Endothelium-derived agents in pericyte function/dysfunction

The major components of blood vessels are the vascular endothelium and its supporting smooth muscle. Significant strides have been made in the underst anding of the cellular and molecular biology of these tao cell types and in particular their interactions have been the subject of much interest and d ebate over the past two decades. The vascular endothelium is now known to p rofoundly influence the synthetic and motor functions of the underlying smo oth muscle and participate in the pathogenesis of all the major vascular di sorders. Similarly, the vascular smooth muscle has important effects on the overlying endothelium, and any disruption in the cellular physiology of ei ther cell type can result in dysfunction with important effects on blood fl ow and vascular permeability The majority of this accumulated knowledge rel ates to the vascular cells of the macrocirculation. Pericytes are the supporting cells of the microvasculature and a body of ev idence is now available to show that similar regulatory mechanisms and vess el-wall cross-talk exists between these cells and the microvascular endothe lium. Nowhere are these interactions more important than in the retinal mic rocirculation where autoregulation is vital for the maintenance of smooth a nd uninterrrupted blood flow. This review focuses on the interactions betwe en retinal microvascular endothelial cells and their associated pericytes a nd examines the role of the endothelial cell and the pericyte in the pathog enesis of disease, (C) 1999 Elsevier Science Ltd. All rights reserved.