CYTOTOXICITY OF BILE IN HUMAN HEP G2 CELLS AND IN PRIMARY CULTURES OFRAT HEPATOCYTES

There has been increasing interest in the development of a hepatocyte bioreactor for the treatment of acute hepatic failure; however, little is known about the effect of hepatocyte byproducts on the viability o f the cells in the bioreactor environment. We investigated the effects of increasing concentrations of bile on the growth and viability of t he human hepatoma cell line Hep G2 and on the cytochrome P-450 content and dependent mixed function oxidase (MFO) activities, reduced glutat hione (GSH) content, and glutathione S-transferase (GST) activity of p rimary cultures of rat hepatocytes. Our purpose was to determine wheth er or not it would be necessary to pretreat the plasma from patients w ith acute liver failure to remove elevated bile concentrations which m ight be toxic to the hepatocytes in an artificial liver device. Bile w as found to inhibit Hep G2 cell growth at concentrations as low as 0.1 % and to decrease viability at concentrations above 0.5%. The cytochro me P-450 and GSH contents and the activities of the MFO system and of GST were decreased in the primary cultures of hepatocytes following 24 h treatment with concentrations of bile at and above 0.5%. The MFO ac tivities associated with different cytochrome P-450 isoenzymes decreas ed to different extents in the presence of bile with the O-dealkylatio n of pentoxyresorufin being more labile than that of ethoxyresorufin. Our data indicate that elevated bile concentrations are cytotoxic to l iver cells, and it may be necessary to pretreat patient plasma to decr ease its bile content to protect the cells during the clinical operati on of a hepatocyte bioreactor device.