Stem cells for myocardial repair

The adult human heart has limited regenerative capacity and therefore any significant myocardial damage results in progressive deterioration in its function. Cell-based cardiac repair represents an exciting approach for rebuilding the injured heart. Consequentially, during the last decade, significant efforts have been made to assess the potential role of skeletal myoblasts, foetal cardiomyocytes, bone marrow stem cells, endothelial progenitors, resident cardiac progenitor cells, and embryonic stem cells (ESC) to restore the myocardial performance. Clinical translation of these basic studies has progressed rapidly with several Phase I and II clinical trials, utilizing autologous bone marrow cells and skeletal myoblasts, being well underway. In this review, we will describe these basic and clinical efforts. A specific emphasis will be placed on the potential role of human ESC for myocardial repair. These unique pluripotent cell lines can be propagated in the undifferentiated state in culture and coaxed to differentiate into cell derivatives of all three germ layers, including cardiomyocytes. The potential applications of this unique differentiating system in the emerging field of cardiovascular regenerative medicine will be discussed with special emphasis on the steps required to fully harness their unique potential.