Wound-Induced Syncytia Outpace Mononucleate Neighbors duringDrosophilaWound Repair

All organisms have evolved to respond to injury. Cell behaviors like proliferation, migration, and invasion replace missing cells and close wounds. However, the role of other wound-induced cell behaviors is not understood, including the formation of syncytia (multinucleated cells). Wound-induced epithelial syncytia were first reported around puncture wounds in post-mitoticDrosophilaepidermal tissues, but have more recently been reported in mitotically competent tissues such as theDrosophilapupal epidermis and zebrafish epicardium. The presence of wound-induced syncytia in mitotically active tissues suggests that syncytia offer adaptive benefits, but it is unknown what those benefits are. Here, we usein vivolive imaging to analyze wound-induced syncytia in mitotically competentDrosophilapupae. We find that almost half the epithelial cells near a wound fuse to form large syncytia. These syncytia use several routes to speed wound repair: they outpace diploid cells to complete wound closure; they reduce cell intercalation during wound closure; and they pool the resources of their component cells to concentrate them toward the wound. In addition to wound healing, these properties of syncytia are likely to contribute to their roles in development and pathology.