Chimeric Mice with Humanized Livers: A Unique Tool for in Vivo and in Vitro Enzyme Induction Studies

Masakazu Kakuni,Chihiro Yamasaki,Chise Tateno,Yuji Ishida,Asato Tachibana,Yasumi Yoshizane

doi:10.3390/ijms15010058

Masakazu Kakuni, Chihiro Yamasaki + Show 4 more

Open Access

https://doi.org/10.3390/ijms15010058

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Abstract

We performed in vivo and in vitro studies to determine the induction of human cytochrome P450 (CYP) using chimeric mice with humanized liver (PXB-mice®) and human hepatocytes isolated from the PXB-mice (PXB-cells), which were derived from the same donor. For the in vivo study, PXB-mice were injected with 3-methylcholanthrene (3-MC, 2 or 20 mg/kg) or rifampicin (0.1 or 10 mg/kg) for four days. For the in vitro study, PXB-cells were incubated with 3-MC (10, 50, or 250 ng/mL) or with rifampicin (5 or 25 μg/mL). The CYP1A1 and 1A2, and CYP3A4 mRNA expression levels increased significantly in the PXB-mouse livers with 20 mg/kg of 3-MC (Cmax, 12.2 ng/mL), and 10 mg/kg rifampicin (Cmax, 6.9 μg/mL), respectively. The CYP1A1 mRNA expression level increased significantly in PXB-cells with 250 ng/mL of 3-MC, indicating lower sensitivity than in vivo. The CYP1A2 and CYP3A4 mRNA expression levels increased significantly with 50 ng/mL of 3-MC, and 5 μg/mL of rifampicin, respectively, which indicated that the sensitivities were similar between in vivo and in vitro studies. In conclusion, PXB-mice and PXB-cells provide a robust model as an intermediate between in vivo and in vitro human metabolic enzyme induction studies.

Highlights

Metabolic enzyme induction is a side effect of some drugs, and it can cause important problems in drug metabolism and toxicity, such as a reduction in a drug’s effect and an increase in reactive metabolites
In the liver of the chimeric mouse (PXB-mouse®) we developed, mouse hepatocytes are largely repopulated with the transplanted human hepatocytes, which have been demonstrated to express human cytochrome P450 (CYP) enzymes [3], phase II enzymes [4], and transporters [5], and have the potential for CYP enzyme induction with inducers [2]
In the in vivo study, a significant decrease in Area under the curves (AUCs) of 3-MC was induced by four days 3-MC administration (20 mg/kg), which was associated with a significant increase in hCYP1A1 mRNA expression and hCYP1A2 protein expression

Summary

Introduction

Metabolic enzyme induction is a side effect of some drugs, and it can cause important problems in drug metabolism and toxicity, such as a reduction in a drug’s effect and an increase in reactive metabolites. It is, necessary to evaluate the induction potential of drugs in humans during preclinical drug development. Necessary to evaluate the induction potential of drugs in humans during preclinical drug development Such predictions are difficult to test because there are species differences between humans and laboratory animals in metabolic enzyme inducibility. As treatment of the mice with inducers results in in vivo enzyme induction in the humanized hepatocytes, the animals chimeric mice enable the evaluation of enzyme inducing effects would be useful in predicting enzyme induction in humans

Results

Discussion

Conclusion