Human Pharmacogenetics and Human Liver Regeneration

描述（由申请人提供）：我们已经开发了一种用于产生具有完全成熟和功能性人肝组织的嵌合小鼠的新方法，该嵌合小鼠在没有任何正在进行的肝脏病理学并且没有持续的药物治疗的情况下得以维持。该模型系统克服了显著限制现有模型的实用性的实质性问题（肾脏和肝脏病理学、短寿命、不完全的肝脏替代）。为了做到这一点，一个高度免疫功能低下（NOG）的小鼠基因工程表达胸苷激酶转基因在肝脏中，这使得时间控制和组织特异性消融小鼠肝组织后，无毒药物（更昔洛韦）管理。在注射人肝细胞后，受体小鼠显示具有高水平的原位人肝重建，其存活时间比在任何其他模型中可以达到的更长（>8个月）;并且具有成熟人肝的基因表达谱和三维结构特征。首先，该平台将用于开发新的移植方法，使人类肝脏干细胞，人类诱导多能上皮细胞（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，这将使终末期肝病治疗的范式完全转变：“肝移植”可以使用自体细胞进行，而无需免疫抑制。其次，通过对供体人肝细胞进行基因分型，将产生一组具有“人源化肝脏”的小鼠，其具有用于I期药物代谢的特定等位基因。然后，将分析至少3种药物（其代谢依赖于人CYP 450酶活性）的人特异性药物代谢产物的形成速率。如果成功的话，这种创新的模型系统将使药物遗传学分析能够在完全人类的背景下在体内有效地进行，控制所有混杂的环境变量，这将克服表征药物代谢个体间变异的重大障碍。 公共卫生相关性：该项目将从祖细胞中原位产生具有人类肝脏的嵌合小鼠。如果成功，这一革命性的实验平台将使：“肝移植”能够使用自体细胞进行，而无需免疫抑制;并将为人类药物遗传学分析提供一个革命性的平台，这将克服理解药物代谢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. PUBLIC HEALTH RELEVANCE: This project will produce chimeric mice with human livers in situ from progenitor cells. If successful, this revolutionary experimental platform will enable: 'liver transplantation' to be performed using autologous cells without immunosuppression; and will provide a revolutionary platform for human pharmacogenetic analysis, which will overcome a significant roadblock for understanding inter-individual variation in drug metabolism.