Decoding cell shapes, mechanical stress and collective dynamics in human bronchial epithelial cells.

It has been broadly recognized that the mechanical force transmission can be equally important as genetics and biochemistry in regulating tissue organization in various biological processes, including morphogenesis, wound healing and disease progression. In order to make useful predictions for large scale cell remodeling in tissues, we must understand their material properties, such as the forces that build up inside them, characterized by pressures and stresses and the spatial variation of these mechanical measures. Here we use the recently developed set of mechanical inference methods to investigate the inter-cellular stresses in cultured human bronchial epithelial cells. By assuming mechanical equilibrium, we infer the tensions along cell edges and pressures within each cell from the cell configurations. This method provides a spatial distribution of stresses and directly couples mechanics to morphology. We pay significant attention to any contribution from the 'rosette' configurations (cell vertices with connectivity of four or more) which are like the topological defects in a tissue.