Nakanishi Mio, Kurisaki Akira, Hayashi Yohei, Warashina Masaki, Ishiura Shoichi, Kusuda-Furue Miho, Asashima Makoto
Department of Life Sciences (Biology), Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1, Komaba, Meguro-ku, Tokyo, 153-8902, Japan.
FASEB J. 2009 Jan;23(1):114-22. doi: 10.1096/fj.08-111203. Epub 2008 Sep 22.
Formation of the primitive streak (PS) is the initial specification step that generates all the mesodermal and endodermal tissue lineages during early differentiation. Thus, a therapeutically compatible and efficient method for differentiation of the PS is crucial for regenerative medicine. In this study, we developed chemically defined serum-free culture conditions for the differentiation of embryonic stem (ES) cells into the PS-like cells. Cultures supplemented with Wnt showed induction of expression of a PS marker, the brachyury gene, followed by induction of the anterior PS markers goosecoid and foxa2, a posterior PS marker, evx1, and the endoderm marker sox17. Similar differentiation of PS by Wnt was also observed in human ES cells. Moreover, we revealed that the activation of the Wnt canonical pathway is essential for PS differentiation in mouse ES cells. These results demonstrated that Wnt is an essential and sufficient factor for the induction of the PS-like cells in vitro. These conditions of induction could constitute the initial step in generating therapeutically useful cells of the definitive endoderm lineage, such as hepatocytes and pancreatic endocrine cells, under chemically defined conditions.
原条（PS）的形成是早期分化过程中产生所有中胚层和内胚层组织谱系的初始特化步骤。因此，一种治疗上兼容且有效的原条分化方法对于再生医学至关重要。在本研究中，我们开发了化学成分明确的无血清培养条件，用于将胚胎干细胞（ES细胞）分化为类原条细胞。添加Wnt的培养物显示出原条标志物短尾基因表达的诱导，随后诱导前部原条标志物鹅膏蕈氨酸和叉头框A2、后部原条标志物Evx1以及内胚层标志物Sox17。在人ES细胞中也观察到Wnt对原条的类似分化作用。此外，我们发现Wnt经典信号通路的激活对于小鼠ES细胞的原条分化至关重要。这些结果表明，Wnt是体外诱导类原条细胞的必要且充分因素。这些诱导条件可能构成在化学成分明确的条件下生成治疗上有用的定形内胚层谱系细胞（如肝细胞和胰腺内分泌细胞）的初始步骤。
