Von Willebrand factor, a key protein in the exposure of CD62P on platelets

When a biomaterial is introduced into the body water, electrolytes, and pro teins adsorb to the surface. Platelets are then the first cells to interact with the surface adsorbed protein layer. We have studied the role of von W illebrand factor (vWF) for platelet-protein interaction by measuring differ ent platelet responses to protein- and plasma-coated hydrophobic glass surf aces. A high exposure of CD62P on the platelet surface was seen after 10 mi n of incubation on platelets interacting with vWF and normal plasma-coated surfaces (79 and 67%, respectively). On the surfaces coated with albumin an d factor VIII deficient plasma, the exposure was low (11 and 27%, respectiv ely). A higher formation of filipodial extensions on the platelets was seen on the surfaces coated with vWF and normal plasma than on the surfaces coa ted with albumin or factor VIII deficient plasma. No significant difference s were seen between the surfaces regarding the platelet release of PF4, ATP , or phospholipids. As shown by these results, vWF is a specific regulator of the exposure of CD62P by platelets and hence important for the interacti on between platelets and later arriving neutrophils at biomaterial surfaces . (C) 2001 Elsevier Science Ltd. All rights reserved.