Maintenance of differentiated rat hepatocytes in primary culture.

Normal adult rat hepatocytes remained viable and functional for at least 43 days when plated on collagen-coated dishes and fed chemically defined medium supplemented with dimethyl sulfoxide (Me2SO). Hepatocytes isolated by collagenase perfusion and cultured in the presence or absence of Me2SO were (i) examined by light and electron microscopy for morphological changes; (ii) analyzed for the production of albumin and other plasma proteins; and (iii) tested by autoradiography for DNA synthesis. Me2SO-treated cells continued to produce specific plasma proteins during the entire culture period; albumin production was consistently high (11-19 micrograms/ml of culture medium per 24 hr) from day 2 to at least day 43 after plating. Ultrastructural analyses demonstrated that Me2SO-treated hepatocytes resembled those from intact liver in organization of cytoplasmic organelles and cellular junctions. The optimal concentration for observing the morphological and biochemical effects of Me2SO was 2% (vol/vol). We conclude that supplementation of chemically defined medium with Me2SO enables maintenance of differentiated hepatocytes in culture for extended periods of time.