Single-cell RNA-sequencing of mouse embryoids at Day 8

Generating properly organized and differentiated embryonic structures in vitro from aggregates of pluripotent cells remains a major challenge to overcome. In the living embryo, the interplay between morphogens and their antagonists set up gradients of activity that instruct cells about their fate, leading to patterning and morphogenesis. Here we show that experimentally engineering a morphogen signaling center within an aggregate of mouse pluripotent stem cells is sufficient to mimic in vitro the function of an embryo organizer and to trigger embryonic development. The resulting embryoids are extensively patterned along their anterior-posterior and dorsal-ventral axes, with formation of three germ layers through a process of gastrulation and differentiation of germ layer derivatives similar to those of a neurula-stage mouse embryo. Dissociated cells from a pool of 90 embryoids at Day 8 of development fixed in methanol.

从多能细胞聚集体体外构建结构规整且分化成熟的胚胎结构，仍是亟待突破的重大科研难题。在活体胚胎中，形态发生素（morphogen）与其拮抗剂之间的相互作用会构建活性梯度，指导细胞的命运决定，进而调控胚胎的模式形成与形态发生过程。本研究证实，在小鼠多能干细胞聚集体中实验性构建形态发生素信号中心，即可在体外模拟胚胎组织者的功能，并启动胚胎发育进程。所获得的类胚胎体（embryoid）可沿前后轴与背腹轴实现广泛的模式构建，并通过原肠胚形成过程生成三胚层，其胚层衍生物的分化特征与神经胚阶段的小鼠胚胎高度相似。本研究的样本为从90个发育至第8天、经甲醇固定的类胚胎体中解离获取的细胞。