Cardiac Stem Cells: Biology and Therapeutic Applications

The heart, previously considered a prototypic terminally differentiated organ, is now known to contain reservoirs or compartments of precursor cells. Both postnatal persistence of precursor cells that govern heart formation and adult stem cell niches are described, although the former mechanism appears to be of limited significance. The exact nature and role of adult cell niches continues to be debated, as does the degree to which cardiomayocytes turn over in the adult. There continues to be growing support for a new paradigm of cardiac biology in which myocyte homeostasis occurs throughout life. In this paradigm, diseases of the heart can now be viewed as disruptions in the balance between physiologic myocyte loss and replacement. Moreover, a new therapeutic possibility has emerged whereby cardiac regenerative mechanisms may be deployed in the form of cell therapeutics that either replace lost cells primarily or promote emdogenous cellular repair. In this chapter, we review the biology of cardiac stem cells and the growing body of knowledge regarding cell-based therapeutics.