Botulinum Toxin A for the Treatment of Keloids

Abstract

Keloids are the result of excessive scar tissue formation. Besides their poor aesthetic appearance, keloids can be associated with severe clinical symptoms such as pain, itching, and rigidity. Unfortunately, most therapeutic approaches remain clinically unsatisfactory. Recently, injections with botulinum toxin A (BTA) were proposed for the treatment of established keloids in a clinical trial. In this study, we aimed to verify the effects of intralesional BTA for the treatment of therapy-resistant keloids using objective measurements. In addition, the underlying molecular mechanisms were investigated using cultured keloid-derived fibroblasts. Four patients received BTA (doses varying from 70 to 140 Speywood units per session) injected directly into their keloids every 2 months for up to 6 months. Differences in height and volume were evaluated clinically and measured with a 3-D optical profiling system. Keloid-derived fibroblasts were treated with different concentrations of BTA, and expression of collagen (COL)1A1, COL1A2, COL3A1, TGF-β1, TGF-β2, TGF-β3, fibronectin-1, laminin-β2, and α-SMA was determined by real-time quantitative PCR. MTT and BrdU assays were used to analyze the effects of BTA on fibroblast proliferation and metabolism. Intralesional administration of BTA did not result in regression of keloid tissue. No differences in expression of ECM markers, collagen synthesis, or TGF-β could be observed after BTA treatment of keloid fibroblasts. In addition, cell proliferation and metabolism of keloid fibroblasts was not affected by BTA treatment. The suggested clinical efficiency of intralesional BTA for the therapy of existent keloids could not be confirmed in this study. Based on our data, the potential mechanisms of action of BTA on keloid-derived fibroblasts remain unclear.