Differentiating Human ESC Towards Hepatocytes

描述（由申请人提供）：原位肝移植（奥尔特）治疗肝病具有相当高的发病率和死亡率。此外，由于器官短缺，每年有数千人在没有得到移植的情况下死亡。因此，更安全，更方便的替代疗法将使许多需要肝移植的人受益。一种可能解决这个问题的方法是开发一种表达肝脏特异性基因的增殖细胞系，该细胞系可用于细胞移植或生物人工肝。从人类胚胎干细胞（hESC）中开发这样一个细胞系也将为药理学和毒理学研究提供有价值的细胞。具体目标：1）确定体外指导hESC分化成肝细胞的条件; 2）表征分化的hESC; 3）在NOD-SCID小鼠中建立hESC的体内潜力;和4）在非人灵长类动物中建立hESC的体内潜力。研究方法：将根据经验测定各种条件以描绘使hESC沿着肝细胞谱系分化的最有效方法。这将包括优化培养基，细胞外基质和生长因子的经验性研究。肝特异性慢病毒载体的转导将提高细胞的纯度。纯化的细胞将通过肝脏特异性基因产物、生长因子反应性和潜在致癌性的测定来表征。为了确定细胞是否可以在移植后植入、增殖和发挥功能，将在肝细胞损伤的免疫缺陷NOD-SCID小鼠模型和非人灵长类动物中进行研究。将利用创新的成像方法来评估体内细胞随时间的活力和增殖。健康相关性：如果研究成功进行，它将为开发可用于毒理学和药理学研究的分化的人肝细胞的无限来源提供条件，并可用于人类的细胞治疗。

DESCRIPTION (provided by applicant): Treatment of liver disease with orthotopic liver transplantation (OLT) carries considerable morbidity and mortality. Moreover, due to organ shortages, thousands of people die each year without getting transplanted. Therefore, safer and more convenient alternative therapies will benefit many people requiring liver transplantation. An approach that might address this problem is the development of a proliferative cell line that expresses liver-specific genes which could be employed for cell transplantation or for a bioartificial liver. Developing such a line from human embryonic stem cells (hESC) would also provide cells valuable for pharmacology and toxicology studies. Specific Aims: 1) to determine conditions for directing the hESC to differentiate into hepatocytes in vitro; 2) to characterize the differentiated hESC; 3) to establish the in vivo potential of hESC in NOD-SCID mice; and 4) to establish the in vivo potential or hESC in nonhuman primates. Methods: A variety of conditions will be empirically assayed to delineate the most effective approach to differentiate the hESC along a hepatocyte lineage. This will include empiric studies of optimizing media, extracellular matrix, and growth factors. The purity of the cells will be enhanced with transduction of liver-specific lent virus vectors. The purified cells will be characterized with assays of liver-specific gene products, growth factor responsiveness, and potential oncogenicity. To determine whether the cells can engraft, proliferate, and function after transplantation, studies will be conducted in immunodeficient NOD- SCID mouse models of liver cell injury and in nonhuman primates. Innovative imaging approaches will be utilized to assess the viability and proliferation of the cells over time in vivo. Health Relatedness: If the studies are successfully undertaken, it will provide for the development of an unlimited source of differentiated human hepatocytes that can be used for toxicology and pharmacology studies, and can be employed in cell-based therapeutics in man.