Covalent grafting of fibronectin and asialofetuin at surface of poly(ethylene terephthalate) track-etched membranes improves adhesion but not differentiation of rat hepatocytes.

The adhesion and differentiation of rat hepatocytes onto track-etched poly(ethylene terephthalate) (PET) membranes were studied. Native or [3H]methylated fibronectin (FN) or asialofetuin (ASF) were immobilized onto oxidized PET membranes, preactivated or not with carbodiimide (WSC). Radiochemical assay and ELISA indicated that upon washing in SDS or in serum-containing medium, significantly less FN was released from WSC-activated membranes that from unactivated ones. These differences were abolished when the NH2 functions of FN were fully acetylated, suggesting that part of FN was covalently grafted on WSC-activated PET. Although weaker, a comparable effect was observed with ASF. Hepatocytes adhered faster on membranes on which FN was grafted than adsorbed, reaching values comparable to collagen-coated PET; after 24 h these differences decreased. Experiments with cycloheximide or at 4 degrees C suggested that this results from secretion of extracellular matrix adsorbing on PET. Phase I or II biotransformation activities of cells cultured for 1-4 days on FN-, ASF-, or collagen-treated substrates were not significantly different. These results indicate that stable immobilization of FN (covalent grafting) onto PET membranes significantly accelerates adhesion of hepatocytes but does not affect their differentiation. This may result from a progressive surface reconditioning by neosynthesized extracellular matrix.