Specification of human germ cell fate with enhanced progression capability

Human primordial germ cells (hPGCs) are the embryonic precursors of sperm and eggs. While the exact temporal window of hPGC specification and the cellular identity of their precursors remains unclear, few studies on ex vivo and in vitro cultured human embryos reported plausible hPGCs on embryonic day (E) 12−13, and in a E16−17 gastrulating embryo. In vitro, hPGC-like cells (hPGCLCs) can be specified from intermediary pluripotent stage or peri-gastrulation precursors. Nevertheless, it remains unclear the extent of the spectrum of precursors for hPGCLC specification and how these different cellular identities impact hPGCLC development. Here we show that capacitating and resetting precursors respond to BMP and induce resetting hPGCLCs (rhPGCLCs). Strikingly, rhPGCLC in the human hindgut organoid co-cultures show progression at a pace reminiscent of in vivo timing, demonstrating their higher potential for progression compared to those derived from peri-gastrulation precursors. Notably, EOMES and TBXT act synergistically during rhPGCLC specification, while only EOMES is necessary for peri-gastrulation hPGCLC specification. Our results emphasize the notion that the function of a cell identity can be largely influenced by features of their precursors rather than their convergent identity. Importantly, our study provides the foundation for refined and efficient in vitro models of human gametogenesis, which may contribute to design new therapeutic approaches for human infertility. RNA-seq of hESC-derived cell types (2-4 biological replicates for each cell type)