Facilitating action of asiaticoside at low doses on burn wound repair and its mechanism

Some reports published from 1967 to 1999 describe the use of ointments containing high doses (0.1 to 0.2%, w/w) C. asiataica herb extracts to enhance wound repair. Lower doses at which burn wound repair is enhanced by such topical applications have not been established yet. We found that the application of asiaticoside at low doses of 10(-8) to 10(-12)% (w/w) facilitated burn wound repair. To clarify the accelerating mechanisms of asiaticoside on burn wound repair, we examined the effects of asiaticoside on the levels of various cytokines produced at the site of the burn wound. The topical application of a low dose (10 pg, 1 ng, or 100 ng/wound area) of asiaticoside increased monocyte chemoattractant protein-1 (MCP-1), vascular endothelial growth factor (VEGF), and interleukin (IL)-1beta levels in burn wound exudates. Asiaticoside (10 pg to 100 ng/ml) enhanced MCP-1 production in HaCaT cells, but it had no direct effect on VEGF production. Furthermore, asiaticoside (10 pg to 100 ng/ml) increased the IL-1beta production in THP-1 macrophages with MCP-1, but it had no effect on IL-1beta production without MCP-1 or with lipopolysaccharide (LPS). These findings suggest that the enhancement of burn wound healing by asiaticoside might be due to the promotion of angiogenesis during skin wound repair as a result of the stimulation of VEGF production caused by the increase in MCP-1 expression in keratinocytes and the increase in IL-1beta expression in macrophages induced cooperatively by asiaticoside plus MCP-1.