Epiblast inducers capture mouse Trophectoderm Stem Cells in vitro and pattern blastoids for implantation in utero. [bulk RNA-Seq]

The embryo instructs the allocation of cell states to spatially regulate growth and functions. In the blastocyst, the formation and divergence of the trophoblast lineage ensures successful implantation and placental development. Here, we defined an optimal set of molecules secreted by the inner epiblast cells (inducers) that captures stable, highly self-renewing, pre-implantation-like mouse trophectoderm stem cells (TESCs). When exposed to suboptimal inducers, these stem cells form interconvertible subpopulations with reduced self-renewal, known as trophoblast stem cells (TSCs), and resembling peri-implantation progenitors. TECSs have an enhanced capacity to form blastoids that implant more efficiently in utero. We find that this enhanced capacity is due to epiblast inducers not only controlling trophoblast growth but also trophoblast secretion of WNT6/7B that stimulates uterine decidualization. Thus, the embryo leverages epiblast inductions to drive both the growth and decidualization potential of trophoblasts required for implantation and development. Overall design: For each sample, we analyzed three thecnical replicates except for the sorted populations (in the sample description, H correspond to "high" whereas L to "low"). C3.1 cell line was cultured in TX condition and used as a non-treated control.