Primary cultures of human hepatocytes but not HepG2 hepatoblastoma cells are suitable for the study of glycosidic conjugation of bile acids

To define the role of glycosidic conjugation of bile acids in humans, an in vitro model system is desirable. We studied the formation of glycosidic co njugates of bile acids in primary cultures of human hepatocytes, isolated f rom organ donor liver, and the human hepatoblastoma cell line, HepG2. Cells were incubated with 100 muM bile acids (chenodeoxycholic, CDCA; hyodeoxych olic, HDCA; and isoursodeoxycholic acids, isoUDCA) and 1-2 mM uridine dipho sphoglycosides (UDP-glucose, UDP-Glc; UDP-glucuronic acid, UDP-GlcA, and UD P-N-acetylglucosamine, UDP-GlcNAc), and octyl glucoside. Media were analyse d by electrospray-/gas chromatography-mass spectrometry and electrospray wi th collision induced dissociation. Primary cultures of human hepatocytes fo rmed glycosidic bile acid conjugates with UDP-sugars (6 alpha -Glc-HDCA, 6 alpha -GlcA-HDCA, and 7 beta -GlcNAc-isoUDCA) and octyl glucoside as sugar donors (3 alpha -Glc-CDCA). HDCA was completely metabolised to either Glc-H DCA, a compound yet not found in vivo, or GlcA-HDCA. No glycosidic bile aci d conjugate was found in media from experiments with HepG2. Thus, primary c ultures of human hepatocytes, but not HepG2, are suitable in vitro systems for the study of glycosidic bile acid conjugation reactions. (C) 2001 Elsev ier Science B.V. All rights reserved.