AN IN-VITRO BOVINE PERICARDIAL HEMOCOMPATIBILITY TESTING SYSTEM

Background and aims of the study: Bovine pericardium has been used as a biomaterial for heart valves since the late 1960s. Cross-linking age nts have been applied routinely to reduce host-tissue response, includ ing antigenicity, and to improve tissue leaflet durability. Evaluation of improvements in bovine pericardial valve leaflet calcification and flexibility require that in vitro systems be developed to correlate d ata with results from in vivo studies. This study describes an in vitr o test system used to evaluate the effects of two surface-modifying tr eatments on pericardial tissue hemocompatibility. Methods: Non-fixed a nd glutaraldehyde fixation-processed (GA) bovine pericardial tissues w ere exposed to anticoagulated whole blood for 60 min. Blood was then r emoved, and platelet-poor plasma prepared and frozen at -70 degrees C until analyzed for kallikrein activation and release of platelet facto r 4 (PF4). Blood-exposed tissue samples were analyzed for fibrin(ogen) binding with an anti-fibrinogen antibody and for tissue cellular resp onsiveness (blood cell adherence and aggregation) by scanning electron microscopy. Results: Conditions were determined for minimum extent of pumping action by the minicam system required to allow for solution m ovement while not tearing or wearing the tissue. A blood-tissue exposu re time of 60 min provided sufficient first-pass exposure to evaluate the acute blood-tissue response. The relative degree of both kallikrei n activation and PF4 release was greater in the non-fixed tissue but a greater number of fibrin(ogen) molecules per cm(2) was found on GA-tr eated tissue. Scanning electron microscopy showed a differential cell response of non-fixed tissue compared with GA-treated tissue. Conclusi on: This non-static test system demonstrated great promise for use in routine in vitro hemocompatibility testing of blood-contacting biologi cal biomaterials.