Scar Reducing Effect of the Silicone Gel Sheet with Verapamil in a Rabbit Model of Hypertrophic Scar

Abstract Purpose: One of the CCBs, verapamil is clinically effective for the treatment of HTS when injected via an intralesional route.¹ It is, however, a disadvantageous modality in that it causes pain, limits the indications and requires frequent outpatient visits. We have developed a novel treatment modality based on topical application of the silicone gel sheet (SGS) with verapamil microparticles at varying treatment doses. Thus, we examined its effects on hypertrophic scar (HTS) in a rabbit ear wound model. Methods and materials: We used ten New Zealand White (NZW) rabbits, where 80 wounds were created. We divided them into five groups (the control group, the pure SGS group, and the SGS+verapamil 0.25, 2.5 and 25 mg/g groups). Histopathologic findings were quantified based on the scar elevation index (SEI) and fibroblast and capillary counts. Results: There was a significant difference in the mean SEI, fibroblast counts, and capillary counts between five groups (the control group, the pure SGS group (Fig. 1), and the SGS+verapamil 0.25, 2.5 (Fig. 2) and 25 mg/g groups). (P < 0.05). The median SEI was significantly lower in the SGS+verapamil 2.5 mg/g group, as compared with the pure SGS group (1.2 vs. 2.2). The median number of fibroblasts was significantly lower in the SGS+verapamil 0.25 mg/g group, as compared with the pure SGS group (172.5 vs. 243). The median number of capillary lumina in the control group (29.5) was the significantly highest of the five groups. But there was no significant difference in the median number of capillary lumina between the pure SGS group, the SGS+verapamil 0.25 mg/g group, the SGS+verapamil 2.5 mg/g group and the SGS+verapamil 25 mg/g group (28.5, 18, 20 and 18, respectively). Conclusions: A topical application of the SGS with verapamil microparticles might be a novel, effective treatment method in a rabbit model of HTS.

Reference

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  Figure legends   Fig. 1. Histopathologic findings of the pure SGS group.       Fig. 2. Histopathologic findings of the SGS+verapamil 2.5 mg/g group.