The role of von Willebrand factor in hemostasis pathology

Abstract

Von Willebrand factor (VWF) is a multimeric plasma glycoprotein present in endothelial cells, megakaryocytes, platelets, and connective tissue. It mediates platelet adhesion in small arteries. VWF also binds and protects coagulation factor VIII from degradation. Moreover, VWF is involved in inflammatory response, linking hemostasis and inflammation. VWF multimers and platelets attached to damaged or activated endothelium mediate leukocyte recruitment, facilitating local inflammatory response. At shear rates above 5000 s–1, VWF molecules are capable of hydrodynamic activation that changes their conformation from globular to fibrillar. Therefore, VWF plays a key role in cellular hemostasis at high shear rates. Acquired and inherited disfunction, defective synthesis or increased proteolysis of VWF multimers lead to bleeding, as in von Willebrand disease or Heyde syndrome. Pathological activation of VWF may lead to the development of thrombotic complications of coronary artery disease. COVID-19, especially severe form, is characterized by prothrombotic shift in pulmonary vascular bed. Following endothelial damage, VWF plasma level rises and ADAMTS-13 activity decreases. In patients with COVID-19, a change in the VWF/ADAMTS-13 ratio is associated with an increase in the risk of thromboembolic complications. Therefore, assessment of hydrodynamic activation of VWF under flow conditions may be valuable in fundamental research and laboratory diagnostics.