Profiling the transient gastrulation inducing property of amnion-like cells.

In the primate embryo, the amnion rather than the trophectoderm is directly juxtaposed to the epiblast and may play this role. To model the interactions between the amnion and epiblast, we differentiated human pluripotent stem cells (hPSCs) to amnion-like cells (AMLCs) and juxtaposed them in a controlled manner with undifferentiated hPSCs, which represent the epiblast.

We found that juxtaposition between these cell types is sufficient to initiate a range of cell behaviors associated with gastrulation including organized differentiation to primitive streak and downstream mesendodermal cell fates and directed cell migration out of the primitive streak region. Performing knockout experiments specifically in either the epiblast or amnion compartment revealed intricate crosstalk that is required to properly initiate gastrulation.