Abstract 344: Naturally Derived Cardiac Extracellular Matrix for Cardiac Progenitor Cell Therapy

Abstract

Cardiovascular disease is the leading cause of death in the United States. Following acute myocardial infarction, there is dramatic myocyte loss, and the cells are replaced with a collagen scar. Cell therapy directed toward regenerating infarcted myocardium suffers from poor retention of cells, possibly because the conditions are not ideal to support injected cells. Many studies show the local microenvironment is a potent regulator of cell fate. Therefore, we hypothesize that culturing cardiac progenitor cells (CPCs) on a naturally derived, cardiac extracellular matrix (cECM) will increase their function. CPCs were isolated from rat cardiac tissue-homogenate with magnetic beads conjugated with c-kit antibodies. Porcine, cardiac extracellular matrix (cECM) was decellularized, digested, and lyophillized to be used as a coating material. CPCs were cultured on cECM and examined for cardiogenic lineage markers, survival, proliferation and adherence. Our results show that CPCs cultured on cECM proliferate better (2.9-fold) as compared to COL (2.3-fold; p<0.05). Additionally, CPCs demonstrate improved resistance to serum-starvation-induced apoptosis when cultured on cECM (40% ± 14%) as compared to COL (53% ± 14%; p<0.001). Furthermore, CPCs adhered more strongly to cECM than COL as measured using microfluidics. CPCs showed enhanced progression toward the cardiomyoctye lineage when cultured on cECM (nkx2.5: 2.3 ± 0.4-fold; α-myosin heavy chain: 14.6 ± 4.4-fold; troponinC: 2.4 ± 0.2-fold; p-values <0.05) as compared to COL. This was confirmed at the protein level with Gata-4 (1.8 ± 0.1-fold; p<0.001) and Nkx2.5 (1.6 ± 0.2-fold; p<0.05). A reduction in fibroblast specific protein-1 (0.5 ± 0.1-fold) was also seen on cECM as compared to COL and suggests the CPCs are less likely to contribute to scar formation. While these conditioned cells have not yet been examined in an in vivo setting, our comparison to COL mimics both the naked injection of these cells into an infarct zone, and comparison to a commonly used cell delivery vehicle. Our data suggest that CPCs delivered with cECM are more likely to survive and differentiate in the infarct zone than cells delivered by themselves or in collagen.