The Mechanism And Clinical Application Of Botulinum Toxin Type A In Treating Hypertrophic Scar

Fibroblasts are the main mechanism of scar formation.In Pathological conditions,fibroblast proliferation,excessive deposition of collagen,myofibroblast formation,cell apoptosis reduction,hypertrophic scar(HTS)formation in the process of wound healing There are lots of different methods for treating scars,of which,intralesional corticosteroidsinjection in lesions is the most convenient one.However,there are many side-effects,such as stunted growth,osteoporosis,cataract,and hypertension As we all known,Botulinum toxin A(BTXA)has been very popular in clinical application in the last decades,and no obvious side effects was found.It could inhibit the scar formation after wound to a certain extent in some random clinical trials.On one hand,BTXA reduces muscle movement decreasing the tension of incision,on the other hand,BTXA may directly inhibit the fibroblasts.The mechanism of the former one was obvious,however,for the latter,therewas no effective evidenceObjective1 Evaluation the suitable concentration of BTXA in inhibiting fibroblasts.In which signal pathways and targets,BTXA may take effect in the inhibition of fibroblasts2 To study the effect of W-plasty with BTXA in the treatment of facial scarMethods1 Fibroblasts were isolated from tissue specimens of HS.Different dosage of BTXA were added into groups.Growth condition of fibroblasts was observed at 24 h,48 h,72 h,96 h after BTXA effected.Changes of a-SMA,FAK,p-FAK,YAP,p-YAP were detected by Western blot and TGF-?1 by ELISA.Ran FAK expression vectors,the level of a-SMA,FAK,p-FAK,YAP,p-YAP were detected by Western blot,and YAP was detected by immunofluorescence assay(IFA)2 40 cases were included,20 cases in the treatment group were treated with the union methods,20 cases in the control group were treated with traditional method.Evaluating the therapeutic effect by Visual Analogue Scale(Visual Analogue Scale,VAS)Results:1 The growth activity of fibroblasts was decreased in different degree with two different concentrations of BTXA treated for 24h,48h,72h,96 h.The ability of the group 1(BTXA 1U/106Cells)in inhibiting fibroblast was the strongest.Besides,the level of TGF-?,?-SMA,FAK,p-FAK,YAP and p-YAP between this group and the control group were statistically significant.After 48 h,both level of FAK protein and protein phosphorylation by fluorescence detection were reduced in group 1.The level of YAP by fluorescence expression was decreased obviously.2 The successful follow-up of 20 cases in the treatment group,the effect was satisfied.The difference of VAS score between the treatment group and control group was significant.Besides,the percent of VAS score of experiment group above nine points was accounted for 90%.Conclusion:1 W-plasty combined with botulinum toxin type A could treat the facial scar great.The concentration of BTXA in group 1 was seemed to be the best one to inhibit the growth of fibroblasts.2 The mechanism of BTXA inducing the apoptosis of fibroblasts may via the TGF-?/YAP signaling pathways and FAK was the target.