Linear viscoelastic properties of the vertex model for epithelial tissues

Epithelial tissues act as barriers and, therefore, must repair themselves, respond to environmental changes and grow without compromising their integrity. Consequently, they exhibit complex viscoelastic rheological behavior where constituent cells actively tune their mechanical properties to change the overall response of the tissue, e.g., from solid- to fluid-like. Mesoscopic mechanical properties of epithelia are commonly modeled with the vertex model~(VM). While previous studies have predominantly focused on the longtime behavior, we systematically studied rheological properties of the VM in the full dynamic range by applying small oscillatory shear and bulk deformations both in solid- and fluid-like phases. We found that the shear and bulk responses in the fluid and solid phases can be described by standard spring-dashpot viscoelastic models. Furthermore, the solid-fluid transition can be tuned by applying pre-deformation to the system. Our study provides insights into the mechanisms by which epithelia can regulate their rich rheological behavior.