PLATELET DEPOSITION ONTO FIBRIN-COATED SURFACES UNDER FLOW CONDITIONS

Fibrin solubilized in NaBr/acetic acid was used to coat glass tubes. Platelet deposition on fibrin-coated surface and release from these adherent platelets were studied in an in vitro flow system. When a mixed suspension of washed platelets and red cells flowed through a fibrin-coated glass tube, only platelets deposited onto the fibrin-coated surface. The density of adhered platelets increased with flow time and decreased with distance from the tube inlet. The adhesion rate increased with increasing shear rates from 45 s⁻¹ to 180 s⁻¹. This adhesion process appears to fit a diffusion-limited mathematical model. Comparing with glass and other protein-coated surfaces such as collagen, fibrinogen, or albumin coated surfaces, the number of adhered platelets per unit area decreased in the following order: collagen > fibrin> fibrinogen > glass > albumin. On the other hand, the degree of release reaction from these platelets decreased by another order: collagen > glass > fibrinogen > fibrin. We observed little release from platelets that were in contact with a fibrin-coated surface. Our results support that platelets specifically adhere to fibrin-coated surface and that this interaction does not induce platelet release.