Curvature Dependent constraints drive remodeling of epithelia

Epithelial tissues are essential to keep a proper barrier for the organism. They usually have highly curved shapes, such as tubules or cysts. However, interplays between the environment and cell mechanical properties to set the shape are not known. In this study, we encapsulated two epithelial cell lineages, MDCK and J3B1A, into hollow alginate tubes and grew them under cylindrical confinement. Once formed, the epithelial MDCK layer detached from the alginate shell, while J3B1A layer remained adherent. Detachment resulted from contractile forces within cell layers that pulled cells away from the shell. We concluded that J3B1A cells have lower contractility than MDCK cells. As the pulling forces depend on the radius of the tube, we induced detachment of J3B1A cells by reducing the size of the hollow tube by two. Moreover, in bent tubes, detachment was more pronounced on the outer side of the turn, while extrusion occurred in the inner side, further highlighting the coupling between curvature and cell contractility.