Pretreatment of diabetic rats with lipoic acid improves healing of subsequently-induced abrasion wounds

The etiology of delayed or impaired wound-healing in diabetic individuals is multifactoral, but peripheral vascular dysfunction is an underlying factor in the majority of cases. Recent studies have shown that lipoic acid improves vascular function in diabetic skin and reduces the symptoms associated with the diabetic peripheral neuropathy. In this study, rats were made diabetic with streptozotocin (STZ) and treated systemically on alternative days with lipoic acid (100 mg/kg given via intraperitoneal injection) for 8 weeks. Untreated STZ-diabetic rats and non-diabetic rats served as control. At the end of the 8-week period, rats from all the three groups were subjected to abrasion wound formation. Skin wounds healed more rapidly in untreated non-diabetic rats than in the untreated diabetic rats. Wounds in lipoic acid-treated diabetic rats healed more rapidly than wounds in untreated diabetic rats. Subsequent in vitro studies demonstrated that lipoic acid protected endothelial cells from oxidant injury. At the same time, lipoic acid had no apparent effect on endothelial cell proliferation and had no measurable effect on fibroblast function (proliferation, collagen synthesis and matrix metalloproteinase expression). These findings suggest that prophylactic use of lipoic acid might be useful in preventing the development of non-healing skin ulcers from minor traumas in at-risk skin.