Geometric Confinement-Mediated Mechanical Tension Directs Patterned Differentiation of Mouse ESCs into Organized Germ Layers

The self-organization of embryonic stem cells (ESCs)into organizedtissues with three distinct germ layers is critical to morphogenesisand early development. While the regulation of this self-organizationby soluble signals is well established, the involvement of mechanicalforce gradients in this process remains unclear due to the lack ofa suitable platform to study this process. In this study, we developeda 3D microenvironment to examine the influence of mechanical tensiongradients on ESC-patterned differentiation during morphogenesis bycontrolling the geometrical signals (shape and size) of ESC colonies.We found that changes in colony geometry impacted the germ layer pattern,with Cdx2-positive cells being more abundant at edges and in areaswith high curvatures. The differentiation patterns were determinedby geometry-mediated cell tension gradients, with an extraembryonicmesoderm-like layer forming in high-tension regions and ectodermal-likelineages at low-tension regions in the center. Suppression of cytoskeletaltension hindered ESC self-organization. These results indicate thatgeometric confinement-mediated mechanical tension plays a crucialrole in linking multicellular organization to cell differentiationand impacting tissue patterning.