A Single Small-Molecule-Based Human Embryo Model Reveals V-ATPase Requirement in Mammalian Blastocyst Cavitation

Despite the rapid advances in human blastoid models, their potential to uncover fundamental mechanisms of early development remains limited, leaving key morphogenetic processes poorly understood. Here, we present a simple and robust system in which dimethyl sulfoxide (DMSO) alone induces blastoid formation from human nPSCs.

This model faithfully recapitulates pre- and post-implantation features, including amniotic cavity formation, and reveals a previously unrecognized mechanism of trophectoderm (TE) cavitation. Using this system, we identified lysosome-related genes—particularly those encoding subunits of the proton pump V-ATPase—are essential for blastoid cavitation. DMSO treatment upregulates key V-ATPase subunits (ATP6V0A4 and ATP6V1B1), which are also enriched in the TE of human embryos.