Sites of injury: The endothelium

Abstract

An estimated 6 × 1013 endothelial cells form the inner surface of blood vessels in man. As such, in an adult human being they cover a total area of approximately 3,000 m2 and have a total volume comparable to that of the liver (Huttner and Gabbiani 1982; Münzel et al. 2008). Traditionally, the endothelium has been assumed to be a passive barrier between the blood and the surrounding tissue; however, over the past 2-3 decades numerous additional roles for the endothelium have been described. These findings challenge the concept of the endothelium as a passive interface and leads to the notion of the endothelium being a highly active organ involved in the regulation and modulation of a vast number of physiological and pathophysiological processes. Endothelial cells are essential in the regulation of vascular tone, control of transendothelial movement of fluid, solutes and macromolecules, modulation of inflammation and leukocyte adhesion, promotion and inhibition of growth of new blood vessels and regulation of blood fluidity and platelet aggregation, fibrinolysis and coagulation. © 2011 Springer-Verlag/Wien.