Effect of botulinum toxin type A in the contraction of lesions treated with full-thickness grafts

Background The treatment of traumatic injuries and burns presenting tissue loss—which are called full-thickness wounds—is primarily accomplished with skin grafts. This, however, remains an ongoing challenge because grafts have a number of limitations, perhaps being the secondary contraction determining movement restriction due to graft contracture, the main one. In this context, the currently available treatments are—in many cases—insufficient, and thus, the search for new alternatives is necessary. The objective was to evaluate the effect of botulinum toxin type A (in different doses) in the contraction of full-thickness wounds treated with full-thickness grafts. Methods Eighteen male Wistar rats were used, with an average weight of 350 g, divided into three groups. In group 1, two full-thickness wounds were produced on their back. The first wound was subjected to graft + 1 Ui/cm 2 and the second one was subjected only to skin graft. The same routine was done in group 2, except with a dose of 2 Ui/cm 2 . In group 3, aiming at a 14-day histological analysis, three full-thickness wounds were produced. On the first wound, a graft + toxin 1 Ui/cm 2 was used, on the second one, a graft + toxin 2 Ui/cm 2 , and on the third, only the graft was done. The areas of injury were analyzed by both digital photography—at 7, 14, and 28 days—and histology—at 14 and 28 days. Results Decreased contractions of the graft (at 28 days) in the lesions treated with toxin 1 Ui/cm 2 ( p < 0.05) and 2 Ui/cm 2 ( p < 0.01) were observed. The epithelialization and neovascularization were not altered by the toxin, either at 14 or 28 days ( p > 0.05). The degree of inflammation was reduced after 14 days in toxin-treated groups ( p < 0.05), equaling up to controls after 28 days. The density of fibroblasts ( p < 0.05) and collagen ( p < 0.05) was reduced after 28 days in both treated groups. Conclusions According to the data obtained, botulinum toxin seems to reduce secondary contraction of the graft, thus reducing local inflammation, as well as the density of fibroblasts and collagen deposition. Level of Evidence: Not ratable.