MULTILAYER RAT HEPATOCYTE AGGREGATES FORMED ON EXPANDED POLYTETRAFLUOROETHYLENE SURFACE

Feasibility of using a macroporous membrane material, expanded polytet rafluoroethylene (ePTFE), for culturing hepatocytes on its surface was examined. Adult rat hepatocytes were attached to an ePTFE surface and cultured in a hormonally defined medium supplemented with or without fetal calf serum (FCS, 10%) or bovine serum albumin (BSA, 0.03-3%). Wh en cultured in a FCS-suplemented medium, hepatocytes reorganized thems elves into multilayer cell aggregates on an ePTFE surface. The morphol ogical characteristics of hepatocytes were influenced by the modificat ion of the ePTFE surface as well as the culture medium. Hepatocytes cu ltured on a polyvinylalcohol (PVA)-coated ePTFE surface formed many mo re multilayer cell aggregates than those cultured on an uncoated ePTFE surface. Such highly multilayered hepatocyte aggregates were also not ed when the cells were cultivated in a BSA-supplemented medium. On the other hand, when cultured in a FCS- or BSA-free medium, hepatocytes f ormed cell monolayers on both PVA-coated and uncoated ePTFE surfaces a s did the cells on a collagen-coated polystyrene surface. The hepatocy tes in the aggregates exhibited high albumin expression capability and low DNA synthesis rate as compared with those in monolayer cultures. The multilayer hepatocyte aggregates, as immobilized on a PVA-coated e PTFE surface in a serum-supplemented medium, are shown to be not only morphologically, but functionally differentiated, and will provide us a model system for the development of a bioreactor using hepatocytes, particularly for a hybrid-type artificial liver.