Liver Engineering Laboratory, Department of Applied Research for Laboratory Animals, Central Institute for Experimental Animals (CIEA), 3-25-12 Tonomachi, Kawasaki-ku, Kawasaki, 210-0821, Japan.
Chromosome Engineering Research Center (CERC), Tottori University, Yonago, Japan.
Sci Rep. 2022 Sep 1;12(1):14907. doi: 10.1038/s41598-022-19242-0.
Chimeric TK-NOG mice with a humanized liver (normal Hu-liver) are a unique animal model for predicting drug metabolism in humans. However, residual mouse hepatocytes occasionally prevent the precise evaluation of human drug metabolism. Herein, we developed a novel humanized liver TK-NOG mouse with a conditional knockout of liver-specific cytochrome P450 oxidoreductase (POR cKO Hu-liver). Immunohistochemical analysis revealed only a few POR-expressing cells around the portal vein in POR cKO mouse livers. NADPH-cytochrome c reductase and cytochrome P450 (P450)-mediated drug oxidation activity in liver microsomes from POR cKO mice was negligible. After the intravenous administration of S-warfarin, high circulating and urinary levels of S-7-hydroxywarfarin (a major human metabolite) were observed in POR cKO Hu-liver mice. Notably, the circulating and urinary levels of S-4'-hydroxywarfarin (a major warfarin metabolite in mice) were much lower in POR cKO Hu-liver mice than in normal Hu-liver mice. POR cKO Hu-liver mice with minimal interference from mouse hepatic P450 oxidation activity are a valuable model for predicting human drug metabolism.
具有人源化肝脏（正常 Hu-liver）的嵌合 TK-NOG 小鼠是预测人类药物代谢的独特动物模型。然而，残留的小鼠肝细胞偶尔会妨碍对人类药物代谢的精确评估。在此，我们开发了一种新型的人源化肝脏 TK-NOG 小鼠，其肝脏特异性细胞色素 P450 氧化还原酶（POR）被条件性敲除（POR cKO Hu-liver）。免疫组织化学分析显示，POR cKO 小鼠肝脏门静脉周围只有少数 POR 表达细胞。POR cKO 小鼠肝微粒体中 NADPH-细胞色素 c 还原酶和细胞色素 P450（P450）介导的药物氧化活性可忽略不计。在静脉注射 S-华法林后，POR cKO Hu-liver 小鼠的 S-7-羟基华法林（一种主要的人类代谢物）的循环和尿中水平较高。值得注意的是，POR cKO Hu-liver 小鼠的 S-4'-羟基华法林（小鼠中主要的华法林代谢物）的循环和尿中水平远低于正常 Hu-liver 小鼠。POR cKO Hu-liver 小鼠的小鼠肝 P450 氧化活性干扰最小，是预测人类药物代谢的有价值模型。
