New insights into the function and regulation of endothelial cell apoptosis.

The sculpting of blood vessels to meet the changing requirements of the tissues they supply is essential for life. Many researchers believe that endothelial cell apoptosis plays an important role in this process. This belief is bolstered by the detection of endothelial apoptosis within remodeling vessels in vivo, the dramatic vascular phenotypes of mice in which regulators of endothelial apoptosis have been inactivated and the apparent dependence of angiogenesis on endothelial apoptosis in vitro. However, when examined carefully, the evidence for or against endothelial cell apoptosis playing an important role in vascular biology is largely indirect and is far from clear-cut. In this review, we will discuss the idiosyncratic process of endothelial cell apoptosis. We will then examine its complex regulation and weigh the in vitro and in vivo evidence that it plays a significant role in mammalian vascular biology.