Imiquimod Inhibit Scar Formation In Rabbit Ear Hypertrophic Scar Model

Objective:In this study, we evaluated the inhibitory effect and mechanism of imiquimod on rabbit ear hypertrophic scar formation.Methods:Ten New Zealand White rabbits were employed in this study. Rabbit ear hypertrophic scar model was created on the basis of the previous literatures reported by Morris, Huiquan Li and Haifeng Zeng. We cut six round wounds in each rabbit ears ventral that diameter of1cm, bilateral symmetry, peel the full-thickness of skin and film layer of cartilage. All the left ear wounds were treated with5%imiquimod cream. The control group contains all the right ear wounds and were treated with vaseline ointment at the same time. Every wounds were applied cream after healing, once a day.Both of the groups were harvested at the same time on days14、21、28、35and42after operation. Two rabbits were killed by air embolism every time. The specimens were cut along the edge outside the scar at0.5cm ring, then cut through the most thickest point in half. HE (Hematoxylin-eosin) staining and Masson trichrome staining were performed after fixing to observe morphological differences. Measured the expression of Col-Ⅰ (Collagen-Ⅰ), IFN-γ(Interferon-γ) and IL-4(Interleukin-4) with Real-time PCR.Results:The sections of HE and Masson show that compared with the blank control group, the level of the collagen deposition was significantly reduced in the treated group (P＜005). The expression of Col-Ⅰ, and IL-4were distinctly down-regulated in the treatment group. The expression of IFN-y increased compared with the control group.Conclusion:Imiquimod may inhibit scar formation by means of regulate the expression of IFN-y and IL-4.