Embryonic stem cells derived from developmentally incompetent embryos deficient in maternal and zygotic Cdx2

Separation of cell lineages during early mammalian development is required to establish the pluripotent founder cell population that will give rise to the embryo proper and a functional trophoblast to support its development. We systemically assessed the role of the homeobox gene Cdx2 in vivo and in vitro development with an RNAi approach. Effective elimination of both maternal and zygotic Cdx2 resulted in typical phenotypes of Cdx2-mutant embryos, such as failure of hatching and implantation. However, the blastulation and expression of TE specific markers in these Cdx2-deficient embryos excluded the possibility of Cdx2 to act as a TE determinant, although compromised structure and functioning of TE was observed and the resulted embryos were not viable. Strikingly, the efficiency of stem cell derivation was significantly higher than control when embryos were put on MEF at the 8-cell stage and the derived stem cells were fully pluripotent as shown by chimera and tetraploid complementation experiments. Comparative genomic hybridization of wild type and Cdx2 mutant at 8-cell and blastocyst mouse embryos were performed. 8-cell biological duplicates and blastocyst stage biological triplicates embryos were used.The hybridization experiments were duplicated in a reciprocal labeling manner to reduce dye integration bias (dye-swaps).