Z Gastroenterol 2009; 47 - P107
DOI: 10.1055/s-0029-1241358

Metaheps exhibit CYP P450 metabolism – induction by ethanol, phenytoin and dexamethasone

A Benesic 1, NL Rahm 1, S Ernst 1, E De Toni 1, M Escobar 1, V Gülberg 1, AL Gerbes 1
  • 1Medizinische Klinik II, Klinikum Großhadern, München, Germany

Aims: Considerable effort is aimed at the search for hepatocyte-like cells to use them in cell based therapies. Transformed peripheral monocytes have been described as a possible source of hepatocyte-like cells. In contrast to primary hepatocytes, monocytes are easy to isolate and available. Since primary hepatocytes loose functional CYP P450-metabolism after few days in culture, hepatocytoid cells with a stable and functional CYP P450 metabolism could markedly improve in vitro toxicology studies and decrease the need for animal testing.

Aim of the study: Investigation of drug metabolism in monocyte derived hepatocytoid cells.

Methods: Peripheral monocytes of healthy donors were cultured by a self-established protocol. CYP P450 metabolism in these cells (Metaheps) was assayed indirectly by acetaminophen (APAP) induced LDH-release and ALT-release as well as using a luciferin-based CYP3A4 assay after incubation of cells with the inducers dexamethasone and phenytoin.

Results: After incubation with APAP monocyte derived cells displayed a time- and dose-dependent toxicity. This effect could be enhanced by preconditioning with the CYP2E1- inducer ethanol (0.05–0.2%) and inhibited by N-Ac. Incubation with the CYP3A4 inducers dexamethasone and phenytoin lead to an increase in CYP3A4-activity of 316±55% (dexamethasone 10µM, 48h) and 191±20% (phenytoin 10µM, 48h), respectively.

Discussion: We here provide evidence for a functional CYP P450 activity in monocyte derived hepatocytoid cells. The cells display APAP-toxicity as indirect evidence for CYP2E1-metabolism. This is further corroborated by enhanced toxicity after CYP2E1-induction by ethanol. CYP3A4 activity could be induced in a time- and dose-dependent manner using prototypic inducers. The CYP-metabolism in these cells was detectable for at least 21 days in culture.

Conclusions: Metaheps could serve as an important new tool for in vitro toxicity studies since they display:

  • a hepatocyte-like response to toxic APAP-effects that is inhibited by N-acetylcysteine

  • indirect evidence for ethanol-inducible CYP2E1 activity

  • direct evidence for CYP 3A4 activity inducible by prototypic substances

  • Functional CYP-activities that were detectable over at least 21 days in culture.