Mechanoresponse of epithelial monolayers to in-plane and out-of plane curvatures imposed by 3D microwells

The organization of epithelial tissues with precise spatial definition is essential to various biological processes and to generate curved epithelial structures, such as lobules in breast, lung and kidney tissues. However, the regulation of the architecture and dynamics of collective epithelial assemblies by the matrix curvature remains unclear. To address this challenge, we designed a new photopolymerization method through an optical photomask to create microwells of various diameters in hydrogels that mimick the native organization of epithelial monolayers in soft lobular structures. Using these well-defined microwells of different aspect ratios, we decoupled how in-plane and out-of plane curvatures modulate the mechanoresponse of epithelial tissues. Our findings show that in-plane curvature leads to the formation of an actomyosin supracellular structure formed at the edge of the microwell, while convex out-of plane curvature imposed at the microwell entrance leads to a vertical orientation of the nuclei towards the microwell axis. We demonstrated that increasing the out-of plane curvature leads to more flatten and elongated nuclear morphologies with high levels of chromatin compaction. Interestingly, our results show that epithelial cells exhibit higher directionality and speed around the microwell edge, demonstrating that the out-of-plane curvature significantly enhances the cellular trafficking, referred as curvotaxis. These findings demonstrate the importance of in-plane and out-of plane curvatures in epithelial organization and how both can be leveraged to facilitate the engineering of curved structures to study curvature-dependent mechanotransduction pathways.