광역동 치료를 이용한 비색소 털의 제모

Abstract

Lasers have been used for decades to remove dark hair. However, laser removal of nonpigmented hair is not possible, because blond or white hair lacks energy-absorbing chromophores. The aims of this study were to use photodynamic therapy (PDT) to remove nonpigmented hair and to investigate the mechanisms involved in it using an animal model. Methyl aminolevulinate cream was applied to the depilated backs of 7-week-old BALB/c mice. After 4-hr incubation, 630-nm light-emitting diode irradiation (74 J/cm2) was performed. Skin biopsy specimens were collected from mice after 15 min, 3 hr, 24 hr, 48 hr, 72 hr, 1 week, 2 weeks, and 3 weeks. Post-PDT histologic changes in nonpigmented hair follicles were investigated. Molecular changes were evaluated with either Western blot analysis or enzyme-linked immunosorbent assay. The efficacy of permanent hair removal was compared in white BALB/c and black C57BL/6 mice treated with PDT or 800-nm diode laser. A temporary, catagen-like transformation was observed in nonpigmented hair follicles after PDT. Within 3 weeks, anagen hair was regenerated. Keratin 15 staining in the bulge area and alkaline phosphatase staining in the dermal papilla were also observed throughout the 3-week period following PDT. Deoxynucleotidyl transferase-mediated UTP end labeling-positive cells were observed in the hair matrix from 3 hr to 3 days after PDT. The nuclei of hair matrix cells became basophilic and condensed after one session of PDT. One day after PDT, levels of interlukin-6, tumor necrosis factor-α, transforming growth factor-β1, superoxide dismutase 2, and cyclooxygenase-2 increased. Irradiation with an 800-nm diode laser did not achieve nonpigmented hair removal. Permanent removal of nonpigmented hair was achieved on a small portion of the mouse back after multiple PDT sessions. Removal of black hair using PDT was less efficient compared with 800-nm diode laser removal. Our results suggest that PDT can damage the nonpigmented hair matrix, but not stem cells or dermal papillae. Repeated PDT may impair the hair-regeneration capacity via a bystander effect on bulge stem cells or dermal papillae. PDT could be considered a new treatment option for nonpigmented hair removal.