Biochemical Functions and mRNA Expression of Rat Hepatocytes in a Bioartificial Liver Module

Evaluation of hepatic functions of the bioartificial liver (BAL) module is essential for developing an optimal BAL system which can be applied to a patient with fulminant hepatic failure. Although hepatic function in BALs has been evaluated only in biochemical activities in previous reports, we assessed a newly designed BAL from a hollow fiber type not only in biochemical activities such as gluconeogenesis, ureogenesis and albumin synthesis but also in the expressions of albumin messenger RNA (mRNA) and cytochrome P450 2B1 mRNA by Northern blot analysis. One to 3 × 108 hepatocytes isolated from adult rats were suspended in hydrated collagen, loaded into a hollow fiber module and perfused with L-15 medium supplemented with various hormones for 2 to 13 days. Both production rates of glucose and urea nitrogen were highest on day 1 (610 μg glucose/107 cells/h and 76.1 μg urea nitrogen/107 cells/h, respectively). Ureogenesis was maintained for 8 days in BAL, but gluconeogenesis decreased after 7 days. Albumin production rate increased to day 3, reached its maximum (11.0 μg/107 cells/h) and then gradually decreased. The expression of albumin mRNA was highest on day 2 and detectable until day 11. Cytochrome P450 2B1 mRNA was detected only on day 2. Northern blot analysis showed that the maintenance period in each hepatic function was different. These results suggested that assessment of the functions at a molecular level was invaluable in the development of a potential BAL for clinical use. It might be necessary to reconstruct the lobular system as well as a 3-dimensional environment for hepatocytes in the BAL to maintain the ability of detoxification such as cytochrome P450s.