Differentiating Human ESC Towards Hepatocytes

描述(由申请人提供)：原位肝移植(OLT)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。一种可能解决这一问题的方法是开发一种能够表达肝脏特异性基因的增殖性细胞系，这种基因可以用于细胞移植或生物人工肝。从人类胚胎干细胞(HESC)开发这样的株系也将提供对药理学和毒理学研究有价值的细胞。具体目的：1)确定体外诱导hESC分化为肝细胞的条件；2)鉴定分化后的hESC；3)建立hESC在NOD-SCID小鼠体内的潜能；4)建立非人灵长类动物的hESC体内潜能。方法：对各种条件进行经验性分析，以确定区分肝细胞系的hESC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研究。转导肝脏特异性Lent病毒载体将提高细胞的纯度。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瘤性的分析来表征。为了确定细胞在移植后是否能够植入、增殖和功能，将在免疫缺陷的NOD-SCID小鼠肝细胞损伤模型和非人类灵长类动物中进行研究。创新的成像方法将被用来评估细胞随着时间的推移在体内的存活和增殖。与健康相关：如果研究成功，它将提供无限来源的分化的人类肝细胞，可用于毒理学和药理学研究，并可用于人类的细胞疗法。

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.