THE COVALENT GRAFTING OF FIBRONECTIN AT THE SURFACE OF POLY(ETHYLENE-TEREPHTHALATE) TRACK-ETCHED MEMBRANES IMPROVES ADHESION OF RAT HEPATOCYTES

[H-3]methylated fibronectin (FN) has been immobilized on the surface o f poly(ethylene terephthalate) track-etched membranes (PET), carboxyla ted and then activated or not with water-soluble carbodiimide (WSC). U pon washing in 10% SDS or in the nutritive medium used for hepatocytes cultivation (supplemented with 15% newborn calf serum), respectively, 76% and 43% of [H-3]FN are released from the unactivated PET membrane s and those WSC activated. This difference is almost totally abolished when the -NH2 functions of FN have been fully acetylated, to impair t heir reaction with activated -COOH groups. These results strongly sugg est that part of FN is covalently grafted to the activated -COOH of PE T but that, in addition, FN is also adsorbed on this surface. Rat hepa tocytes were inoculated on PET membranes on which FN had been adsorbed and/or grafted. Image analysis clearly indicates that, during the fir st hours of culture, the FN immobilization on WSC activated, carboxyla ted PET membranes, significantly favours the adhesion of hepatocytes. After 24 h, the difference between these substrates decreases, probabl y due to the reconditioning of the PET surface by extracellular matrix constituents secreted by the hepatocytes. Our results confirm that th e nature of the protein-polymer interaction strongly affects cell beha viour.