Implantation-Competent Blastocyst-Like Structures from Mouse Pluripotent Stem Cells

Soon after fertilization, the few totipotent cells of mammalian embryos diverge to form a structure called the blastocyst (BC). Although numerous types of cells, including germ cells and extended pluripotency stem cells, have been generated from pluripotent stem cells (PSCs) in-vitro, generating functional BCs only from PSCs has not yet been reported. Here we describe induced self-organizing 3D BC-like structures (iBCs) generated from mouse PSC culture in-vitro. Resembling natural BCs, iBCs have a blastocoel-like cavity and were formed with outer cells that are positive for trophectoderm lineage markers and with inner cells that are positive for pluripotency markers. iBCs transplanted to pseudopregnant mice uteruses implanted, induced decidualization, and exhibited growth and development before resorption, demonstrating that iBCs are implantation-competent. iBC production required the transcription factor Prdm14 and iBC precursor intermediates concomitantly activate the MERVL totipotency related cleavage stage reporter. Thus, our system may contribute to understanding molecular mechanisms underpinning totipotency, embryogenesis, and implantation.