我们前期研究提示，胚胎干细胞（ESCs）向肝脏方向分化中，细胞1型上皮间质转化（1-EMT）水平过快是分化肝细胞呈单细胞状态而不能形成肝脏组织结构的主要原因。最近表明，体内以细胞自分泌蛋白调节Wnt/β-catenin信号进而调控1-EMT于稳定水平以维持机体组织的稳定性。我们预实验发现ESCs分化中Wnt/β-catenin信号抑制后，可降低细胞1-EMT水平并使其保持三维状态生长，提示可能有促进组织形成的作用，但进一步效果及机制不明。为此，本课题拟：①利用细胞自分泌蛋白sFRP-1等抑制Wnt/β-catenin信号，降低1-EMT以促进ESCs向肝脏组织结构分化；②研究其中β-catenin通过影响Snail等表达而调控1-EMT的机制，以及调控肝实质、间质细胞同步分化和增强细胞黏附而促进肝组织形成的机制。本课题旨在获得一种更高水平的肝功能替代物，并促进ESCs分化机制的完善和更新。

Until now, the hepatic differentiation of embryonic stem cells (ESCs) usually results in single cell lineage and could not form liver tissues. It is found that the too fast type 1 epithelial-mesenchymal transition (1-EMT) in late stage of ESCs differentiation is the major reason. 1-EMT is regulated by Wnt/β-catenin signal in normal tissues. However, recent studies showed that cellular autocrine signal can maintain a stable Wnt/β-catenin balance, and then regulate the stability of 1-EMT in vivo. Recently, we found that Wnt/β-catenin and 1-EMT levels decreased and then the differentiating hepatocytes can form a 3D status with vessel structures in a E-cad high expressed ESCs differentiation system. However, its mechanism is still unclear. We therefore want to use sFRP-1 in a in vitro ESCs differentiation system to mimic the in vivo cellular autocrine signal, which inhibits Wnt/β-catenin and dynamically regulates 1-EMT and then promotes hepatic tissue differentiation. Furthermore, we hope to find the regular patterns and evidences that Wnt/β-catenin mediated 1-EMT promotes ESCs to differentiate into hepatic tissue, and then obtain a new liver function substitute and a theory update in ESCs differentiation mechanisms.