ABSTRACT
Background@#Adiponectin is an adipose-derived hormone that plays a role in various metabolic diseases. We previously demonstrated that adiponectin inhibits melanin synthesis through adenosine monophosphate-activated protein kinase (AMPK) activation in melanocytes. However, melanocytes can be affected by neighboring keratinocytes, and the effect of adiponectin on these functional units has not been investigated. @*Objective@#We investigated the effect of adiponectin on melanogenesis in co-cultured models of normal human melanocytes (NHMs), normal human keratinocytes (NHKs), and human dermal fibroblasts (HDFs), and the effect of adiponectin on melanin content in human skin tissues. @*Methods@#Quantitative real-time polymerase chain reaction (qPCR) was performed for tyrosinase and microphthalmia-associated transcription factor (MITF). The degree of phosphorylation of AMPK, cAMP response element binding protein (CREB), and AKT was evaluated by western blot assay, and Fontana-Masson staining was performed on cultured human skin tissues. @*Results@#Adiponectin decreased the melanin content in the co-culture models of NHMs with NHKs, NHMs with HDFs, and NHMs with both NHKs and HDFs. qPCR revealed that both tyrosinase and MITF were decreased after adiponectin treatment in the co-culture system. Following adiponectin treatment, AMPK was activated in all cell groups; however, the phosphorylation of CREB was decreased in HDFs and NHKs. The phosphorylation of AKT was decreased in only NHMs. In the experiment with human skin tissues cultured ex vivo, the densitometric analysis of Fontana-Masson staining revealed that adiponectin treatment reduced the melanin level of ultraviolet-irradiated human skin tissues. @*Conclusion@#Adiponectin inhibited melanogenesis in both co-culture models and human skin tissues ex vivo.
ABSTRACT
BACKGROUND: Fractional laser resurfacing treatment has been extensively investigated and is widely used. However, the mechanism underlying its effects is poorly understood because of the ethical and cosmetic problems of obtaining skin biopsies required to study the changes after laser treatment. OBJECTIVE: To evaluate the usefulness of human skin explants for the investigation of fractional photothermolysis. METHODS: Full-thickness discarded skin was treated in 4 ways: no treatment (control), fractional carbon dioxide laser, fractional Er:YAG laser, and fractional 1,550-nm erbium-doped fiber laser. Both treated and non-treated skin samples were cultured ex vivo at the air-medium interface for 7 days. Frozen tissue was sectioned and stained with hematoxylin & eosin for histologic examination and nitro blue tetrazolium chloride for viability testing. RESULTS: Skin explants cultured for up to 3 days exhibited histologic changes similar to those observed in in vivo studies, including microscopic treatment zones surrounded by a thermal coagulation zone, re-epithelialization, and formation of microscopic epidermal necrotic debris. However, the explant structure lost its original form within 7 days of culture. The viability of skin explants was maintained for 3 days of culture but was also lost within 7 days. CONCLUSION: The skin explant model may be a useful tool for investigating the immediate or early changes following fractional photothermolysis, but further improvements are required to evaluate the long-term and dermal changes.