Protocol for capturing trophectoderm stem cells reflecting the blastocyst stage

Classically, culturing mouse blastocysts with FGF4/TGF-β1, two epiblast-secreted inducers, allows for deriving trophoblast stem cells that comprise fluctuating subpopulations reflecting both pre- and post-implantation stages. However, a more complete combination of inducers (adding LPA, IL11, BMP7, Activin A, 8-Br-cAMP) captures trophectoderm stem cells with enhanced transcriptomic similarity to the blastocyst trophectoderm and self-renewal, reduced differentiation. Also, the complete combination of inducers increased potential to form blastoids and to instruct decidualization in utero, thus better reflecting the blastocyst. For complete details on the use and execution of this protocol, please refer to Seong et al.¹.