SRA

In vitro gametogenesis, the process of generating gametes from pluripotent cells in culture, is a powerful tool for improving our understanding of germ cell development as well as an alternative source of gametes.(1) Conservation of the northern white rhinoceros (NWR), a species for which only two females remain, would be a compelling application of in vitro gametogenesis as a gametes source. Here, we established a culture system that induces a robust number of primordial germ cell-like cells (PGCLCs) from pluripotent stem cells of the NWR and southern white rhinoceros (SWR), the closest species to the NWR. PGCLC differentiation from SWR embryonic stem cells is highly reliant on BMP and WNT signals, as observed in mice and humans, though the timing and duration of these signals need to be optimized for each species. Genetic analysis revealed that SOX17 is essential for SWR-PGCLC induction, as it is in humans. Under the defined condition, NWR induced pluripotent stem cells differentiated into PGCLCs whose transcriptome was highly similar to that of SWR-PGCLCs. We also identified cell surface markers, CD9 and ITGA6, that enabled us to isolate PGCLCs without genetic alteration in pluripotent stem cells. This study provides a first step toward production of NWR gametes in culture and understanding of the basic mechanism of PGC specification in a large animal. Overall design: Transcriptomes of embryonic stem cells, pre-induced cells, and primordial germ cell like cells of southern white rhinoceros and induced pluripotent stem cells, pre-induced cells, and primordial germ cell like cells of northern white rhinoceros.