cell types have been considered for the treatment of patients with heart failure. In nonischemic heart failure, transplantation of CD34 cells improved myocardial performance, functional capacity and neurohumoral activation. In ischemic heart failure, cardiosphere-derived cells were shown to reduce myocardial scar burden with concomitant increase in viable tissue and regional systolic wall thickening. Both autologous and allogeneic mesenchymal stem cells were shown to be effective in improving heart function in patients with ischemic heart failure; this may represent an important step toward the development of a standardized stem cell product for widespread clinical use.

SUMMARY

Although trials of stem cell therapy in heart failure have shown promising results, the findings are not consistent. Given the wide spectrum of heart failure, it may be difficult to define a uniform stem cell therapy for all subsets of patients; instead, future stem cell therapeutic strategies should aim for a more personalized approach by establishing optimal stem cell type, dose and delivery method for an individual patient and disease state.

Nanotechnology for mesenchymal stem cell therapies

Mesenchymal stem cells (MSC) display great proliferative, differentiative, chemotactic, and immune-modulatory properties required to promote tissue repair. Several clinical trials based on the use of MSC are currently underway for therapeutic purposes. The aim of this article is to examine the current trends and potential impact of nanotechnology in MSC-driven regenerative medicine. Nanoparticle-based approaches are used as powerful carrier systems for the targeted delivery of bioactive molecules to ensure MSC long-term maintenance in vitro and to enhance their regenerative potential. Nanostructured materials have been developed to recapitulate the stem cell niche within a tissue and to instruct MSC toward the creation of regeneration-permissive environment. Finally, the capability of MSC to migrate toward the site of injury/inflammation has allowed for the development of diagnostic imaging systems able to monitor transplanted stem cell bio-distribution, toxicity, and therapeutic effectiveness.

Concise Review: Review and Perspective of Cell Dosage and Routes of Administration From Preclinical and Clinical Studies of Stem Cell Therapy for Heart Disease

An important stage in the development of any new therapeutic agent is establishment of the optimal dosage and route of administration. Inconsistent findings have been reported regarding the relationship between the cell dose and clinical benefit. The present study summarizes the data regarding the optimal cell dosage and route of administration from studies of stem cell therapy for heart disease and offers a perspective on future directions.

An important stage in the development of any new therapeutic agent is establishment of the optimal dosage and route of administration. This can be particularly challenging when the treatment is a biologic agent that might exert its therapeutic effects via complex or poorly understood mechanisms. Multiple preclinical and clinical studies have shown paradoxical results, with inconsistent findings regarding the relationship between the cell dose and clinical benefit. Such phenomena can, at least in part, be attributed to variations in cell dosing or concentration and the route of administration (ROA). Although clinical trials of cell-based therapy for cardiovascular disease began more than a decade ago, specification of the optimal dosage and ROA has not been established. The present review summarizes what has been learned regarding the optimal cell dosage and ROA from preclinical and clinical studies of stem cell therapy for heart disease and offers a perspective on future directions.

Significance

Preclinical and clinical studies on cell-based therapy for cardiovascular disease have shown inconsistent results, in part because of variations in study-specific dosages and/or routes of administration (ROA). Future preclinical studies and smaller clinical trials implementing cell-dose and ROA comparisons are warranted before proceeding to pivotal trials.

Adult Bone Marrow Cell Therapy for Ischemic Heart Disease: Evidence and Insights From Randomized Controlled Trials

RATIONALE

Notwithstanding the uncertainties about the outcomes of bone marrow cell (BMC) therapy for heart repair, further insights are critically needed to improve this promising approach.

OBJECTIVE

To delineate the true effect of BMC therapy for cardiac repair and gain insights for future trials through systematic review and meta-analysis of data from eligible randomized controlled trials.

METHODS AND RESULTS

Database searches through August 2014 identified 48 eligible randomized controlled trials (enrolling 2602 patients). Weighted mean differences for changes in left ventricular (LV) ejection fraction, infarct size, LV end-systolic volume, and LV end-diastolic volume were analyzed with random-effects meta-analysis. Compared with standard therapy, BMC transplantation improved LV ejection fraction (2.92%; 95% confidence interval, 1.91-3.92; P<0.00001), reduced infarct size (-2.25%; 95% confidence interval, -3.55 to -0.95; P=0.0007) and LV end-systolic volume (-6.37 mL; 95% confidence interval, -8.95 to -3.80; P<0.00001), and tended to reduce LV end-diastolic volume (-2.26 mL; 95% confidence interval, -4.59 to 0.07; P=0.06). Similar effects were noted when data were analyzed after excluding studies with discrepancies in reporting of outcomes. The benefits also persisted when cardiac catheterization was performed in control patients as well. Although imaging modalities partly influenced the outcomes, LV ejection fraction improved in BMC-treated patients when assessed by magnetic resonance imaging. Early (<48 hours) BMC injection after myocardial Infarction was more effective in reducing infarct size, whereas BMC injection between 3 and 10 days proved superior toward improving systolic function. A minimum of 50 million BMCs seemed to be necessary, with limited additional benefits seen with increasing cell numbers. BMC therapy was safe and improved clinical outcomes, including all-cause mortality, recurrent myocardial Infarction, ventricular arrhythmia, and cerebrovascular accident during follow-up, albeit with differences between acute myocardial Infarction and chronic ischemic heart disease subgroups.

CONCLUSIONS

Transplantation of adult BMCs improves LV ejection fraction, reduces infarct size, and ameliorates remodeling in patients with ischemic heart disease. These effects are upheld in the analyses of studies using magnetic resonance imaging and also after excluding studies with discrepant reporting of outcomes. BMC transplantation may also reduce the incidence of death, recurrent myocardial Infarction, ventricular arrhythmia, and cerebrovascular accident during follow-up.

Intramyocardial Autologous Bone Marrow-derived Stem Cells Injection for Ischemic Heart Disease Ineligible for Revascularization: A Systematic Review and Meta-analysis

BACKGROUND AND AIMS

Intramyocardial autologous bone marrow-derived stem cells injection (IM-BMCs) has been used in patients with ischemic heart disease (IHD) who are ineligible for revascularization; however, the procedure has yielded mixed results. The objective of this meta-analysis was to evaluate the safety and therapeutic benefits of this treatment on a relatively large scale.

METHODS

PubMed, EMBASE, and Cochrane Library databases through September 2014 were searched for randomized clinical trials (RCTs) of IM-BMCs to treat IHD. Outcome measures were defined as mortality after treatment, change in left ventricular ejection fraction (LVEF), left ventricular end-systolic volume (LVESV) and left ventricular end-diastolic volume (LVEDV). Weighted mean differences for the changes were estimated with a random-effects model.

RESULTS

Nine RCTs were eligible for inclusion. IM-BMCs significantly reduced the risk of mortality (RR, 0.33; 95% CI, 0.17-0.65; p = 0.001). IM-BMCs significantly improved LVEF by 2.57% (95% CI, 0.34-4.80%; p = 0.02) and reduced LVESV by 9.67 mL (95% CI, -16.43 mL to -2.91 mL; p = 0.005). No significant improvement in LVEDV (WMD = 4.73 mL; 95% CI, -7.22 mL to 16.68 mL; p = 0.44) was detected in patients who received IM-BMC therapy.

CONCLUSIONS

IM-BMC therapy showed clinical safety while being used as stand-alone treatment in IHD with no option of revascularization. The therapeutic efficacy requires further confirmation in large well-powered trials with long-term follow-up.

Sca-1+ cells from fetal heart with high aldehyde dehydrogenase activity exhibit enhanced gene expression for self-renewal, proliferation, and survival

Stem/progenitor cells from multiple tissues have been isolated based on enhanced activity of cytosolic aldehyde dehydrogenase (ALDH) enzyme. ALDH activity has emerged as a reliable marker for stem/progenitor cells, such that ALDH^bright/high cells from multiple tissues have been shown to possess enhanced stemness properties (self-renewal and multipotency). So far though, not much is known about ALDH activity in specific fetal organs. In this study, we sought to analyze the presence and activity of the ALDH enzyme in the stem cell antigen-1-positive (Sca-1+) cells of fetal human heart. Biochemical assays showed that a subpopulation of Sca-1+ cells (15%) possess significantly high ALDH1 activity. This subpopulation showed increased expression of self-renewal markers compared to the ALDH^low fraction. The ALDH^high fraction also exhibited significant increase in proliferation and pro-survival gene expression. In addition, only the ALDH^high and not the ALDH^low fraction could give rise to all the cell types of the original population, demonstrating multipotency. ALDH^high cells showed increased resistance against aldehyde challenge compared to ALDH^low cells. These results indicate that ALDH^high subpopulation of the cultured human fetal cells has enhanced self-renewal, multipotency, high proliferation, and survival, indicating that this might represent a primitive stem cell population within the fetal human heart.

Stem cells in the management of heart failure: what have we learned from clinical trials?

Research shows that various types of stem cells (SCs) have the ability to rebuild damaged heart tissue. The TIME and Late TIME human trials shed light on the optimum timing of SC therapy administration after myocardial damage. The FOCUS study failed to show a substantial positive effect of bone marrow-derived mononuclear cells in patients suffering from ischemic heart failure; however, some completed human trials do show promise, with improvement in cardiac function. Recent clinical trials have identified a subset of marrow cells that was able to stimulate endogenous adult cardiac SCs where cardiac SCs administration showed promise in the SCIPIO trial. This review addresses some of the lessons learned from clinical trials with SC therapy in ischemic heart failure.

Rationale and design for PACE: patients with intermittent claudication injected with ALDH bright cells

Peripheral artery disease (PAD) is recognized as a public health issue because of its prevalence, functional limitations, and increased risk of systemic ischemic events. Current treatments for claudication, the primary symptom in patients with PAD, have limitations. Cells identified using cytosolic enzyme aldehyde dehydrogenase (ALDH) may benefit patients with severe PAD but has not been studied in patients with claudication. PACE is a randomized, double-blind, placebo-controlled clinical trial conducted by the Cardiovascular Cell Therapy Research Network to assess the safety and efficacy of autologous bone marrow-derived ALDH(br) cells delivered by direct intramuscular injections in 80 patients with symptom-limiting intermittent claudication. Eligible patients will have a significant stenosis or occlusion of infrainguinal arteries and a resting ankle-brachial index less than 0.90 and will be randomized 1:1 to cell or placebo treatment with a 1-year follow-up. The primary end points are the change in peak walking time and leg collateral arterial anatomy, calf muscle blood flow, and tissue perfusion as determined by magnetic resonance imaging at 6 months compared with baseline. The latter 3 measurements are new physiologic lower extremity tissue perfusion and PAD imaging-based end points that may help to quantify the biologic and mechanistic effects of cell therapy. This trial will collect important mechanistic and clinical information on the safety and efficacy of ALDH(br) cells in patients with claudication and provide valuable insight into the utility of advanced magnetic resonance imaging end points.