Role of the supracellular actomyosin cable during epithelial wound healing.

The closure of wounds in epithelia is center to many physiological processes in both development and repair of multicellular organisms. Depending on the biochemical and mechanical environment as well as cell type, this collective cellular movement often involves coordinated cell crawling and the purse-string contraction of a supracellular actomyosin ring around the wound. However, it remains uncertain how these two mechanisms cooperatively contribute to the wound healing, and especially the role of the ring is not clear. To decipher this complex process, we develop a particle-based model that includes purse-string contraction, cell crawling and other properties incorporated with monolayers of Madin-Darby canine kidney (MDCK) cells. Our model captures the traction force patterns under several different conditions in experiments. In addition to traction force pointing away from the wound on the leading edge, we observed patterns of traction force pointing towards the wound. We show this inward pointing force pattern is induced by the purse-string contraction. Our model also explains the effects of the purse-string ring and which parameters affect the relative efficiency of these two mechanisms.