Received for publication January 20, 2006.
Revised November 3, 2006.
Accepted for publication November 7, 2006.

UTILITY OF LONG-TERM CULTURED HUMAN HEPATOCYTES AS AN IN VITRO MODEL FOR CYTOCHROME P450 INDUCTION

Abstract

Cytochrome P450 induction may have considerable implications for drug therapy. Therefore, understanding the induction potential of a new chemical entity at an early stage in discovery is crucial to reduce the risk of failure in the clinic and help the identification of non-inducing chemical structures. Availability of human viable tissue often limits evaluation of induction potential in human hepatocytes. A solution is to increase the time period during which the hepatocytes remain viable. In this study we have investigated the induction of several CYP isozymes in long term cultured hepatocytes compared with short term cultured hepatocytes from the same individuals. Short and long-term cultured primary hepatocytes isolated from each individual were cultured on a 96-well format and treated for 24 hours with a range of prototypical CYP inducers and Merck Research Laboratories (MRL) compounds. CYP3A4, 1A1, 1A2, 2B6 and 2C9 mRNA levels were measured using quantitative real-time reverse transcriptase-polymerase chain reaction (TaqMan) from the same cultured hepatocyte wells. CYP3A4, 1A1, 1A2, 2B6 and 2C9 were shown to be inducible in long term cultured hepatocytes. The fold induction varied between donors, and between short and long term cultured hepatocytes from the same donor. However, this variability can be controlled by normalising data from each hepatocyte preparation to a positive control. The use of long term cultured hepatocytes on 96-well plates has proven to be sensitive, robust and convenient for assessing CYP induction potential of new compound entities during drug discovery process.

Key words: CYP induction, hepatocytes, high throughput screening, human CYP enzymes

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