Skin lesions and ulcerations are common and severe complications of diabetes. A significant proportion of these wounds fail to respond to conventional treatment, hence amputation is a feared outcome of diabetes. Overexpression of Flightless (Flii) inhibits wound healing and ablation of Flii using specific neutralising monoclonal antibodies (FnAb) enhances cellular proliferation and migration. It was therefore hypothesized that decreasing Flii expression in diabetic wounds would create a permissive environment for cellular proliferation, enhanced neovascularization, and improved healing outcomes. The aim of this study was to determine whether genetic Flii gene knockdown or treatment with FnAb were effective in improving diabetic wound repair. A mouse model of diabetes was used in which type 1 diabetes was induced using streptozotocin. Diabetes was subsequently induced in low (Flii⁺ʹ⁻), normal (WT) and high (FliiTg/Tg) [Tg/Tg in superscript] mice. Full-thickness dorsal wounds were created and it was found that these wounds healed more rapidly when Flii gene expression was decreased. Further studies revealed that this improved healing was accompanied by a robust pro-angiogenic response with significantly elevated von Willebrand factor and VEGF positive endothelial cell infiltration. In a separate study, wounds in WT diabetic mice were injected intradermally with FnAb and here too improved healing was observed with significantly increased rate of re-epithelialisation compared with placebo control. We investigated the angiogenic response of FnAb both in vitro and in vivo. FnAb enhanced capillary tube formation in human umbilical vein endothelial cells (HUVEC) and promoted formation of functional neovasculature in vivo. Mice with reduced Flii also showed increased numbers of mature blood vessels using an in vivo Matrigel plug assay with increased recruitment of α-SMA positive cells and improved tight junction aiding cell to cell attachments. In conclusion, reducing Flii levels in wounds either genetically or using neutralising antibodies promotes wound healing in diabetic mice by enhancing epithelialisation and improving angiogenic processes. Manipulating Flightless I may therefore be a potential approach for therapeutic intervention in the treatment of the diabetic foot.Thesis (Ph.D.) -- University of Adelaide, School of Paediatrics and Reproductive Health, 201
