Thrombogenicity adsorbed fibrinogen

The lower thrombogenicity of the RF plasma/TFE surface may result from insufficient adsorbed fibrinogen to trigger platelet activation. 

The data on protein adsorption as affected by immobilized heparin is quite contradictory. In Refs.114> and115), serum albumin was shown to be predominantly adsorbed by the HCP, whereas in the majority of other works the observed dependence was the opposite. Table 14 compiles the results of the studies of the absorption of plasma proteins by HCP of two different types 64). Such thrombogenic proteins as fibrinogen and thrombin are seen to be the ones adsorbed most. 

The amount of fibrinogen adsorbed on the glass-contacting surface of the SPU/block-type PMEH membrane was reduced significantly compared with that of SPU. Also, blood cells did not adhere. The orientation of the polyfMPC) segments in the block-type PMEH allowed for sufficient antiadhesion function. Based on these considerations, it appears that the molecular architecture of the blended polymer provides for biomaterials with suitable mechanical properties and reduced thrombogenicity. 

Other difficulties in in vitro studies arise from the finding that adsorption is changed by flow conditions and by the presence of blood formed elements. In addition, with blood, a stable protein adsorbate appears to be formed only after exposure of a day or more. Despite these difficulties, some adsorption characteristics appear to correlate with thrombogenicity. Preferential adsorption of albumin and low fibrinogen adsorption appear to denote thromboresist-ant surfaces and this is used by many as an indicator of thrombo-resistance. 

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