Collagen-induced thrombosis in murine arteries and veins

Collagen is a powerful thrombotic stimulus that functions by direct and indirect binding to various platelet receptors. A variety of collagen types are known and several (e.g., collagen Types I, III, IV) are found in vascular tissues and are exposed upon disruption of the endothelium or more extensive vessel wall rupture. Some murine models of thrombosis purport to expose collagen to initiate thrombosis, however, the nature and extent of this exposure is not clear. This study was undertaken to place a known collagen-dominated surface into the in vivo arterial or venous circulation as a method for direct study of collagen-induced thrombosis in mice. The epigastric artery was removed from donor mice and a microsuture with attached needle was knotted into one cut end. Anesthetized mice had this needle/suture/small-artery inserted into and out of a 0.5-mm length of the larger carotid artery or femoral vein, leaving the collagen-rich adventitial surface of the epigastric artery intralumenally in the larger vessel. Extensive platelet and fibrin deposition on this surface were in evidence and were quantitated with fluorescence imaging; administration of clopidogrel reduced thrombus development in both arteries and veins. A method was developed to evert the epigastric artery and disrupt the exteriorized endothelium; with the same needle/suture vessel-insertion technique, this surface stimulated significantly less thrombotic response in both arteries and veins, suggesting differential thrombogenesis based on the molecular composition of the induction factor. This new model of thrombosis offers a method for directly assessing the role of collagen-mediated thrombosis in murine arteries and veins.