Formation of the coronary vasculature during development.

The formation of the coronary vasculature involves a series of carefully regulated temporal events that include vasculogenesis, angiogenesis, arteriogenesis and remodeling. This review explores these events, which begin with the migration of proepicardial cells to form the epicardium and end with postnatal growth and remodeling. Coronary endothelial, smooth muscle and fibroblast cells differentiate via epithelial-mesenchymal transformation; these cells delaminate from the epicardium. Following the formation of a tubular network by endothelial cells, an aortic ring of endothelial cells penetrates the aorta at the left and right aortic cusps to form the two ostia. Smooth muscle cell recruitment occurs rapidly and the coronary artery network begins forming as blood flow is established. Recent studies have identified a number of regulatory molecules that play key roles in epicardial formation and the transformation of its component cells into mesenchyme. Moreover, we are finally gaining some understanding regarding the interplay of angiogenic growth factors in the complex process of establishing the coronary vascular tree. Understanding coronary embryogenesis is important for interventions regarding adult cardiovascular diseases as well as those necessary to correct congenital defects.