Human Pharmacogenetics and Human Liver Regeneration

描述(申请人提供)：我们已经开发出一种新的方法来制造具有完全成熟和功能的人肝组织的嵌合小鼠，这种方法在没有任何正在进行的肝脏病理和不需要继续药物治疗的情况下保持不变。该模型系统克服了严重限制现有模型应用的实质性问题(肾脏和肝脏病理、寿命短、肝脏置换不全)。为此，对高度免疫受损(NOG)小鼠进行了基因工程，使其在肝脏中表达胸苷激酶转基因，这使得在给予无毒药物(更昔洛韦)后，能够对小鼠的肝组织进行时间控制和组织特异性的消融。在注射人肝细胞后，受体小鼠显示出高水平的人肝原位重建，存活时间比任何其他模型都要长(&gt；8个月)；并具有成熟人类肝脏的基因表达谱和三维结构特征。首先，这个平台将被用来开发新的移植方法，使人类肝脏干细胞、人类诱导的多能上皮细胞(HIPS)或人类脂肪细胞来源的干细胞能够重建人类肝脏。如果成功，这将使治疗终末期肝病的范式发生彻底转变：可以在没有免疫抑制的情况下使用自体细胞进行肝移植。其次，通过对捐赠者的肝细胞进行基因分型，将产生一组拥有具有I期药物代谢特定等位基因的人性化肝脏的小鼠。然后，将分析至少3种药物的人类特异性药物代谢物的形成速度，这些药物的代谢依赖于人类细胞色素P450酶的活性。如果成功，这一创新的模型系统将使药物遗传学分析能够在完全人类的活体范围内有效地进行，并控制所有混淆的环境变量，这将克服表征药物代谢的个体间差异的重大障碍。

DESCRIPTION (provided by applicant): We have developed a novel method for producing chimeric mice with fully mature and functional human liver tissue, which is maintained in the absence of any ongoing liver pathology and without continued drug treatment. This model system overcomes the substantial problems (kidney and liver pathology, short lifespan, incomplete liver replacement) that have significantly limited the utility of existing models. To do this, a highly immunocompromised (NOG) mouse was genetically engineered to express a thymidine kinase transgene in the liver, which enabled the temporally controlled and tissue-specific ablation of mouse liver tissue after administration of a non-toxic drug (gancyclovir). After injection of human liver cells, the recipient mice were shown to have a high level of human liver reconstitution in situ, which survived for a more prolonged period (>8 months) than could be attained in any other model; and to have a gene expression profile and 3-dimensional architecture characteristic of mature human liver. First, this platform will be used to develop novel transplantation methods that enable human liver stem cells, human induced pluripotent epithelial cells (hiPS), or human adipocyte-derived stem cells to reconstitute a human liver. If successful, this would enable a complete paradigm-shift for treatment of end-stage liver disease: 'liver transplantation' could be performed using autologous cells without immunosuppression. Secondly, by genotyping the donor human liver cells, a panel of mice with 'humanized livers' with specified alleles for phase I drug metabolizing will be produced. Then, the rate of formation of human-specific drug metabolites for at least 3 drugs, whose metabolism is dependent upon human CYP450 enzyme activity, will be analyzed. If successful, this innovative model system will enable pharmacogenetic analyses to be efficiently performed within an entirely human context in vivo with all confounding environmental variables controlled, which would overcome a significant roadblock for characterizing inter-individual variation in drug metabolism.