INFLUENCE OF THE ISOLATION METHOD ON THE STABILITY OF DIFFERENTIATED PHENOTYPE IN CULTURED RAT HEPATOCYTES

Primary cultures of adult rat hepatocytes were established using two different isolation procedures: a two-step collagenase perfusion and a method using ethylenediaminetetraacetate (EDTA) as the dissociating agent. Both techniques provided good yields of hepatocytes with comparable viability. The evolution of hepato-specific protein levels and several drug-metabolizing enzyme activities were followed for 8 days in cultured hepatocytes obtained by both methods. EDTA-isolated hepatocytes maintained a low gamma glutamyltransferase (GGT) activity, whereas collagenase-treated cells acquired a high GGT level. Transferrin secretion and tyrosine aminotransferase (TAT), alanine aminotransferase (ALT), and microsomal epoxide hydrolase (mEH) activities were stable in both EDTA- and collagenase-isolated hepatocytes, whereas albumin secretion, aspartate amino transferase (AST) activity, total cytochromes P-450 content, IA1 and IIB1 P-450 isoenzymes, NADPH-cytochrome P-450 reductase (EC 1.6.2.4) levels, and bilirubin glucuronidation decreased faster in collagenase-treated cells. The most important difference observed was the maintainance of the mixed-function oxidase system in EDTA-isolated hepatocytes. These results emphasize the critical role of isolation technique in stabilization of differentiated hepatocytes in primary culture.