Differential regulation of endothelial cell barrier function

The endothelium serves as a semipermeable barrier separating the circulation from the surrounding interstitium. Its luminal surface is coated with a negatively charged glycocalyx comprised of membrane-bound proteoglycans and glycoproteins. The tight apposition of individual endothelial cells (ECs) with neighboring cells via intercellular junctions acts as a significant determinant of basal endothelial barrier function. Separately, focal adhesions, the integrin-based linkages between the extracellular matrix and the endothelial cytoskeleton, provide strong tethering of the endothelium to the vessel wall, a process that also contributes to barrier integrity.