Asahina Kinji, Fujimori Hiroaki, Shimizu-Saito Keiko, Kumashiro Yuji, Okamura Kentaro, Tanaka Yujiro, Teramoto Kenichi, Arii Shigeki, Teraoka Hirobumi
Department of Pathological Biochemistry, Medical Research Institute, Tokyo Medical and Dental University, Tokyo 101-0062, Japan.
Genes Cells. 2004 Dec;9(12):1297-308. doi: 10.1111/j.1365-2443.2004.00809.x.
Hepatic differentiation from mouse embryonic stem (ES) cells via the formation of embryoid bodies (EBs) has been revealed by the expression of hepatocyte-related genes such as alpha-fetoprotein and albumin. It is known, however, that the visceral endoderm differentiates in early EBs and expresses these hepatocyte-related genes. Thus, it remains unclear whether ES cells are capable of differentiating into hepatocytes derived from definitive endoderm in vitro. In the present study, yolk sac tissues isolated from the foetal mouse were found to express many hepatocyte-related genes. Among the hepatocyte-related genes examined, cytochrome P450 7A1 (Cyp7a1) was identified as a liver-specific gene that was not expressed in the yolk sac. Cyp7a1 was induced in developing EBs, and hepatic differentiation was preferentially observed in the developing EBs in attached culture as compared to those in suspension culture. Leukaemia inhibitory factor permitted the differentiation of visceral endoderm, but inhibited the expression of gastrulation-related genes and the hepatic differentiation in cultured EBs. ES cells expressing green fluorescent protein (GFP) under the control of the Cyp7a1 enhancer/promoter showed that cultured EBs contained GFP-positive epithelial-like cells. These results demonstrate that ES cells can differentiate in vitro into hepatocytes derived from definitive endoderm.
通过胚胎体（EBs）的形成从小鼠胚胎干细胞（ES）分化出肝脏细胞，这已通过甲胎蛋白和白蛋白等肝细胞相关基因的表达得以揭示。然而，已知内胚层在早期EBs中分化并表达这些肝细胞相关基因。因此，ES细胞是否能够在体外分化为源自定形内胚层的肝细胞仍不清楚。在本研究中，发现从胎鼠分离的卵黄囊组织表达许多肝细胞相关基因。在所检测的肝细胞相关基因中，细胞色素P450 7A1（Cyp7a1）被鉴定为一种在卵黄囊中不表达的肝脏特异性基因。Cyp7a1在发育中的EBs中被诱导，并且与悬浮培养的EBs相比，在贴壁培养的发育中的EBs中优先观察到肝脏分化。白血病抑制因子允许内胚层分化，但抑制原肠胚形成相关基因的表达以及培养的EBs中的肝脏分化。在Cyp7a1增强子/启动子控制下表达绿色荧光蛋白（GFP）的ES细胞表明，培养的EBs含有GFP阳性的上皮样细胞。这些结果表明，ES细胞能够在体外分化为源自定形内胚层的肝细胞。
