Construction of a Mammalian Embryo from Embryonic Stem Cells Instructed by Morphogen Gradients

Generating properly organized and differentiated embryonic structures in vitro from aggregates of pluripotent cells remains a major challenge. In a living embryo, the interplay in between signaling molecules known as morphogens and their antagonists lead to 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 the function of an embryo organizer and to trigger embryonic development. The resulting embryoids are remarkably well patterned along anterior-posterior and dorsal-ventral axes, generate three germ layers through a process of gastrulation and differentiate germ layer derivatives (including notochord, vasculature, neural tube, neural crest, endoderm) similar to an authentic embryo at E9-E9.5. Overall design: Trancriptome of pools of 12 Embryoids were compared to the ones of pool of 12 controls (aggregates of embryonic stem cells not instructed by a morphogen signaling center) 7 days (D7) or 8 days (D8) after aggregation of stem cells (from the E14TG2a line) in hanging drops. Triplicates were analyzed for each experimental condition.