Abstract
We developed murine Cyp3a knockout (KO) chimeric mice with humanized liver expressing human P450s similar to those in humans and whose livers and small intestines do not express murine Cyp3a. This approach may overcome effects of residual mouse metabolic enzymes like Cyp3a in conventional chimeric mice with humanized liver, such as PXB-mice [urokinase plasminogen activator/severe combined immunodeficiency (uPA/SCID) mice repopulated with over 70% human hepatocytes] to improve the prediction of drug metabolism and pharmacokinetics in humans. After human hepatocytes were transplanted into Cyp3a KO/uPA/SCID host mice, human albumin levels logarithmically increased until approximately 60 days after transplantation, findings similar to those in PXB-mice. Quantitative real-time–polymerase chain reaction analyses showed that hepatic human P450s, UGTs, SULTs, and transporters mRNA expression levels in Cyp3a KO chimeric mice were also similar to those in PXB-mice and confirmed the absence of Cyp3a11 mRNA expression in mouse liver and intestine. Findings for midazolam and triazolam metabolic activities in liver microsomes were comparable between Cyp3a KO chimeric mice and PXB-mice. In contrast, these activities in the intestine of Cyp3a KO chimeric mice were attenuated compared with PXB-mice. Owing to the knockout of murine Cyp3a, hepatic Cyp2b10 and 2c55 mRNA levels in Cyp3a KO/uPA/SCID mice (without hepatocyte transplants) were 8.4- and 61-fold upregulated compared with PXB-mice, respectively. However, human hepatocyte transplantation successfully restored Cyp2b10 level nearly fully and Cyp2c55 level partly (still 13-fold upregulated) compared with those in PXB-mice. Intestinal Cyp2b10 and 2c55 were also repressed by human hepatocyte transplantation in Cyp3a KO chimeric mice.
Footnotes
- Received January 22, 2015.
- Accepted May 15, 2015.
Current affiliations:
↵1 Analysis and Pharmacokinetics Research Laboratories, Drug Discovery Research, Astellas Pharma Inc. 2-1-6, Kashima, Yodogawa-ku, Osaka City, Osaka 532-8514, Japan.
↵2 Department of Biomedical Science, Institute of Regenerative Medicine and Biofunction, Graduate School of Medical Science, and Chromosome Engineering Research Center, Tottori University, 86, Nishi-cho, Yonago City, Tottori 683-8503, Japan.
↵3 ADME and Tox Research Institute, Sekisui Medical Co., Ltd., 13-5, Nihonbashi 3-chome, Chuo-ku, Tokyo 103-0027, Japan.
↵4 PhoenixBio Co., Ltd., 3-4-1, Kagamiyama, Higashi-Hiroshima City, Hiroshima 739-0046, Japan.
↵5 Liver Research Project Center, Hiroshima University, 1-2-3, Kasumi, Minami-ku, Hiroshima City, Hiroshima 734-8551, Japan.
- Copyright © 2015 by The American Society for Pharmacology and Experimental Therapeutics
DMD articles become freely available 12 months after publication, and remain freely available for 5 years.Non-open access articles that fall outside this five year window are available only to institutional subscribers and current ASPET members, or through the article purchase feature at the bottom of the page.
|