Collagen Coated Gelatine Tubes for the Investigation of Platelet Adhesion and Subsequent Platelet Aggregation Under Controlled flow Conditions

Aggregometer studies do not discriminate between platelet adhesion and platelet aggregation. Therefore, we prepared a homogenous collagen surface which could be exposed to whole blood in a perfusion chamber under controlled flow conditions. Artificial “vessel” segments were prepared by dipping glass rods into 20% gelatine and, after air-drying, cross-linking the gelatine in 2.5% glutaraldehyde. Segments of 1 cm length were then drawn on the rod of the perfusion chamber and coated with 300 μl of neutral salt soluble collagen (2.2 mg/ml). Surface coverage with collagen was virtually complete (96%–100%). Uncoated or collagen-coated gelatine segments were exposed to citrated rabbit blood for periods up to 40 min. Platelet-surface interaction was evaluated morphometrically. On uncoated segments surface coverage with platelets amounted to 31% and 50% after 10 min and 40 min (the corresponding ratios of contact/spread platelets were 2.6 and 1.5). Only 0.1% thrombi were found. On collagen-coated segments surface coverage with platelets amounted to 57% and 83% after 10 min and 40 min (the corresponding ratios of contact/ spread platelets were 0.1 and 0.0); platelet thrombi were found on 33% and 42% of the surface after 10 min and 40 min. Platelet adhesion and subsequent aggregation on the collagen-coated artificial surface is similar to that observed on α-chymotrypsin digested subendothelium. The results suggest that fibrillar collagen triggers rapid spreading on a surface, a reaction which is closely associated with the formation of platelet thrombi. The latter phenomenon is thought to be caused by the release of aggregating agents from the spreading platelets.