Photoprotection against UV-induced damage by skin-derived precursors in hairless mice

Background: Skin photodamage is associated with UV-induced overproduction of reactive oxygen species (ROS) and the inactivation of NF-E2-related factor 2 (Nrf2). Skin-derived precursor cells (SKPs), a population of dermal stem cells, are considered to be involved in wound repair and skin regeneration through the activation of Nrf2. However, no reports concentrate on the treatment of skin photodamage with SKPs. Objective: To investigate the photoprotective role of SKPs against UV-induced damage in mice. Methods: Fifty Balb/c hairless mice were divided into five groups (n = 10), namely, normal (no intervention), model, prevention, treatment, and control groups. The latter four groups were dorsally exposed to UVA + UVB irradiation over a 2-week period. Mice in the prevention group received weekly SKP injections for 2 weeks the day before irradiation. Mice in the treatment and Hanks groups received a two-time injection of SKPs and Hanks, respectively, after irradiation. One week after final intervention, skin appearance, pathological alterations, and oxidative indicators were evaluated by enzyme-linked immunosorbent assay, immunohistochemical analysis, and western blotting. Results: After irradiation, lesions were observed on the dorsal skin of mice, including erythema, edema, scales, and wrinkles; however, these were significantly ameliorated by subcutaneous SKP injection. Hyperkeratosis, acanthosis, and spongiosis in the epidermis, as well as dermal papillae edema and inflammatory cell infiltration, were observed in both model and control groups; however, these conditions resolved with either pretreatment or posttreatment with SKPs. In addition, SKPs increased Nrf2, heme oxygenase-1, glutathione peroxidase, superoxide dismutase, catalase, and gluthathione expression, while decreasing levels of ROS, MDA, and H2O2. Conclusions: These findings suggest that SKPs have a photoprotective role against UV-induced damage in mice, which may be associated with their ability to scavenge photo-oxidative insults and activate Nrf2.