Human embryonic stem cells for myocardial regeneration

Terminally differentiated adult cardiomyocytes have limited regenerative capacity and therefore any significant cell loss may result in the development of progressive heart failure. Cell replacement therapy is a promising new approach for myocardial repair but has been limited by the paucity of cell sources for functional human cardiomyocytes. The recent establishment of the human pluripotent embryonic stem (ES) cell lines may present a novel solution for this cell-sourcing problem. The ES lines were derived from human blastocysts and were shown to be capable of continuous undifferentiated proliferation, in vitro, while retaining the capability to form derivatives of all three germ layers. More recently, a reproducible cardiomyocyte differentiation system was established using these unique cells. The current review describes the derivation and properties of human ES cells and the characteristics of the cardiomyocytes derived using this unique differentiating system. The possible applications in several research and clinical areas are discussed as well as the steps required to fully harness the potential of this new technology in the fields of myocardial cell replacement and tissue engineering.