Extracellular and intercellular force distribution in circularly shaped epithelia

Abstract Stress homeostasis in multicellular organisms is essential to their growth, development, and repair. However, how cellular forces are generated and transmitted within a multicellular organism to maintain stress homeostasis remains poorly understood. Here we employ cellular force microscopies to quantify extracellular traction and intercellular tension of circularly shaped cohesive epithelia seeded on hydrogels of various stiffness. A minimal model is developed and predicts exponential decay of extracellular traction from the periphery to the center of the epithelial monolayers, which agrees with the experimental data. By matching the experimental and modeling results on the extracellular traction profiles, we further show that intracellular contraction increases monotonically with the hydrogel stiffness, and then reaches a plateau, manifesting the cross-talk between the cell monolayer and the extracellular matrix. Our study sheds light on the partition of intracellular contraction into intercellular tension and extracellular traction and lays down a foundation for future modeling and experimental measurements of cellular force generation and transmission.