Vascular endothelium, haemostasis and thrombosis.

The vascular endothelium consists of a monolayer of cells. Integrity of the endothelium is essential for maintenance of blood fluidity as the subendothelium is composed of structures which rapidly activate platelets and coagulation. Recent research indicates that the endothelium is involved in other processes particularly vasoactivity, immune reactions and inflammatory processes. Much of the information has come from experiments using cells in culture and there has been considerable progress in defining synthesis and release of endothelial products involved. Of particular interest is the evidence for endothelial coagulant activity and exposure of binding sites for coagulation proteins, with the simultaneous suppression of antithrombotic activities, all of which can be brought about by inflammatory mediators. Despite the rapid progress in cell biology, clinical applications have tended to lag behind and there are still few aspects of endothelial cell metabolism and pathophysiology which can be precisely defined in patients with disorders in which the endothelium is without doubt actively involved.