Trophectoderm-like cells from EPS cells enable generating EPS cell-derived post-implantation embryoids that complete gastrulation [scRNA-seq]

Mouse extended pluripotent stem (EPS) cells have demonstrated significant potential for generating embryo models in vitro. However, their limited capacity for extraembryonic trophoblast development has hindered their use in constructing whole embryo models, particularly post-implantation embryoids. Here, we establish a stepwise induction protocol to generate trophectoderm-like cells from mouse EPS cells. These cells retain trophectoderm-specific transcriptomic features and can differentiate into trophoblast lineages in vivo. Moreover, combining these trophectoderm-like cells with EPS cell-derived primitive endoderm/epiblast bilineage structures enabled the robust generation of post-implantation embryoids in a transgene-free manner. EPS-derived embryoids recapitulate key developmental events of post-implantation mouse embryos, including the formation of the pro-amniotic cavity, anterior-posterior axis, primitive streak, gastrulation, and complex extraembryonic tissues. Notably, single-cell transcriptomic analysis revealed a high degree of transcriptional similarity between EPS-derived embryoids at day 6 and natural E7.5 mouse embryos. Our study presents a novel platform for modeling post-implantation mouse embryogenesis in vitro. Overall design: A total of 2 scRNAseq samples of day 6 EPS-derived embryoids were analyzed, similar to E7.5 stage in vivo

小鼠扩展多能干细胞（extended pluripotent stem cells，EPS）在体外构建胚胎模型领域已展现出显著应用潜力。然而其胚外滋养层发育能力有限，这一缺陷阻碍了其用于构建完整胚胎模型，尤其是植入后胚胎类器官。本研究建立了一套分步诱导方案，可从小鼠EPS细胞中诱导产生滋养层样细胞。此类细胞保留滋养层特异性转录组特征，并可在体内分化为滋养层谱系。此外，将该滋养层样细胞与EPS细胞来源的原始内胚层/上胚层双谱系结构相结合，可实现无转基因方式高效构建植入后胚胎类器官。EPS细胞来源的胚胎类器官可重现小鼠植入后胚胎的关键发育事件，包括前羊膜腔形成、前后轴、原条、原肠运动以及复杂胚外组织的发育。值得注意的是，单细胞转录组分析显示，培养第6天的EPS来源胚胎类器官与体内E7.5期小鼠胚胎具有高度相似的转录谱。本研究为体外模拟小鼠植入后胚胎发生提供了全新的研究平台。整体实验设计：本研究共分析了2份培养第6天EPS来源胚胎类器官的单细胞RNA测序（single-cell RNA sequencing，scRNAseq）样本，其发育阶段对应体内E7.5期胚胎。