Saratin, an inhibitor of von Willebrand factor–dependent platelet adhesion, decreases platelet aggregation and intimal hyperplasia in a rat carotid endarterectomy model

Purpose: Post–carotid endarterectomy, thrombosis, and intimal hyperplasia may be decreased by the inhibition of platelet adhesion and activation. In this study, a novel agent, saratin, was used to inhibit platelet-to-collagen adhesion in a rat carotid endarterectomy model. Saratin is a recombinant protein isolated from the saliva of the medicinal leech Hirudo medicinalis , which is thought to act by binding to collagen, and inhibits von Willebrand factor–collagen interaction under conditions of increased shear and therefore, the adherence and activation of platelets at the vessel wall. Saratin has the advantage of being a nonsystemic, site-specific topical application. Methods: A rat carotid endarterectomy model was used in which an open technique with arteriotomy and intimectomy was used. Saratin was applied to the endarterectomized surface of the carotid artery before arterial closure. End point measurements included platelet adhesion, thrombosis rate, intimal hyperplasia development, bleeding times, and platelet counts. Electron micrographs of carotid arteries were used for quantitative analysis of platelet aggregation and platelet counts. Intimal hyperplasia and thrombosis were assessed with computer-assisted morphometric analysis of elastin-stained carotid artery sections with direct measurement of the intimal hyperplasia area. Results: The topical application of saratin significantly decreased platelet adhesion compared with controls at 3 hours after carotid endarterectomy (64 ± 17 vs 155 ± 33 platelets per grid, P =.05), and 24 hours after carotid endarterectomy (35 ± 11 vs 149 ± 37 platelets per grid, P =.0110), respectively. A percent luminal stenosis, as a measure of intimal hyperplasia, was significantly decreased with saratin application compared with controls (10.9% ± 1.8% vs 29.8% ± 6.8%, P =.0042). This decrease in intimal hyperplasia formation correlated with the inhibition of platelet adhesion. Thirty-three percent of control arteries were found to be thrombosed 2 weeks after carotid endarterectomy compared with a 0% thrombosis rate in the saratin-treated group (P =.0156). No increased bleeding was encountered along the arterial suture line in the saratin group. Bleeding times and systemic platelet counts were not found to change significantly in the saratin-treated rats compared with control rats at 3 and 24 hours after endarterectomy. Conclusion: Saratin significantly decreased platelet adhesion, intimal hyperplasia, luminal stenosis, an