von Willebrand factor: at the crossroads of bleeding and thrombosis

Hemostasis and thrombosis represent two sides of the same coin. Hemostasis maintains blood fluidity in the vascular system while allowing for rapid thrombus formation to prevent excessive hemorrhage after blood vessel injury. Thrombosis is a pathologic extension of the normal hemostatic mechanism, occurring when unwanted clot formation develops in certain pathological situations. The molecular mechanisms underlying both phenomena are fundamentally identical. One of the key players in both processes is the plasma glycoprotein von Willebrand factor, which perfectly illustrates this duality between hemostatic and thrombotic mechanisms. The purpose of this review is to discuss novel findings on the role of von Willebrand factor at this interface, and how some of these findings may help develop new therapeutic strategies.