Defined conditions control the morphological dualism of rat primitive extraembryonic endoderm stem cells

We report two chemically defined conditions that differ by the addition of the cytokine Lif and the β-catenin-stabilizing drug Chir99021 and enable permanent self-renewal as mesenchymal and epithelial morphotypes, respectively. The morphotypes are interconvertible and differentiate equipotently. Surprisingly, the proliferation of both morphotypes requires Lif/Gp130/Stat3 signaling (autocrine in the absence of added Lif) and non-canonical Wnt signaling (autocrine). Additionally, the epithelial version requires β-catenin for proliferation and morphology. Interestingly, the mesenchymal cells also express key epithelial markers, but those are improperly structured and/or not functional, indicating a primed state. The results provide an improved platform for studying the proliferation and plasticity of the early extraembryonic endoderm, which occurs in mesenchymal and epithelial forms in vivo.本研究报道了两种化学成分明确的培养条件，二者的差异在于分别添加了细胞因子Lif（Leukemia Inhibitory Factor）与β-连环蛋白（β-catenin）稳定药物Chir99021，可分别支持间充质形态型与上皮形态型细胞实现永久自我更新。上述两种形态型可相互转化，且具备等同的分化潜能。令人意外的是，两种形态型细胞的增殖均依赖Lif/Gp130/Stat3信号通路（未添加外源性Lif时为自分泌激活）与非经典Wnt信号通路（自分泌激活）。此外，上皮形态型细胞的增殖与形态维持均依赖β-连环蛋白（β-catenin）。值得关注的是，间充质形态型细胞亦可表达关键上皮标志物，但这些标志物结构异常且/或功能缺失，提示其处于预激活状态。本研究结果为探究早期胚外内胚层的增殖与可塑性提供了更优化的研究平台——该类细胞在体内以间充质与上皮两种形态存在。