Effect of asiaticoside on hypertrophic scar in the rabbit ear model.

Background:  Previous observations suggested that asiaticoside had a possible antiscaring effect. However, the precise pathological mechanism still remain unknown. We questioned whether asiaticoside might alleviate the formation of hypertrophic scar by affecting the expression of Transform growth factor β (TGF-β)/Smad signaling. Aims:  To investigate the effect of asiaticoside on the expression of TGF-β/Smad signaling in the rabbit ear model of hypertrophic scar and to clarify the mechanism of asiaticoside on the scar treatment. Methods:  The rabbit model with hypertrophic scar was created and applied topically with a low-dose (0.5%) or high-dose (1%) asiaticoside three times daily for 1, 2 or 3 months and then we examined the changes of macroscopic and histopathologic characteristics of scars, and the expression of TGF-β1 and Smad protein was studied by applying reverse transcription-polymerase chain reaction and western blotting. Result:  Asiaticoside could remarkably alleviate the scar in the rabbit ear model. Western blotting showed that the asiaticoside could decrease TGF-β1 expression, and further study revealed that asiaticoside could remarkably enhance the expression of inhibitory Smad7, but it had no effect on the expression of Smad2. Conclusion:  Asiaticoside suggested a possible antiscaring effect probably by enhancing the expression of inhibitive Smad7.