Comparison of Steroid and Botulinum Toxin Type A Monotherapy with Combination Therapy for Treating Human Hypertrophic Scars in an Animal Model

The authors evaluated the efficacy of a combined regimen of botulinum toxin type A (Botox) and a steroid (triamcinolone acetonide) for treating hypertrophic scars in comparison with the treatment with each drug alone.Twenty excised human hypertrophic scar fragments obtained from surgically treated burn patients were divided into four groups: negative control (group A), triamcinolone alone (group B), Botox alone (group C), and a combination of triamcinolone and Botox (group D). These specimens were implanted into the backs of nude mice after intralesional injection from each group and were observed for 4 weeks. In total, 12 mice and 48 scars were studied. After 4 weeks, the hypertrophic scars were removed from the backs. The authors compared the scar weights, decorin staining, and the Cell Counting Kit-8 assay to evaluate treatment efficacy.Significant differences in scar weight reduction were observed among the four groups (group A, 10 percent; group B, 17 percent; group C, 23 percent; and group D, 30 percent; p < 0.05). Treatment groups (groups B, C, and D) showed strong decorin staining. Significant differences in reduction of fibroblast proliferation were observed among the four groups (group A, 0.58; group B, 0.44; group C, 0.21; and group D, 0.08; p < 0.05). Botox or triamcinolone intralesional monotherapy showed significant therapeutic efficacy compared with the control group. The combined therapy further exhibited a significant therapeutic effect compared with monotherapy.This study indicates the potential of Botox and triamcinolone when combined for intralesional therapy in treating hypertrophic scars.