Chemically defined medium is widely used for culturing mouse embryonic stem cells (mESCs), in which N2B27 works as a substitution for serum, and GSK3β and MEK inhibitors (2i) help to promote ground-state pluripotency. However, recent studies suggested that MEKi might cause irreversible defects that compromise the developmental potential of mESCs. Here, we demonstrated the deficient bone morphogenetic protein (BMP) signal in the chemically defined condition is one of the main causes for the impaired pluripotency. Mechanistically, activating the BMP signal pathway by BMP4 could safeguard the chromosomal integrity and proliferation capacity of mESCs through regulating downstream targets Ube2s and Chmp4b. More importantly, BMP4 promotes a distinct in vivo developmental potential and a long-term pluripotency preservation. Besides, the pluripotent improvements driven by BMP4 are superior to those by attenuating MEK suppression. Taken together, our study shows appropriate activation of BMP signal is essential for regulating functional pluripotency and reveals that BMP4 should be applied in the serum-free culture system.
Animals ; Bone Morphogenetic Protein 4/metabolism* ; Cell Differentiation ; Chromosomal Instability ; Endosomal Sorting Complexes Required for Transport ; Mice ; Mitogen-Activated Protein Kinase Kinases/metabolism* ; Mouse Embryonic Stem Cells/cytology* ; Pluripotent Stem Cells/cytology* ; Signal Transduction ; Ubiquitin-Conjugating Enzymes

N

Self-organized blastoids from extended pluripotent stem (EPS) cells possess enormous potential for investigating postimplantation embryo development and related diseases. However, the limited ability of postimplantation development of EPS-blastoids hinders its further application. In this study, single-cell transcriptomic analysis indicated that the "trophectoderm (TE)-like structure" of EPS-blastoids was primarily composed of primitive endoderm (PrE)-related cells instead of TE-related cells. We further identified PrE-like cells in EPS cell culture that contribute to the blastoid formation with TE-like structure. Inhibition of PrE cell differentiation by inhibiting MEK signaling or knockout of Gata6 in EPS cells markedly suppressed EPS-blastoid formation. Furthermore, we demonstrated that blastocyst-like structures reconstituted by combining the EPS-derived bilineage embryo-like structure (BLES) with either tetraploid embryos or tetraploid TE cells could implant normally and develop into live fetuses. In summary, our study reveals that TE improvement is critical for constructing a functional embryo using stem cells in vitro.
Pregnancy ; Female ; Animals ; Mice ; Tetraploidy ; Blastocyst ; Embryo, Mammalian ; Cell Differentiation ; Embryonic Development