Figure 1.

VWF Function. VWF is stored in Weibel-Palade bodies (WPB) and deposited in extracellular matrix of vascular endothelial cells, as well as circulating in plasma as globular form. (A) At the site of injury in presence of shear stress globular VWF attach to the exposed subendothelial collagen layer and (1) unravel to form the most adhesive form of VWF. The extracellular matrix deposited VWF is similarly exposed to bind platelets. Platelets captured by unraveled VWF are (2) activated and form VWF-platelet aggregates to seal the damaged vessel wall and prevent blood leakage while repair. Following the completion of repair process ADAMTS13 (Scissors) will (3) cleave UL VWF to smaller VWF multimers to resolve platelet aggregates. (B) External stimuli induce secretion of VWF, which may bind to endothelial luminal surface membrane and mediate platelet aggregate formation through a similar process as that observed at the site of vascular injury.