Epithelial tissues protect your body by clearly defining the boundary between you and “not you.” As such, cells within these tissues must coordinate with their neighbors to move collectively and avoid forming defects within the epithelium. When a hole, such as a wound, does form, the epithelial tissue coordinates to close the wound. We study wound healing to find fundamental rules that set the mechanical outputs of simple tissues.
One key result: Cells closest to the wound site in an epithelial tissue utilize two separate mechanisms for moving into the void and closing the wound. Mechanism #1 is a single-cell motion that utilizes a lamellipodium and is fast but “weak.” Mechanism #2 is a collective mechanism where cells “grab” their neighbors and pull as a group. This is slow but “strong.” We found that regardless of the overall mechanism utilized by cells as they close a wound, the average rate of mechanical work outputted is the same, suggesting a physical rule for the mechanical outputs of cells.