Comparison of botulinum toxin type A and aprotinin monotherapy with combination therapy in healing of burn wounds in an animal model

Burns are one of the most common injuries that are complicated by many challenges including infection, severe inflammatory response, excessive expression of proteases, and scar formation. The aim of this study was to investigate the effect of botulinum toxin type A (BO) and aprotinin (AP) separately or in combination (BO-AP) in healing process. Four burn wounds were created in each rat and randomly filled with silver sulfadiazine (SSD), BO, AP and BO-AP. The rats were euthanized after 7, 14, and 28 days, and their harvested wound samples were evaluated by gross pathology, histopathology, gene expression, biochemical testing, and scanning electron microscopy. Both BO and AP significantly reduced expression of interleukin-1 beta (IL-1 beta) and transforming growth factor-beta 1 (TGF-beta 1) at the 7th post wounding day. Moreover, they inhibited scar formation by reducing the TGF-beta 1 level and increasing basic fibroblast growth factor (bFGF) at the 28th day. AP by decreasing protease production showed more effective role than BO in wound regeneration. AP increased tissue organization and maturation and improved cosmetic appearance of wounds, at 28 days. The best results gained when combination of BO and AP were used in healing of burn wounds. Treatment by BO-AP significantly subsided inflammation compared to the BO, AP, and SSD treated wounds. Treatment with BO-AP also reduced collagen density and led to minimal scar formation. Combination of botulinum toxin type A and aprotinin considerably increased structural and functional properties of the healing wounds by reducing scar formation and decreasing production of proteases.