The contributions of the α2β1 integrin to vascular thrombosis in vivo

The alpha(2)beta(1) integrin serves as a receptor for collagens, laminin, and several other nonmatrix ligands. Many studies have suggested that the alpha(2)beta(1) integrin is a critical mediator of platelet adhesion to collagen within the vessel wall after vascular injury and that the interactions of the platelet alpha(2)beta(1) integrin with subendothelial collagen after vascular injury are required for proper hemostasis. We have used the alpha(2)beta(1) integrin-deficient mouse to evaluate the contributions of the alpha(2)beta(1) integrin in 2 in vivo models of thrombosis. Studies using a model of endothelial injury to the carotid artery reveal that the alpha(2)beta(1) integrin plays a critical role in vascular thrombosis at the blood-vessel wall interface under flow conditions. In contrast, the alpha(2)beta(1) integrin is not required for the formation of thrombi and pulmonary emboli following intravascular injection of collagen. Our results are the first to document a critical in vivo role for the alpha(2)beta(1) integrin in thrombus formation at the vessel wall under conditions of shear following vascular injury.