Cytochrome P-450 1A1/1A2 induction, albumin secretion, and histological changes in cultured rat liver slices

The objective of this study was to characterize precision-cut rat liver slices for maintenance of selected differentiated functions with time in culture. We investigated protein and DNA content, cytochrome P-450 1A1/1A2 activity and, mRNA levels, albumin secretion and mRNA levels, and histology in slices cultured up to 96 h in serum-free Chee's essential medium supplemented with insulin, transferrin, selenium, dexamethasone, and epidermal growth factor. Slices were cultured in 12-well plates on a rotating shaker at 37°C in air-CO₂ (95:5%). After an initial decrease, slice protein content remained relatively constant whereas DNA content decreased progressively with time in culture. Basal Cyp 1A1/1A2 activity, measured by the metabolism of 7-ethoxyresorufin (EROD) in the slice homogenates, was maintained through 96 h. Induction of EROD activity by β-napthoflavone was first detected after 48 h and was maximal at 96 h. A similar pattern of induction was observed for CYP 1A1 mRNA. After an initial decrease, albumin secretion and mRNA levels remained stable. However, in spite of their functional viability, the histology of the slices revealed extensive degeneration accompanied by the progressive appearance of a peripheral layer of hypertrophic/hyperbasophilic hepatocytes. These results indicate that these culture conditions are not suitable for prolonged culture of liver slices. Efforts are in progress to optimize culture conditions so that slices maintain normal morphology as well as function.