Effect of enoxaparin and onion extract on human skin fibroblast cell line - Therapeutic implications for the treatment of keloids

Context: Keloids and hypertrophic scars are hyperproliferative skin disorders resulting in abnormal wound healing. In the prevention and treatment of keloids and hypertrophic scars, ointments containing heparin and onion extract are very popular. Their therapeutic effects, however, are still controversial and the mechanism of action is not fully understood. Objective: The aim of this study was to assess the effect of enoxaparin and dry onion extract on proliferation, apoptosis and beta 1 integrin expression in human fibroblasts. Materials and methods: Fibroblast human cell lines (46 BR. 1 N) were treated for 48 h with various concentrations of enoxaparin sodium (20, 100, 500 mu g/mL) and/or onion [Allium cepa L. (Alliaceae)] extract (50, 250, 1000 mu g/mL). The cell proliferation was evaluated by [H-3]-thymidine incorporation assay. Furthermore, the expression of beta 1 integrin and apoptosis was determined by flow cytometry. Results and discussion: The results demonstrate that enoxaparin and onion extract inhibited the proliferation of human fibroblasts. Almost complete inhibition of cell proliferation was achieved by enoxaparin in 500 mu g/mL concentration (91.5% reduction). The onion extract at a concentration of 250 mu g/mL also strongly inhibited the proliferation of cells (50.8% reduction). Depending on concentration, enoxaparin and onion extract induced apoptosis (500 and 1000 mu g/mL, respectively) and, depending on concentration, downregulated the expression of beta 1 integrin on human fibroblasts. Conclusion: This work points at possible mechanism of action of enoxaparin and onion extract, when administered in the treatment of patients with keloids and hypertrophic scars.