ADHERENT PLATELET MORPHOLOGY ON ADSORBED FIBRINOGEN - EFFECTS OF PROTEIN INCUBATION-TIME AND ALBUMIN ADDITION

The composition of the protein layer adsorbed to a polymer has been th ought to be important for the adhesion of platelets. The state of acti vation of adherent platelets is an additional factor that may be a pre dictor of biocompatibility. Activation refers to the degree of change from discoid shape to any of several spread shapes. The conformation a nd orientation of adsorbed adhesive proteins, which interact with rece ptors on the membrane of platelets, such as fibrinogen, fibronectin, a nd von Willebrand factor, may also be important for platelet adhesion and activation. This work deals with the behavior of fibrinogen adsorb ed to PMMA alone, where the experimental variable was incubation time with the substrate, and with adsorbed fibrinogen mixed with albumin, w here the experimental variable was the molar percent of fibrinogen in the adsorption solution. Shorter protein incubation times and increase d albumin levels in the initial fibrinogen adsorption solution enhance d the percentages of activated platelet morphologies and increased ads orbed fibrinogen redistribution by the platelet. Lower concentrations of albumin in the initial adsorption solution enhanced platelet adhesi on numbers; fibrinogen incubation time had no effect. Together, these factors can contribute to the biocompatibility of a biomaterial throug h their effect on platelet adhesion and activation. (C) 1994 John Wile y & Sons, Inc.