Protein and platelet interactions with thermally denatured fibrinogen and cross-linked fibrin coated surfaces

In this work the hypothesis that a mature, cross-linked fibrin clot, pre-fo rmed on a biomaterial, may be relatively nonthrombogenic was investigated. A cross-linked fibrin layer was formed on polyethylene which had been preco ated with thermally denatured fibrinogen. Plasma protein adsorption and pla telet interactions with the cross-linked fibrin and denatured fibrinogen su rfaces were investigated. The adsorption of albumin, fibrinogen, and fibron ectin from plasma was measured. For all three proteins, the cross-linked fi brin surface exhibited much higher levels of adsorption than either the the rmally denatured fibrinogen or the polyethylene surface. Vroman peaks were observed for fibrinogen and fibronectin on polyethylene but not on the cros s-linked fibrin and thermally denatured fibrinogen materials. In dilute pla sma the thermally denatured fibrinogen surface showed considerable resistan ce to protein adsorption. However, at plasma concentrations greater than ab out 5% normal, this protein resistance was apparently lost. Platelet intera ctions (adhesion and release of granule constituents from adherent platelet s) using suspensions of washed platelets in the presence of red cells were investigated at shear rates of 50, 300, and 525 s(-1) using a cone and plat e apparatus. The levels of platelet adhesion on the different surfaces were in the order: adsorbed fibrinogen > cross-linked fibrin > thermally denatu red fibrinogen = polyethylene. Platelets on the cross-linked fibrin surface also showed high levels of release indicating significant platelet activat ion. Scanning electron microscopic observations were in agreement with the platelet adhesion and release data, showing only a few (but well-spread) ad herent platelets on the cross-linked fibrin surface. (C) 1998 Elsevier Scie nce Ltd. All rights reserved.