Mechanisms underlying FeCl3-induced arterial thrombosis

Background: The FeCl3-induced vascular injury model is widely used to study thrombogenesis in vivo, but the processes leading to vascular injury and thrombosis are poorly defined. Objectives: The aim of our study was to better characterize the mechanisms of FeCl3-induced vascular injury and thrombus formation, in order to evaluate the pathophysiological relevance of this model. Methods: FeCl3 was applied at different concentrations (from 7.5% to 20%) and for different time periods (up to 5 min) to mouse carotid or mesenteric arteries. Results: Under all the conditions tested, ultrastructural analysis revealed that FeCl3 diffused through the vessel wall, resulting in endothelial cell denudation without exposure of the inner layers. Hence, only the basement membrane components were exposed to circulating blood cells and might have contributed to thrombus formation. Shortly after FeCl3 application, numerous ferric ion-filled spherical bodies appeared on the endothelial cells. Interestingly, platelets could adhere to these spheres and form aggregates. Immunogold labeling revealed important amounts of tissue factor at their surface, suggesting that these spheres may play a role in thrombin generation. In vitro experiments indicated that FeCl3 altered the ability of adhesive proteins, including collagen, fibrinogen and von Willebrand factor, to support platelet adhesion. Finally, real-time intravital microscopy showed no protection against thrombosis in GPVI-immunodepleted and beta(-/-)(1) mice, suggesting thatGPVI and beta(1) integrins, known to be involved in initial platelet adhesion and activation, do not play a critical role in FeCl3-induced thrombus formation. Conclusion: This model should be used cautiously, in particular to study the earliest stage of thrombus formation.