Von Willebrand factor human

Clotting factor VIII or coagulation factor VIII is a glycoprotein involved in the intrinsic pathway of the blood coagulation cascade. It normally circulates in human plasma in a stable complex with von Willebrand factor (vWF), which is a multimeric glycoprotein. vWF acts as a carrier and stabilizing protein for coagulation factor VIII, as it is prone to rapid proteolysis and clearance from plasma. vWF consists of disulfide bridge linked dimers of the 225-kDa single-chain molecule, with the large multimer of vWF being the most effective in supporting adhesion between platelet and collagen or platelet receptors. vWF in circulation functions as a molecular carrier for various proteins other than coagulation factor VIII, such as osteoprotegerin and galectins and recruits platelets upon vascular injury to promote platelet adhesion to the damaged vascular sub-endothelial matrix and platelet aggregation.

Both coagulation factor VIII and vWF are essential blood clotting factors in normal hemostasis; however, certain blood disorders such as hemophilia A and von Willebrand disease are associated with reduced or deficient levels of functional clotting factors. Reduced levels of vWF in plasma lead to decreased levels and activity of factor VIII, and abnormal platelet function, thereby resulting in excessive bleeding. Exogenous sources of human vWD aim to restore the levels of vWF in circulation to control and prevent bleeding episodes in patients with the reduced capability of blood clotting. Exogenous vWF treatment is also available as a combination product also containing exogenous coagulation factor VIII to replenish the levels of both clotting factors.