c-kit+ Cardiac Stem Cells: Spontaneous Creation or a Perplexing Reality.

c-kit+ Cardiac Progenitors of Neural Crest Origin Hatzistergos et al PNAS. 2015;112(42):13051–13056. One of the lingering controversies in the field of cardiac regenerative medicine has been around the origin of c-kit+ cardiac stem cells in the heart and their contribution toward cardiac homeostasis. A recent study reports that a subpopulation of c-kit+ cardiac progenitors emerges from the cardiac neural crest (CNC) with the capacity to give rise to cardiomyocytes. Contribution of CNC-derived c-kit+ cells to cardiac myocyte development is regulated by bone morphogenetic protein (BMP). However, ex vivo manipulation of CNCc-kit cells reveals efficient transformation to early cardiac progenitors. The idea of the heart as a mitotic organ capable of cardiomyocyte renewal has been the subject of scientific polarization for over a decade. The ensuing years have witnessed a relentless quest to identify the true cardiac stem cell capable of regulating cardiac homeostasis, thereby providing evidence for any mitotic nature of cardiac tissue. Importantly, studies have effectively shown that similar to other organs, the heart contains a small population of resident stem cells responsible for cellular turnover to physiological and pathological demands.1 Ex vivo manipulation of this cardiac stem cell population unequivocally has demonstrated the repair potential of these cells after adoptive transfer in pathological heart tissue in a variety of small2 and large animal models.3 That being said, the controversy has been the true identity of a putative cardiac stem cell as recent studies have shown that this cell in question does not have significant cardiomyocyte forming potential and although it may have exogenous repair processes, its endogenous repair potential is not robust.4 The presented notion in 2003 was that the tyrosine kinase protein CD117 or c-kit was a bona fide marker to identify and study resident cardiac stem cells, …