Acute surface-induced thrombosis in the canine ex vivo model: importance of protein composition of the initial monolayer and platelet activation.

The initial events occurring at the blood-polymer interface were examined using a canine ex vivo arteriovenous shunt model. Thrombogenic (fibrinogen) and nonthrombogenic (albumin) proteins were preadsorbed on poly(vinyl chloride), polyethylene, and silicone rubber shunt surfaces, and the blood responses were analyzed using the platelet deposition profile as an indicator of surface thrombogenicity. The distributions of preadsorbed protein molecules on the various polymer surfaces were studied using an immunogold bead (colloidal gold particles coated with antibodies) staining technique and shown to be homogeneous. A sequential protein adsorption technique was developed to probe the nature of competitive protein adsorption and to observe the effect of surface protein concentration on thrombogenicity. The thrombogenicity of a surface was determined by the composition of the initial protein layer rather than the total concentration of protein on the polymer surfaces. The composition of this layer determines the extent of platelet activation and the adhesive strength between platelets and the polymer surface.