Role of Plasma Proteins on Platelet Adhesion

Vroman et al (28) extensively studied the initial phase of blood-surface interactions. They have postulated that on hydrophilic surfaces (eg. Glass), Fg is deposited within seconds along with traces of high molecular weight kininogen (HMWK) and factor XII. Then more HMWK and factor XII arrive and displace Fg. Platelets adhere most, where fibrinogen remains. Thus, Fg plays a key role in platelet-surface attachment and subsequent thrombus formation. 

The platelet receptor-endothelial matrix protein interactions have been well characterized. Under high shear conditions, this attachment is mediated by the binding of von Willebrand Factor (vWF) to the glycoprotein receptor GPlb-lX (27). Secondary attachment between platelets results in thrombus formation, which is caused by Fg or vWF-mediated crosslinking of GPl lb-111a receptors on adjacent 

While the receptors involved in platelet adhesion to the subendothelium have been studied extensively, the receptors involved in platelet adhesion to prosthetic materials are less well identified. The biomaterials adsorb a It er of plasma proteins on their surface tqxm exposure to blood. The content of this protein ItQror varies with time and induces Fg, Ig G, Fn, vWF and vibronectin (18,19) etc.. For which there are specific surface receptors on platelet surface (28). 

Platelet adhesion end spreading to protein coated glass, for IS minutes exposure to wadied platdetst 

The photomicrographs of platelet adhesion on protein coated glass, after e qx)sing with wasted cells and whole blood, under lOOOS shear, for 15 minutes are shown in figures 2 and 3 respectively. 

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