In vitro phototoxicity test using artificial skin with melanocytes

Background: Exposure to ultraviolet radiation (UVR) has been shown to induce cutaneous biological changes and phototoxic reactions. Objective: This study was designed to evaluate the usefulness of artificial skin (AS) composed of keratinocytes and melanocytes as an in vitro phototoxicity model for topical agents. Materials and methods: ASwas manufactured with three-dimensionally cultured keratinocytes and melanocytes on a de-epidermized dermis (DED). The photobiological responses in AS with and without melanocytes were comparatively examined after ultraviolet A (UVA) exposure. Three test chemicals (8-methoxypsoralen, 6-methylcoumarin and tetracycline) were topically applied onto the AS with melanocytes and after UVA irradiation, the released inflammatory cytokines (IL-1α, IL-β and IL-6) were analyzed. Results: AS with melanocytes showed better epidermal structures, stronger resistance to UVA exposure and photobiological responses closer to in vivo human skin. Releases of inflammatory cytokines were well correlated with the increased phototoxicities of test chemicals. Among the measured cytokines, IL-6 could be the most reliable in vitro marker indicative of phototoxic potential, because it showed statistically significant increase only in case of concurrent exposure to chemicals and UVA. Conclusion: The AS with melanocytes may be a useful tool especially for examining UV-induced cutaneous changes and a promising in vitro phototoxicity test model for topical agents.