Optimizing And Application Of In Vitro Models Generating PGCs From ESCs

Primordial germ cells are the first germ cell population emerging from early embryos to pass genetic information through generations.It has been difficult to explore the specification and differentiation of PGCs, mainly because of its limited numbers in vivo during early embryogenesis,the difficulty to manipulate in vitro,and the ethical restrictions. Therefore,the in vitro derivation of PGCs from ESCs is of great significance. Although much progress has been made recently,further work is guaranteed develop a simpler and more practicable in vitro model system for PGCs derivation.In this study,we optimized models that derived PGCs from hESCs and mESCs.Specifically for hESCs,a "monolayer differentiation-SSEA1 "model was established.We found that SSEA1 positive cells emerge upon the short-term induction from hESCs by monolayer differentiation and can be upregulated by ectopic expression of Dazl and BMP4,RA,ActivinA.In addition,SSEAl+cells demonstrated imprint erasure of H19-CTCF6 loci,indicating an enrichment of post-migrating PGCs.We further demonstrated that Gasz promoted PGCs derivation from hESCs using this model.Regarding to mESCs,we sought to improve the EB differentiation system using the existing reporter line BVSC(Blimpl-mVenus and Stella-ECFP).We found that the percentage of Blimp 1+Kit+ and Blimp1+ CXCR4+ cells were modulated by ectopic expressing germ cell-specific gene Dazl.Further characterization reveals that Blimp1+ Kit+ may be partially enriched for PGCs.