Molecular Imaging of Platelet-Endothelial Interactions and Endothelial von Willebrand Factor in Early and Mid-Stage Atherosclerosis

Background— Nonthrombotic platelet–endothelial interactions may contribute to atherosclerotic plaque development, although in vivo studies examining mechanism without platelet preactivation are lacking. Using in vivo molecular imaging at various stages of atherosclerosis, we quantified platelet–endothelial interactions and evaluated the contribution of major adhesion pathways. Methods and Results— Mice deficient for the low-density lipoprotein receptor and Apobec-1 were studied as an age-dependent model of atherosclerosis at 10, 20, 30, and 40 weeks of age, which provided progressive increase in stage from early fatty streak (10 weeks) to large complex plaques without rupture (40 weeks). Platelet-targeted contrast ultrasound molecular imaging of the thoracic aorta performed with microbubbles targeted to GPIbα demonstrated selective signal enhancement as early as 10 weeks of age. This signal increased progressively with age (almost 8-fold increase from 10 to 40 weeks, analysis of variance P Conclusions— Platelet–endothelial interactions occur in early atherosclerosis. These interactions are in part caused by endothelial von Willebrand factor large multimers, which can be reversed with exogenous ADAMTS13.