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 ß-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 ß-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. Overall design: mRNA profiles of rat pXEN cells routinely cultured in T,LPE and CPE conditions were generated by deep sequencing, in triplicate, on an Illumina HiSeq 2500