Primary hepatocytes outperform Hep G2 cells as the source of biotransformation functions in a bioartificial liver

Objective: Metabolic activity of transformed human liver (Hep G2) cells and primary-rat hepatocytes were compared during in vitro application of a gel entrapment bioartificial liver. Background: Clinical trials of bioartificial liver devices containing either transformed liver cells or primary hepatocytes have been initiated. A study comparing transformed liver cells and primary hepatocytes in a bioartificial liver under similar conditions has not been reported previously. Methods: Gel entrapment bioartificial liver devices were inoculated with 100 million cells, Hep G2 cell line (n = 4), or rat hepatocytes (n = 16), and studied for up to 60 days of in vitro cultivation. Results: Hep G2 cells grew to confluence within the gel entrapment configuration with a doubling time of 20 ± 3 hours. Rat hepatocytes significantly outperformed Hep G2 cells at confluence in all categories of biotransformation, including ureagenesis (3.5 ± 0.7 vs. 0.3 ± 0.1 μmol/hr, p < 0.05), glucuronidation (630 ± 75 vs. 21 ± 2 nmol/hr, p < 0.005), sulfation (59 ± 13 vs. 5 ± 2 nmol/hr, p < 0.05), and oxidation (233 ± 38 vs. < 1 nmol/hr, p < 0.005). At the conclusion of one experiment, Hep G2 cells were found in the extracapillary compartment of the bioartificial liver, analogous to the patient's compartment during clinical application. Conclusions: Primary rat hepatocytes were superior to the Hep G2 cell line as the source of hepatic function in a bioartificial liver and avoided the potential risk of tumor transmigration from the bioartificial liver into the patient's circulation.