New formulation of chemical peeling agent: histological evaluation in sun-damaged skin model in hairless mice

Abstract

Background: chemical peelings injure the superficial skin, which is then restored by healing of the wound. Objectives: to document the acute and chronic histological changes produced by applying chemical peeling agents used clinically to the UVB-irradiated skin of hairless mice, which served as a model of sun-damaged skin. Design: three chemical peeling agents, 30% salicylic acid, dissolved in macrogol (a new formulation), 35% trichloroacetic acid (TCA) dissolved in distilled water and 20% glycolic acid dissolved in glycerin were applied to the backs of UVB-irradiated hairless mice. Untreated, irradiated areas of skin served as controls. Specimens were evaluated histologically at 3, 14, 28, and 70 days. Results: chronic UVB irradiation produced an irregular hypertrophy of the epidermis. The treated areas of irradiated skin recovered by day 70. At 28 days, all skin specimens treated with chemical peeling agents exhibited a unique connective tissue layer composed of fine collagen fibers beneath the epidermis. While 35% TCA produced severe tissue damage marked by inflammation up to day 14, no inflammatory infiltrates were seen with 30% salicylic acid in macrogol at 70 days. Conclusions: chemical peeling with 30% salicylic acid dissolved in macrogol led to reorganization of the epidermis and a rebuilding of the superficial dermal connective tissue important in reducing wrinkles, and without evidence of inflammatory infiltrates in an animal model of sun-damaged skin. Findings suggest a possible clinical benefit.