Abstract 11427: Secondary Sphere Formation Enhances the Functionality of Cardiac Progenitor Cells From Murine and Human Cardiac Explants
Recent studies suggest that resident cardiac stem/progenitor cells could be an optimal cell source for repairing a damaged heart. However, cardiac progenitor cells are difficult to maintain their purity and multipotency when propagated in attached 2-dimensional culture in vitro. Here, we investigated a new strategy that enhances cellular potency and provides an enriched source of cardiac progenitor cells. We applied the repeated sphere formation strategy [cardiac explant (3 pieces of tissues: total 15mg) -> migrating cells from explant -> primary cardiosphere (CS)(100 spheres / 35mm PDL dish) -> cardiosphere-derived cells (CDCs)(5x106 cells / 100mm dish) in adherent culture -> secondary CS formation by 3-dimensional culture (5000 spheres from 5x106 cells)]. Secondary CS generated from C57BL/6 mice showed higher potency and differentiation potentials. When transplanted into the infarcted myocardium, secondary CSs engrafted robustly, improved LV dysfunction (14% increase, P<0.05), and reduced infarct sizes (40% decrease, P<0.01) more than CDCs did. In addition to the cardiovascular differentiation of transplanted secondary CSs, paracrine effects, such as, VEGF synthesis and secretion, were found to enhance neovascularization. Next, we investigated the underlying molecular mechanisms for sphere formation by pathway analysis using microarray and blocking experiments of each pathway. ERK/E-selectin and ERK/Sp1/VEGF auto-paracrine loop were responsible for sphere initiation and maturation. When we applied this strategy to adult human cardiac tissues obtained from endomyocardial biopsy, secondary CS was readily generated, and cellular characteristics and molecular pathways of sphere formation were similar to findings in murine. These results provide a simple and reproducible strategy for enhancing cellular potency for cardiac repair. Furthermore, this strategy may be applicable to other types of stem/progenitor cells for cell-based therapy.
- © 2011 by American Heart Association, Inc.