Evaluation of a flat membrane hepatocyte bioreactor for pharmacotoxicological applications:: Evidence that inhibition of spontaneously produced nitric oxide improves cell functionality

A laboratory-scale bioreactor was re-evaluated, with the aim of improving its use for the perfused culture of rat hepatocytes. In contrast to conventional culture systems, the flat membrane bioreactor (FMB) showed good functionality and biochemical competence during 2-3 days. Hepatocytes cultured in the FMB, specifically in a "sandwich" configuration, were functionally stable, as shown by a high rate of urea biosynthesis after challenge with NH4Cl, a low alanine-aminotransferase leakage and suppressed spontaneous nitric oxide (NO) production. Moreover, the time-course of the disappearance of cyclosporin A (CsA) from the perfusate demonstrated the high biotransformation capacity of cells in the FMB. The effect of CsA on the modulation of urea and spontaneous NO production demonstrated flexibility, in that minor changes could be observed at diverse time intervals and in a non-destructive way. The monitoring of nitrite levels during various steps of isolation and culture suggested that spontaneously produced NO has a negative impact on hepatocyte metabolic and functional integrity. In spite of the sophisticated techniques that are being used for the preparation of bioreactors, with hepatocytes surviving for longer periods, our data have shed light on some factors that could be important for the successful use of similar models for pharmacotoxicological and other biomedical applications.