Comparing the in vivo and in vitro effects of hypoxia (3% O 2 ) on directly derived cells from murine cardiac explants versus murine cardiosphere derived cells.

Coronary heart disease (CHD) is still one of the main causes of death in the world, despite significant advances in clinical treatments. Stem cell transplantation methods have the potential to improve cardiac function and patients' outcome following heart attack, but optimal cell types, cell preparation methods and cell delivery routes are yet to be developed. Mammalian hearts contain a small fraction of progenitor cells which, in culture, migrate out of the cardiac explants, known as explant-derived cell (EDCs) and contribute to spheroids known as cardiospheres (Csphs). Following further culture and cell passaging, Csphs give rise to cardiosphere-derived cells (CDCs). EDCs, Csphs and CDCs show in vitro and in vivo angiogenesis and tissue regeneration in myocardial ischemia. However, CDC and Csph formation is time consuming, expensive and not always successful. Therefore, this study aims to compare EDCs with CDCs and assess the effect of hypoxic preconditioning on their pro-angiogenic potential. The data showed that preconditioning EDCs in hypoxic cell culture enhances cell growth, viability and expression of stem cell and pro-angiogenic markers more than CDCs. In vivo experiments using a sub-dermal matrigel plug assay showed that EDCs and CDCs alone have limited pro-angiogenic potential; however, hypoxic preconditioning of EDCs and CDCs significantly enhances this process. Further research will increase our understanding of cardiac stem cell mediated angiogenesis and improve clinical therapies for myocardial infarction (MI) patients.