Human iPSC-derived Committed Cardiac Progenitors Generate Cardiac Tissue Grafts in a Swine Ischemic Cardiomyopathy Model without Triggering Ventricular Arrhythmias

BackgroundIntramyocardial injection of human pluripotent stem cell-derived cardiomyocytes following a myocardial infarction (MI) improves cardiac function in large animal models, but associated ventricular arrhythmias are major safety concern. We hypothesized that transendocardial injection of human induced pluripotent stem cell (hiPSC)-derived committed cardiac progenitor cells (CCPs), combined with cardiac fibroblast-derived extracellular matrix (cECM) to enhance cell retention, will generate cardiac tissue grafts improving contractility without triggering ventricular arrhythmias. MethodshiPSCs were differentiated using bioreactors and small molecules to produce committed cardiac progenitor cells (CCPs). MI was created using a coronary artery balloon occlusion and reperfusion model in Yucatan mini pigs. Four weeks later, epicardial needle injections of CCPs+cECM were performed in a small initial feasibility cohort (n=6), and then transendocardial injections of CCPs+cECM (n=14), CCPs alone (n=14), cECM alone (n=4) or vehicle control (n=13) into the peri-infarct region in a randomized cohort. Arrhythmias were evaluated using implanted event recorders. Magnetic resonance imaging (MRI) and invasive pressure-volume assessment were used to evaluate left ventricular anatomic and functional performance. Detailed histology was performed to detect and characterize human grafts. ResultsA scalable biomanufacturing protocol was developed generating CCPs which can efficiently differentiate into cardiomyocytes or endothelial cells in vitro. Intramyocardial delivery of CCPs to post-MI porcine hearts resulted in engraftment and differentiation of CCPs to form ventricular cardiomyocyte rich grafts. There was no significant difference in cardiac MRI-based measured cardiac volumes or function between control, CCP and CCP+cECM groups; however, pressure-volume analysis showed an improvement in dobutamine-stimulated functional reserve in CCP and CCP+cECM groups. Delivery of CCPs did not result in tumors or ventricular arrhythmias. ConclusionsTransendocardial delivery of CCPs with or without cECM into post-MI porcine hearts resulted in comparable human cardiomyocyte grafts which did not improve resting LV function but did improve stress-induced contractile reserve without triggering ventricular arrhythmias.