Collective movements of epithelial cells during resealing and migration:

We used two different types of assays to probe the dynamics of epithelial cells under mechanical and geometrical constraints. Fundamental biological processes such as morphogenesis and wound healing involve the closure of epithelial gaps. Epithelial gap closure is commonly attributed either to the purse-string contraction of an intercellular actomyosin cable or to active cell migration, but the relative contribution of these two mechanisms remains unknown. Here we present a model experiment to systematically study epithelial closure in the absence of cell injury. Our results reveal that the closure of epithelial gaps in the absence of cell injury is governed by the collective migration of cells through the activation of lamellipodium protrusion (collaborations with X. Trepat IBEC, Spain and Mechanobiology Institute, Singapore). Then we studied the role of geometrical confinement on collective cell migration. We show that the geometrical properties of the environment regulate the formation of collective cell migration patterns through cell–cell interactions. Using microfabrication techniques to allow epithelial cell sheets to migrate into strips whose width was varied from one up to several cell diameters, we identified the modes of collective migration in response to geometrical constraints (coll. CT Lim, National University of Singapore).