ABSTRACT
This chapter focuses separately on the stem cells that constitute the vasculature and the heart, although there is some overlap in that the cardiac endothelium is contiguous with that in vessels and both tissues require replenishment of endothelial cells and smooth muscle. It divides discussion of vessel wall progenitors into three categories, namely endothelial progenitor cells, smooth muscle progenitor cells, and multipotent vascular stem cells that encompass so-called pericytes and mesenchymal stem cells. The mammalian heart wall is separated into three layers, namely the innermost endocardium that forms a continuum with the endothelial lining of the blood vessels, the middle myocardium, and the outermost epicardium. A number of cardiac progenitor cell types have been described within the adult mammalian heart, but there is not general agreement on their molecular identity or specific markers with which they can be isolated or indeed whether there are one or more progenitor cell types.
