Endothelium - Function

Function

Endothelial cells are involved in many aspects of vascular biology, including:

• Atherosclerosis
• Barrier function - the endothelium acts as a semi-selective barrier between the vessel lumen and surrounding tissue, controlling the passage of materials and the transit of white blood cells into and out of the bloodstream. Excessive or prolonged increases in permeability of the endothelial monolayer, as in cases of chronic inflammation, may lead to tissue edema/swelling.
• Blood clotting (thrombosis & fibrinolysis). The endothelium normally provides a non-thrombogenic surface because it contains, for example, heparan sulfate which acts as a cofactor for activating antithrombin, a protease that inactivates several factors in the coagulation cascade.
• Inflammation
• Formation of new blood vessels (angiogenesis)
• Vasoconstriction and vasodilation, and hence the control of blood pressure

In some organs, there are highly differentiated endothelial cells to perform specialized 'filtering' functions. Examples of such unique endothelial structures include the renal glomerulus and the blood–brain barrier.