The Study On The Mechanism Of Oleanolic Acid Treat Human Hypertrophic Scar

Hypertrophic scarring, a common proliferative disorder of dermal fibroblasts, is a result of collagen overproduction and excessive deposition of extracellular matrix (ECM), and may occur in healing wounds caused by deep burn, inflammatory reactions, and trauma. Patients with hypertrophic scars often report itching and pain, and experience serious functional and cosmetic problems, which are caused by a variety of complications, including compression, sensation of stiffness, loss of joint mobility and anatomical deformities. When an exuberant scar occurs, there are many treatment choices. However, there is no consensus about the best treatment to produce complete and permanent improvement of scars with few side-effects. It has been generally recognized that natural drugs can play a unique therapeutic role in the treatment of many diseases.Hypertrophic scar fibroblasts were cultured from HS tissue. The effect of oleanolic acid (OA) on cell proliferation was masured by MTT assay and the growth inhibition rate was calculated. The further detection of fibroblasts apoptosis were measured by Flow Cytometer. The Annexin-V/PI double staining was used for apoptosis rate detection, PI was used for content of DNA, DCFH-DA was used for ROS detection, Rhodamine 123 was used for mitochondrial membrane potential. The signal pathway modulating FB apoptosis including p38MAPK and JNK pathway and the key protein, caspase-3 and AIF, in apoptosis were studied by Western-blot. HS in rabbit ear model were established to verify the effect of OA. The scars in rabbit ears were randomly divided into 5 groups, model group, low-dose group (2.5%, w/v), middle-dose group (5%, w/v), high-dose (10%, w/v) and positive control group (contractubax), and normal group unoperated. OA was applied once daily to the scar for 22 days. On postoperative day 28, the scars were excised, and the tissue used for histological examination and assays of the levels of collagensⅠandⅢ, matrix metalloproteinase (MMP)-1 and transforming growth factor (TGF-β1). The scar elevation index (SEI) was also determined. The results show that OA has anti-proliferation effect on HSFBs in a dose- and time-dependent manner, and the FCM results indicate that OA induced dose-dependent cell apoptosis, rather than by upregulating the ROS level. After treated with OA, the caspase-3 and AIF were activated, and the expression of p-p38 and p-JNK were upregulated. And in rabbit ear model, treatment with different concentrations of OA for 22 days significantly inhibited hypertrophic scar in rabbit ear tissue. Levels of TGF-β1,collangenⅠand collagenⅢwere significantly decreased and levels of MMP-1 drasticaly increased in the scar tissue. SEI was also significantly reduced. Histological findings showed significantly amelioration of the scar tissue.In conclution, OA could inhibit HSFBs preliferation and induce HSFBs apoptosis, suppresses hypertrophic scar in rabbit ear model and may be an effective cure for human hypertrophic scar.