Factor VIII is an essential element for a correct clotting process. However, its function is closely related to another clotting factor, von Willebrand factor (vWF).
This factor is normally produced by endothelial cells, i.e. the cells that line the inner wall of the blood vessels, and by megakaryocytes, or platelet precursors. Once it has been produced, von Willebrand factor can be either be stored inside the endothelial cells or immediately released into the plasma, where it recognises and binds with factor VIII to create the factor VIII-von Willebrand factor complex.
Once it has bound to factor VIII, von Willebrand factor plays a protective and supportive role with a number of functions. The most important are:
- the stabilisation of factor VIII and protection against the action of activated protein C, a protein that tends to attack and break down the factor VIII circulating in the plasma;
- transportation of factor VIII to points in which a lesion has occurred and the clotting process must be activated;
- protection of factor VIII from attack by
This last function would appear to be particularly important, as the development of inhibitors is still one of the main challenges to be faced in the treatment of haemophilia.
Von Willebrand factor has recently attracted special interest in the field of scientific research and would appear to be a promising element that could play a significant role in both the prevention and the treatment of inhibitors.
- Peyvandi F. et al, (2011). Role of von Willebrand factor in the haemostasis. Blood Transfusion, 9(2), s3–s8.
- Peyvandi F. et al, (2016). A Randomized Trial of Factor VIII and Neutralizing Antibodies in Hemophilia A. The New England Journal of Medicine, 374(21), 2054-64.