Topical bilirubin-deferoxamine hastens excisional wound healing by modulating inflammation, oxidative stress, angiogenesis, and collagen deposition in diabetic rats

The study was performed to understand the detailed mechanism of diabetic wound healing by bilirubin-deferoxamine (DFO) combination on topical application. There were two study groups, control, and treatment. The granulation tissues collected on different days (3, 7, 14, and 19) were studied in detail for inflammatory mediators, angiogenesis markers, epithelialization, and oxidative stress parameters. A significant increase in wound contraction percentage was observed from day 7 in the bilirubin-DFO treatment group. The combinatorial treatment significantly reduced tumour necrosis factor-alpha (TNF-α) and interleukin-1 beta (IL-1β), and enhanced IL-10 levels. Upregulated mRNAs of vascular endothelial growth factor (VEGF) and hypoxia-inducible factor-1 alpha (HIF-1 α) along with CD31 immunohistochemistry showed the pro-angiogenesis potential of the combination. Hematoxylin and Eosin (H and E) staining and Masson's trichrome staining showed reduced inflammatory cell infiltration, enhanced fibroblast proliferation, well-organized collagen fibers, and the development of new blood vessels. Collagen deposition is further supported by immunohistochemistry studies and Masson's trichrome staining. Bilirubin-DFO combination also reduced lipid peroxidation and elevated antioxidative enzymes. Topical application of bilirubin-DFO showed immense potential in augmenting skin wound regeneration in diabetes by upregulating the antioxidant status as well as increasing angiogenesis, collagen deposition, and modulating cytokines. •Simultaneous bilirubin and DFO treatment caused rapid and well-organized healing of cutaneous wounds in diabetic rats.•It showed the up-regulation of anti-inflammatory and angiogenic mediators, and downregulation of inflammatory mediators.•Marked collagen deposition along with reduction of oxidative stress, and better epithelialization was also observed.