Identification of a coronary stem cell in the human heart.

Human ischemic cardiomyopathy is characterized by de novo cardiomyogenesis, which is limited to the surviving portion of the ventricle, and by organ hypertrophy that develops as a chronic response to ischemic injury. Although myocyte hypertrophy and myocyte regeneration restore the original myocardial mass, the coronary vasculature remains defective and the extent and regulation of myocardial perfusion are severely impaired. Recently, vascular stem cells (VSCs) have been identified in the coronary circulation. VSCs express c-kit and the vascular endothelial growth factor receptor-2, KDR. These cells are self-renewing, clonogenic, and multipotent in vitro and in vivo. In animal models of critical coronary artery stenosis, VSCs form large conductive coronary arteries and their distal branches. This degree of vasculogenesis replaces partly the function of the occluded coronary artery improving myocardial perfusion and positively interfering with the development of the post-infarction myopathy. Cell therapy directed to the restoration of the integrity of the coronary circulation, the replacement of atherosclerotic coronary vessels, or both, would change dramatically the goal of cell therapy for the ischemic heart: the prevention of myocardial injury would become the end-point of cell therapy rather than the partial recovery of established damage.