Application of a new dynamic flow model for investigating the biocompatibility of modified surfaces

An in vitro model was developed to compare the biocompatibility of four dif ferent coating methods (three heparin and one nonheparin) under hemodynamic conditions. Fresh human donor blood (heparin 5 IU/ml) was recirculated in a standardized experimental circuit. All circuit components were either coa ted or remained uncoated for control purposes. The aim of the study was to investigate a wide spectrum of effects an blood; coagulation parameters (e. g., fibrinogen, ATIII, thrombin-antithrombin-complex), complement parameter s (C1rsC1lnh, C3b(Bb)P, SC5b-9, C5a), differential blood analyses, platelet activation (flow cytometric investigations), PF 4, and PMN-elastase releas e were examined by showing possible trends. All heparin coated systems redu ced platelet stimulation in comparison to untreated biomaterials. Leukocyte activation was reduced to different degrees depending upon the coating met hod used. Complement activation was markedly reduced by all coated systems. The results obtained indicate that the pump driven, dynamic blood flow mod el is suitable to characterize the biocompatibility of surface modified bio materials. Advantages lie in the integration of the different polymers as p arts of the circuit, the low priming volume, and the generation of blood fl ow conditions similar to those that occur in clinical applications.