FIBRILLIN CONTAINING ELASTIC MICROFIBRILS SUPPORT PLATELET-ADHESION UNDER DYNAMIC SHEAR CONDITIONS

The vascular subendothelium contains macromolecular structures called microfibrils. Type VI collagen is one protein found in microfibrils th at supports platelet adhesion and aggregation and we have previously e valuated the roles of platelet receptors and vWf involved in these pro cesses under physiological shear conditions. Here we investigate the a bility of fibrillin containing elastic microfibrils to support mural t hrombus formation. Our results show that elastic microfibril surfaces support platelet adhesion under low shear conditions at a level simila r to collagen VI tetramers. However, the degree of aggregation on the elastic microfibril surface is much higher. Both adhesion and aggregat ion were shown to be mediated by the GPIIb-IIIa platelet receptor. Ela stic microfibrils do not support the formation of mural thrombi under high shear conditions. These results suggest roles for both collagen V I and fibrillin containing elastic microfibrils in modulating the plat elet response to blood vessel injury.