Active cop, passive cop: developmental stage-specific modes of wound-induced blood cell recruitment in Drosophila

In the past few years a number of fly labs have studied wounded Drosophila embryos,(1-3) larvae(4-6) and adults7 in an effort to uncover the molecular/genetic basis of wound healing responses. The early studies in this growing field focused on the signature event of wound healing--the closure of the epidermal gap through cell migration. These studies showed that there is a conserved dichotomy between embryonic and postembryonic repair processes in flies and vertebrates: embryonic wounds heal through contraction of a supracellular actin pursestring assembled at the wound margin and postembryonic wounds heal through extension of cell processes and migration across the wound gap. Now, our group and others have begun to use these wounding assays to examine other steps of the healing process. Inflammation, the recruitment of hemocytes (blood cells) to the site of tissue damage, has been a particular focus of recent studies. This extra view article summarizes these recent findings on wound-induced inflammation, especially the curious dichotomy between modes of blood cell recruitment in embryos and larvae.