Which glycosaminoglycans are suitable for antithrombogenic or athrombogenic coatings of biomaterials? Part I: Basic concepts of immobilized GAGs on partially cationized cellulose membrane.

Six different GAGs of different natural origin such as unfractionated heparin (HE), chondroitin sulfate (CS), dermatan sulfate (DS), keratan sulfate (KS), endothelial cell surface heparan sulfate (ESHS), and hyaluronan (HA) have been ionically immobilized onto partially cationized cellulose membranes with a substitution degree of 0.06. The GAGs have been characterized in terms of total sulfate content and relative molecular weight. The amount of immobilized GAGs was 10(3) times higher than the theoretical amount for monomolecular side-to-side coordination on polymer surfaces. In a standardized perfusion system with shear rates of 1050 sec-1, 37 degrees C, and 5 minutes with citrated blood, the level of platelet adhesion was 100% for partially cationized membrane, 90% for HA, 75% for each HE, CS, DS, KS, 5% for unmodified cellulose membrane, and 5% for confluent bovine aorta endothelial cells, referred to subendothelial matrix as standard for 100% platelet adhesion. ESHS-coated membranes were completely inert to platelets. The amount of ionically released GAGs during perfusion was also estimated. The partial cationic membrane is a suitable polymer surface in combination with the perfusion system to estimate the hemocompatibility of ionically immobilized water-soluble polyanions in terms of platelet adhesion at defined shear rates. The results of platelet adhesion are discussed in terms of structure and analytical parameter of the immobilized GAGs.