In Vivo Estimation of Bioartificial Liver with Recombinant HepG2 Cells Using Pigs with Ischemic Liver Failure

Biological efficacy of a recombinant human hepatic cell line, glutamine synthetase transfected HepG2 (GS-HepG2), was examined with large-scale culture in a circulatory flow bioreactor and in pigs with ischemic liver failure. GS-HepG2 cells were cultured in a circulatory flow bioreactor from 5 × 107 to 4 × 109 cells for 109 days. The cells showed ammonia removal activity even under substrate (glutamic acid)-free medium, suggesting that the GS catalyzed the activity using intracellular glutamic acid that had been pooled during conventional culture. When GS-HepG2 bioartificial liver (BAL) was applied to pigs with ischemic liver failure, survival time was prolonged to 18.8 ± 6.1 h (mean ± SD, n = 4) from 13.8 ± 5.4 h (n = 6) and 10.7 ± 4.1 h (n = 6) (groups treated with cell-free BAL and treated with plasma exchange and continuous hemodia-filtration, respectively). Laboratory data indicated the tendency for improvement in increase of blood ammonia level and decline of blood coagulation indices in the GS-HepG2 BAL-treated group. The advantages and potential for the cell line as a bioreactor in BAL is also discussed, comparing to those of isolated porcine hepatocytes.