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.

Intracoronary and retrograde coronary venous myocardial delivery of adipose-derived stem cells in swine infarction lead to transient myocardial trapping with predominant pulmonary redistribution.

OBJECTIVES: To examine the comparative fate of adipose-derived stem cells (ASCs) as well as their impact on coronary microcirculation following either retrograde coronary venous (RCV) or arterial delivery. BACKGROUND: Local delivery of ASCs to the heart has been proposed as a practical approach to limiting the extent of myocardial infarction. Mouse models of mesenchymal stem cell effects on the heart have also demonstrated significant benefits from systemic (intravenous) delivery, prompting a question about the advantage of local delivery. There has been no study addressing the extent of myocardial vs. systemic disposition of ASCs in large animal models following local delivery to the myocardium. METHODS: In an initial experiment, dose-dependent effects of ASC delivery on coronary circulation in normal swine were evaluated to establish a tolerable ASC dosing range for intracoronary (IC) delivery. In a set of subsequent experiments, an anterior acute myocardial infarction (AMI) was created by balloon occlusion of the proximal left anterior descending (LAD) artery, followed by either IC or RCV infusion of 10(7) (111)Indium-labeled autologous ASCs 6 days following AMI. Indices of microcirculatory resistance (IMR) and coronary flow reserve (CFR) were measured before sacrifices to collect tissues for analysis at 1 or 24 hr after cell delivery. RESULTS: IC delivery of porcine ASCs to normal myocardium was well tolerated up to a cumulative dose of 14 × 10(6) cells (approximately 0.5 × 10(6) cells/kg). There was evidence suggesting microcirculatory trapping of ASC: at unit doses of 50 × 10(6) ASCs, IMR and CFR were found to be persistently altered in the target LAD distribution at 7 days following delivery, whereas at 10 × 10(6) ASCs, only CFR was altered. In the context of recent MI, a significantly higher percentage of ASCs was retained at 1 hr with IC delivery compared with RCV delivery (57.2 ± 12.7% vs. 17.9 ± 1.6%, P = 0.037) but this initial difference was not apparent at 24 hr (22.6 ± 5.5% vs. 18.7 ± 8.6%; P = 0.722). In both approaches, most ASC redistributed to the pulmonary circulation by 24 hr postdelivery. There were no significant differences in CFR or IMR following ASC delivery to infarcted tissue by either route. CONCLUSIONS: Selective intravascular delivery of ASC by coronary arterial and venous routes leads to similarly limited myocardial cell retention with predominant redistribution of cells to the lungs. IC arterial delivery of ASC leads to only transiently greater myocardial retention, which is accompanied by obstruction of normal regions of coronary microcirculation at higher doses. The predominant intrapulmonary localization of cells following local delivery via both methods prompts the notion that systemic delivery of ASC might provide similarly beneficial outcomes while avoiding risks of inadvertent microcirculatory compromise.

Ex vivo intracoronary gene transfer of adeno-associated virus 2 leads to superior transduction over serotypes 8 and 9 in rat heart transplants.

Heart transplant gene therapy requires vectors with long-lasting gene expression, high cardiotropism, and minimal pathological effects. Here, we examined transduction properties of ex vivo intracoronary delivery of adeno-associated virus (AAV) serotype 2, 8, and 9 in rat syngenic and allogenic heart transplants. Adult Dark Agouti (DA) rat hearts were intracoronarily perfused ex vivo with AAV2, AAV8, or AAV9 encoding firefly luciferase and transplanted heterotopically into the abdomen of syngenic DA or allogenic Wistar-Furth (WF) recipients. Serial in vivo bioluminescent imaging of syngraft and allograft recipients was performed for 6 months and 4 weeks, respectively. Grafts were removed for PCR-, RT-PCR, and luminometer analysis. In vivo bioluminescent imaging of recipients showed that AAV9 induced a prominent and stable luciferase activity in the abdomen, when compared with AAV2 and AAV8. However, ex vivo analyses revealed that intracoronary perfusion with AAV2 resulted in the highest heart transplant transduction levels in syngrafts and allografts. Ex vivo intracoronary delivery of AAV2 resulted in efficient transgene expression in heart transplants, whereas intracoronary AAV9 escapes into adjacent tissues. In terms of cardiac transduction, these results suggest AAV2 as a potential vector for gene therapy in preclinical heart transplants studies, and highlight the importance of delivery route in gene transfer studies.

Mitochondrial Transplantation for Ischemia Reperfusion Injury.

Mitochondrial transplantation is a novel therapeutic intervention to treat ischemia-reperfusion-related disorders. This approach uses replacement of native mitochondria with viable, respiration-competent mitochondria isolated from non-ischemic tissue obtained from the patient's own body, to overcome the many deleterious effects of ischemia-reperfusion injury on native mitochondria. The safety and efficacy of this methodology has been demonstrated in cell culture, animal models and has been shown to be safe and efficacious in a phase I clinical trial in pediatric cardiac patients with ischemia-reperfusion injury. These studies have demonstrated that mitochondrial transplantation rescues myocardial cellular viability and significantly enhances postischemic myocardial function following ischemia-reperfusion injury. Herein, we describe methodologies for the delivery of isolated mitochondria.

Safety and efficacy of global intracoronary administration of cardiosphere-derived cells or conditioned medium immediately after coronary reperfusion in rats.

OBJECTIVE: Cardiosphere-derived cells (CDCs) have been shown to reduce infarct size after myocardial infarction (MI). In the present study we investigated the safety and efficacy of global intracoronary administration (GIA) of CDCs or CDC-conditioned medium (CM) immediately after reperfusion in a rat model of ischemia-reperfusion. METHODS: CDCs were grown from myocardial biopsies obtained from male Wistar Kyoto rats (WKY). Female WKY rats underwent MI for 45minutes, followed by reperfusion for 1hour. Infarcted rats were randomized to receive GIA of CDCs (CDC group), CM (CM group) or vehicle (control group) immediately after the onset of reperfusion. Cell retention was quantified by PCR for the male specific SRY gene; area at risk (AR) and no reflow area (NR) were measured by histopathology. Cardiac function was evaluated by echocardiography at 1 and 2 months post-MI. RESULTS: Cell retention at 1hour after GIA was 25.1% ±5.1. The myocardial AR and NR (measured at 1 hour post-reperfusion) were similar between groups [AR: 28.8% ±7.4 of LV mass in control vs 27.2% ±8 in CM vs 27% ±7 in CDCs group. NR: 7.0% ±3.3 in control vs 7.3% ±3.8 in CM vs 7.1% ±3.6 in CDCs]. One and 2 months post-MI, systolic function and LV volumes did not differ between control and CM groups. CONCLUSION: Intracoronary administration of CDCs during the acute phase of MI, at the beginning of reperfusion, does not aggravate microvascular obstruction and results in high cell retention. Delivery of CM in the acute phase of MI did not confer long-term cardiac functional benefits.

Intracoronary sarcoplasmic reticulum calcium-atpase gene therapy in advanced heart failure patients with reduced ejection fraction: a prospective cohort study

OBJECTIVE: Heart failure is a progressive and debilitating disease. Intracoronary sarcoplasmic reticulum calcium-ATPase gene therapy may improve the function of cardiac muscle cells. This study aimed to test the hypothesis that intracoronary sarcoplasmic reticulum calcium-ATPase gene therapy can improve outcomes and reduce the number of recurrent and terminal events in advanced heart failure patients with reduced ejection fraction. METHODS: A total of 768 heart failure patients with reduced ejection fraction and New York Heart Association classification II to IV were included in this prospective cohort study. Patients either underwent intracoronary sarcoplasmic reticulum calcium-ATPase gene therapy (CA group, n=384) or received oral placebo (PA group; n=384). Data regarding recurrent and terminal event(s), treatment-emergent adverse effects, and outcome measures were collected and analyzed. RESULTS: After a follow-up period of 18 months, intracoronary sarcoplasmic reticulum calcium-ATPase gene therapy reduced the number of hospital admissions (p=0.001), ambulatory treatments (p=0.0004), and deaths (p=0.024). Additionally, intracoronary sarcoplasmic reticulum calcium-ATPase gene therapy improved the left ventricular ejection fraction (p<0.0001) and Kansas City Cardiomyopathy Questionnaire score (p<0.0001). The number of recurrent and terminal events/patients were higher in the PA group than in the CA group after the follow-up period of 18 months (p=0.015). The effect of the intracoronary sarcoplasmic reticulum calcium-ATPase gene therapy was independent of the confounding variables. No new arrhythmias were reported in the CA group. CONCLUSIONS: Intracoronary sarcoplasmic reticulum calcium-ATPase gene therapy reduces the number of recurrent and terminal events and improves the clinical course of advanced heart failure patients with reduced ejection fraction.

Safety and feasibility of intramyocardial versus intracoronary delivery of autologous cell therapy in advanced heart failure: the REGENERATE-IHD pilot study.

AIM: This study presents an interim safety and feasibility analysis of the REGENERATE-IHD randomized controlled trial, which is examining the safety and efficacy of three different delivery routes of bone marrow-derived stem cells (BMSCs) in patients with ischemic heart failure. METHODS & RESULTS: The first 58 patients recruited to the REGENERATE-IHD study are included in this interim analysis (pilot). Symptomatic patients with ischemic heart failure were randomized to receive subcutaneous granulocyte colony-stimulating factor or saline injections only; or subcutaneous granulocyte colony-stimulating factor injections followed by intracoronary or intramyocardial injections of BMSCs or serum (control). No significant differences were found in terms of safety and feasibility between the different delivery routes, with no significant difference in procedural complications or major adverse cardiac events. There was a signal towards improved heart failure symptoms in the patients treated with intramyocardial injection of mobilized BMSCs. CONCLUSION: Peripheral mobilization of BMSCs with or without subsequent direct myocardial delivery appears safe and feasible in patients with chronic ischemic heart failure.