We have demonstrated that human cardiac stem cells (hCSC) derived from end-stage heart failure (ESHF) hearts are markedly superior in improving post-infarct LV function in comparison to age-match control hCSC. The goal of this application is to characterize the molecular mechanisms underlying this improved performance of ESHF-derived hCSC and to optimize their harvest, molecular characterization and application in a clinically-relevant model of post-MI cardiac failure. Improvement of LV function in ESHF patients, particularly children with end- stage heart failure, via stem cell therapy is of enormous importance since heart transplantation is the only other viable option and in limited supply. Despite their encouraging clinical Phase I results, cardiosphere derived cells (CDCs), comprised of heterogeneous cell types, including c- kit+ cells, are still not well characterized1. Our preliminary data shows that ESHF-derived hCDCs isolated from the left atrium improve ischemic left ventricular function better than ESHF-derived hCDCs from the right atrium, but whether different functional activity is present in all other heart chamber-derived hCDCs is still unknown. Furthermore, since we document significantly higher numbers of c-kit+ cells within ESHF-derived CDCs, the frequency of the c-kit+ cells within CDCs may be critical to recovery of function. Finally, ESHF-derived CDCs secrete higher levels of angiogenic cytokines that correlates with increased angiogenesis in the infarcted myocardium and higher levels of HIF-1a, but the mechanism for the increased cytokine secretion is unclear. Our hypothesis is that the effect of ESHF-derived hCDCs in improving myocardial function is dependent on the anatomic site of hCDC origin and molecular mechanisms by c-kit+ and HIF- 1a. These studies will clarify the biology and function of hCDCs by determining: 1) chamber specific differences amongst hCDCs with the potential need to modify for a more powerful myocardial functional activity, 2) the effect of the frequency of c-kit+ cells on LV recovery, and lastly, 3) the role of HIF-1a as a master cytokine regulator of the myocardial function of ESHF- derived hCDCs. ESHF patients, particularly children, are potentially the most to benefit from hCDC based therapies. This application is the first study designed to determine critical characteristics of ESHF-derived hCDCs and to uncover new mechanisms of their functional activity in a manner that may eventually influence future therapeutic interventions.
Heart failure is a common and lethal disease worldwide, affecting nearly 6 million people in the United States. The notion of replacing lost cardiomyocytes through cell-based therapies to attenuate or even reverse deleterious structural consequences of heart failure via remodeling is appealing and holds enormous therapeutic promise. To improve clinical stem cells protocols in the future, we need to better understand the biology of resident cardiac stem cell biology and see how location within the heart, composition of stem cells and physiological states may affect their functional activity.