von Willebrand Factor

Examples of von Willebrand Factor in the following topics:

• Hemostasis Disorders

  • The most common blood disorders, Von Willebrand disease, hemophilia, and Factor V Leiden thrombophilia, all involve defects in the amount or activity of factors involved in coagulation.
  • Those affected by von Willebrand disease will have low levels of von Willebrand factor, a protein that helps the blood to clot, and/or their von Willebrand factor does not work properly.
  • In this type of disease, there is a low level of von Willebrand factor.
  • In this type of disease, there is a defect in von Willebrand factor resulting in improper activity.
  • In this type of disease, individuals usually do not produce von Willebrand factor and have very low levels of factor VIII.

• Overview of Hemostasis

  • When endothelial injury occurs, the endothelial cells stop secretion of coagulation and aggregation inhibitors and instead secrete von Willebrand factor, which causes platelet adherence during the initial formation of a clot.
  • Von Willebrand factor causes them to adhere to each other and the walls of the vessel.
  • At least 12 substances called clotting factors or tissue factors take part in a cascade of chemical reactions that eventually create a mesh of fibrin within the blood.
  • Each of the clotting factors has a very specific function.
  • Prothrombin, thrombin, and fibrinogen are the main factors involved in the outcome of the coagulation cascade.

• Platelet Plug Formation

  • During an injury, subendothelial collagen from the extracellular matrix beneath the endothelial cells is exposed on the epithelium as the normal epithelial cells are damaged and removed, which releases von Willebrand Factor (VWF).
  • The released chemicals include ADP, VWF, thromboxane A2, platelet-derived growth factor (PDGF), vascular endothelial growth factor (VEGF), serotonin, and coagulation factors.
  • The other factors released during platelet activation perform other important functions.
  • The coagulation factors include factor V and VIII, which are involved in the coagulation cascade that converts fibrinogen into fibrin mesh after platelet plug formation.