Gastruloid-derived Primordial Germ Cell-like Cells (Gld-PGCLCs) develop dynamically within integrated tissues
Primordial Germ Cells (PGCs) are a rare population of cells specified early in embryonic development that give rise to gametes - sperm and egg cells. Current in vitro systems to derive PGC-like cells (PGCLCs) from pluripotent cells use large embryoid bodies, exposed to signalling cocktails, that do not recapitulate the native embryonic environment during PGC formation. Here we show that mouse gastruloids, three-dimensional in vitro models of gastrulation, generate a population of Gastruloid-derived PGC-like cells (Gld-PGCLCs) that resemble early PGCs in vivo. Importantly, the conserved organisation of mouse gastruloids leads to coordinated spatial and temporal localisation of Gld-PGCLCs relative to surrounding somatic cells, even in the absence of exogenous PGC-specific signalling or extraembryonic tissues. In gastruloids, self-organised interactions between cells and tissues, including the endodermal epithelium, enables the specification, migration, and subsequent maturation of a pool of Gld-PGCLCs. As such, mouse gastruloids represent a new source of PGCLCs in vitro and, due to their inherent co-development, serve as a novel model of dynamic PGC development within integrated tissue environments. Overall design: To characterise gastruloid-derived primordial germ cell-like cells (Gld-PGCLCs) we generated mouse gastruloids and sorted populations of putative PGCLCs at 120h for single cell RNA-sequencing