Von Willebrand factor and thrombosis: risk factor, actor and pharmacological target

Thrombosis is the pathological face of the hemostatic process, and is still the major cause of death in the Western society. Many different components have been identified that contribute to the thrombotic occlusion of the vasculature and several therapeutic approaches have been developed to treat this severe clinical complication. In the last several years, a number of new agents have been under (pre)clinical investigation that are targeting von Willebrand factor (VWF), a protein that nicely exemplifies the thin line between the normal hemostatic process and an overly active system that gives rise to thrombotic events. Indeed, several epidemiological studies have found that increased plasma levels of VWF are associated with an increased risk for cardiovascular complications. VWF is a multimeric protein that is pertinent to the recruitment of platelets to the growing thrombus. VWF and platelets circulate together without interacting under normal conditions, and should combine into a thrombus selectively when necessary. This delicate process is highly regulated by various endothelial- and plasma proteins as well as by changes in shear stress. In the present review, an update is provided about our current knowledge on VWF as a risk factor, mediator and pharmacological target in association with thrombosis.