  Cell monolayers provide an interesting example of active matter, exhibiting a
phase transition from a flowing to jammed state as they age. Here we report
experiments and numerical simulations illustrating how a jammed cellular layer
rapidly reverts to a flowing state after a wound. Quantitative comparison
between experiments and simulations shows that cells change their
self-propulsion and alignement strength so that the system crosses a phase
transition line, which we characterize by finite-size scaling in an active
particle model. This wound-induced unjamming transition is found to occur
generically in epithelial, endothelial and cancer cells.
