The effect of low-intensity cold atmospheric plasma jet on photoaging-induced hyperpigmentation in mouse model

Background: Cold atmospheric plasma (CAP) produces reactive oxygen/nitrogen species (RONS) in the target and can induce cytoprotective effects by activating hormesis-related pathways when its intensity is in the low range. Objectives: The aim of this study is to evaluate the effect of low-intensified CAP (LICAP) on skin with photoaging-induced hyperpigmentation in an animal model. Methods: Changes in cell viability and RONS production following LICAP treatment were measured. For the in vivo study, 30 hairless mice underwent antecedent photoaging induction followed by the allocated therapy (i.e., LICAP, topical ascorbic acid (AA), or both). During the first 4 weeks of the treatment period (8 weeks), ultraviolet (UV)-B irradiation was concurrently administered. Visual inspection and measurement of the melanin index (MI) were performed to assess the change in skin pigmentation at Weeks 0, 2, 4, 6, and 8. Results: RONS production increased linearly until the saturation point. Cell viability was not significantly affected by LICAP treatment. At Week 8, MI was significantly decreased in every treatment group compared with the values at Week 0 and Week 4. The treatment effect of the concurrent therapy group was superior to that of the LICAP and AA groups. Conclusion: LICAP appears to be a novel modality for photoprotection and pigment reduction in photodamaged skin. LICAP treatment and topical AA application seem to exert a synergistic effect.