In Vivo Induction of Human Cytochrome P450 Enzymes Expressed in Chimeric Mice With Humanized Liver

Katoh, Miki; Matsui, Tomohito; Nakajima, Miki; Tateno, Chise; Soeno, Yoshinori; Horie, Tetsuhiro; Iwasaki, Katsunori; Yoshizato, Katsutoshi; Yokoi, Tsuyoshi

doi:10.1124/dmd.104.002600

Cited by 54 publications

(45 citation statements)

References 31 publications

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“…Many recent publications have unambiguously demonstrated the value of humanized mouse livers for the study of drug metabolism and hepatitis research [7][8][9]21,[23][24][25][26][27][28][29] . However, the albumin-uPA transgenic mouse used for these studies has several major practical limitations.…”

Section: Discussionmentioning

confidence: 99%

Robust expansion of human hepatocytes in Fah−/−/Rag2−/−/Il2rg−/− mice

et al. 2007

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Mice that could be highly repopulated with human hepatocytes would have many potential uses in drug development and research applications. The best available model of liver humanization, the uroplasminogen-activator transgenic model, has major practical limitations. To provide a broadly useful hepatic xenorepopulation system, we generated severely immunodeficient, fumarylacetoacetate hydrolase (Fah)-deficient mice. After pretreatment with a urokinaseexpressing adenovirus, these animals could be highly engrafted (up to 90%) with human hepatocytes from multiple sources, including liver biopsies. Furthermore, human cells could be serially transplanted from primary donors and repopulate the liver for at least four sequential rounds. The expanded cells displayed typical human drug metabolism. This system provides a robust platform to produce high-quality human hepatocytes for tissue culture. It may also be useful for testing the toxicity of drug metabolites and for evaluating pathogens dependent on human liver cells for replication.The liver is the principal site for the metabolism of xenobiotic compounds, including medical drugs. Because many hepatic enzymes are species specific, it is necessary to evaluate the metabolism of candidate pharmaceuticals using cultured primary human hepatocytes 1,2 . Today, hepatocytes are isolated primarily from cadaveric organs and then shipped to the location where testing will be performed. The condition (viability and state of differentiation) of hepatocytes from cadaveric sources is highly variable, and many cell preparations are of marginal quality. The availability of high-quality human hepatocytes is further hampered by the fact that they cannot be substantially expanded in tissue culture 3,4 . Hepatocytes from readily available mammalian species, such as the mouse, are not suitable for drug testing because they have a different complement of metabolic enzymes and

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Section: Discussionmentioning

confidence: 99%

Robust expansion of human hepatocytes in Fah−/−/Rag2−/−/Il2rg−/− mice

et al. 2007

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“…Katoh et al (2004Katoh et al ( , 2005a reported that cytochrome P450 (P450) isoforms and phase II enzymes in chimeric mice in which the human hepatocyte replacement rate was nearly 90% were almost the same as those in human liver, based on quantitation of enzyme proteins. They also showed that the chimeric mice are a useful animal model to estimate the inductive effect on P450 in humans (Katoh et al, 2005b). We have shown that aldehyde oxidase, a cytosolic drugmetabolizing enzyme, in chimeric mice has functional characteristics almost identical to those of human aldehyde oxidase (Kitamura et al, 2008).…”

mentioning

confidence: 82%

CYP2C9-Catalyzed Metabolism ofS-Warfarin to 7-Hydroxywarfarin in Vivo and in Vitro in Chimeric Mice with Humanized Liver

Inoue¹,

Nitta²,

Sugihara³

et al. 2008

Drug Metab Dispos

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ABSTRACT:Chimeric mice having humanized livers were constructed by transplantation of human hepatocytes. In this study, we investigated whether these mice have a capacity for drug metabolism similar to that of humans by examining hydroxylation of S-warfarin, which is predominantly metabolized to S-7-hydroxywarfarin, catalyzed by CYP2C9, in humans but not mice. The 7-hydroxylating activity of chimeric mouse liver microsomes toward S-warfarin was approximately 10-fold higher than that of control (urokinase-type plasminogen activator-transgenic severe combined immunodeficient) mice. The 7-hydroxylase activity of chimeric mouse liver microsomes was markedly inhibited by sulfaphenazole, as was that of human liver microsomes, whereas the activity of control mice was unaffected. The CYP2C isoform in chimeric mouse liver was also confirmed to be the human isoform, CYP2C9, by immunoblot analysis. In the present in vivo study, the level of S-7-hydroxywarfarin in plasma of chimeric mice was approximately 7-fold higher than that in control mice, in agreement with the in vitro data. Thus, the CYP2C isoform in chimeric mice functions in vivo and in vitro as a human isoform, CYP2C9. These results suggest that chimeric mice with humanized liver could be useful for predicting drug metabolism in humans, at least regarding CYP2C9-dependent metabolism.Chimeric mice have been constructed by transplantation of human hepatocytes into urokinase-type plasminogen activator-transgenic severe combined immunodeficient mice (Dandri et al., 2001;Mercer et al., 2001). It was suggested that these chimeric mice may be useful as an in vivo model for studies on human liver diseases and hepatotropic viruses. Prolonged infections with human hepatitis B or C virus can be maintained in these mice (Dandri et al., 2001;Mercer et al., 2001). However, the chimeric mice used in those experiments did not have a high level of replacement with human hepatocytes. In a recent study, Tateno et al. (2004) prepared chimeric mice in which the liver was almost completely repopulated with human hepatocytes. Furthermore, they reported that cytochrome P450 subtypes in liver microsomes of chimeric mice in which more than 80% of hepatocytes had been replaced with human hepatocytes were similar to those of the donor human liver . Therefore, the chimeric mice constructed by Tateno et al. (2004) appear to be an excellent in vivo model for prediction of drug metabolism and drug-drug interactions due to drug induction and inhibition of drugmetabolizing enzymes in humans. Katoh et al. (2004Katoh et al. ( , 2005a reported that cytochrome P450 (P450) isoforms and phase II enzymes in chimeric mice in which the human hepatocyte replacement rate was nearly 90% were almost the same as those in human liver, based on quantitation of enzyme proteins. They also showed that the chimeric mice are a useful animal model to estimate the inductive effect on P450 in humans (Katoh et al., 2005b). We have shown that aldehyde oxidase, a cytosolic drugmetabolizing enzyme, in chimeric mice has func...

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“…Assays such as the transactivation and immortalized hepatocyte assays are extremely high throughput, however they lack the complexity of human hepatocytes which represent the multitude of transcription factors/receptors and their interactions and dynamic drug exposure which occurs in patients were developed by injecting human hepatocytes into SCID mice (80% of the hepatocytes in the liver were of human origin) (67). CYP1A1/2 and CYP3A4 mRNA, protein content, and enzyme activity have been shown to be induced in chimeric mice treated with known human inducers and in hepatocytes isolated from humanized chimeric mice (68)(69)(70).…”

Section: Transgenic/chimeric Animalsmentioning

confidence: 99%

Current Industrial Practices in Assessing CYP450 Enzyme Induction: Preclinical and Clinical

Sinz

Wallace

Sahi³

2008

AAPS J

114

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Abstract. Induction of drug metabolizing enzymes, such as the cytochromes P450 (CYP) is known to cause drug-drug interactions due to increased elimination of co-administered drugs. This increased elimination may lead to significant reduction or complete loss of efficacy of the co-administered drug. Due to the significance of such drug interactions, many pharmaceutical companies employ screening and characterization models which predict CYP enzyme induction to avoid or attenuate the potential for drug interactions with new drug candidates. The most common mechanism of CYP induction is transcriptional gene activation. Activation is mediated by nuclear receptors, such as AhR, CAR, and PXR that function as transcription factors. Early high throughput screening models utilize these nuclear hormone receptors in ligand binding or cell-based transactivation/reporter assays. In addition, immortalized hepatocyte cell lines can be used to assess enzyme induction of specific drug metabolizing enzymes. Cultured primary human hepatocytes, the best established in vitro model for predicting enzyme induction and most accepted by regulatory agencies, is the predominant assay used to evaluate induction of a wide variety of drug metabolizing enzymes. These in vitro models are able to appropriately predict enzyme induction in patients when compared to clinical drug-drug interactions. Finally, transgenic animal models and the cynomolgus monkey have also been shown to recapitulate human enzyme induction and may be appropriate in vivo animal models for predicting human drug interactions.

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In Vivo Induction of Human Cytochrome P450 Enzymes Expressed in Chimeric Mice With Humanized Liver

Cited by 54 publications

References 31 publications

Robust expansion of human hepatocytes in Fah−/−/Rag2−/−/Il2rg−/− mice

Robust expansion of human hepatocytes in Fah−/−/Rag2−/−/Il2rg−/− mice

CYP2C9-Catalyzed Metabolism ofS-Warfarin to 7-Hydroxywarfarin in Vivo and in Vitro in Chimeric Mice with Humanized Liver

Current Industrial Practices in Assessing CYP450 Enzyme Induction: Preclinical and Clinical

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