Abstract 11714: Allogeneic Cardiosphere-Derived Cells Administered at the Time of Reperfusion Only Improve Ejection Fraction When Infused to Ischemic as well as Remote Myocardial Regions in Swine With Acute Myocardial Infarction

Abstract

Introduction: While intracoronary infusion of cardiosphere-derived cells (CDCs) to myocardial infarcts using the stop-flow technique reduces scar volume, ejection fraction (EF) remains unchanged. Hypothesis: We hypothesized that this may relate to ineffective treatment of myocyte loss in normally-perfused remote regions which could negatively impact EF. We therefore compared CDC infusion to the entire heart with conventional regional infusion to the infarct-related artery. Methods: Swine (n=24) chronically treated with cyclosporine (100 mg/day) underwent a 1-hour LAD occlusion and EF decreased from 60 ± 2% at baseline to 46 ± 2% after reperfusion (p<0.05 vs. baseline). We infused either 10x10^6 intracoronary allogeneic CDCs via stop-flow infusion (regional LAD infusion), 20x10^6 intracoronary allogeneic CDCs to the entire heart under flow (global infusion) or vehicle 30 minutes after reperfusion. Four weeks later we assessed left ventricular function (echo), myocyte proliferation (Ki67), infarct size (TTC), myocyte nuclear density and cell size. Data were compared to vehicle. Results: Regional LAD infusion increased wall thickening and reduced scar volume but did not affect EF (Table). In contrast, global infusion increased EF despite an insignificant reduction in infarct volume. This was accompanied by 2-fold increases in myocyte proliferation (Ki67) in border and remote regions which did not change with regional LAD infusion. Global infusion increased myocyte nuclear density by 12% and decreased cell size by 9% while there were no significant changes after regional LAD infusion. Conclusion: Although regional LAD infusion reduces scar size and improves regional function, only global infusion improves EF since it effectively stimulates endogenous myocyte regeneration throughout the entire left ventricle. Thus, global infusion may more effectively prevent deleterious post-infarction remodeling than regional administration alone.