ABSTRACT
Since the European Union (EU) announced their animal testing ban in 2013, all animal experiments related to cosmetics have been prohibited, creating a demand for alternatives to animal experiments for skin studies. Here, we investigated whether an ex vivo live porcine skin model can be employed to study the safety and skin barrier-improving effects of hydroxyacids widely used in cosmetics for keratolytic peels. Glycolic acid (1-10%), salicylic acid (0.2-2%), and lactobionic acid (1.2-12%) were used as representative substances for α-hydroxyacid (AHA), ß-hydroxyacid (BHA), and polyhydroxyacid (PHA), respectively. When hydroxyacids were applied at high concentrations on the porcine skin every other day for 6 days, tissue viability was reduced to 50-80%, suggesting that the toxicity of cosmetic ingredients can be evaluated with this model. Based on tissue viability, the treatment scheme was changed to a single exposure for 20 min. The protective effects of a single exposure of hydroxyacids on skin barrier function were evaluated by examining rhodamine permeability and epidermal structural components of barrier function using immunohistochemistry (IHC) and immunofluorescence (IF) staining. Lactobionic acid (PHAs) improved skin barrier function most compared to other AHAs and BHAs. Most importantly, trans-epidermal water loss (TEWL), an important functional marker of skin barrier function, could be measured with this model, which confirmed the significant skin barrier-protective effects of PHAs. Collectively, we demonstrated that the ex vivo live full-thickness porcine skin model can be an excellent alternative to animal experiments for skin studies on the safety and efficacy of cosmetic ingredients.
Subject(s)
Skin Physiological Phenomena , Skin/metabolism , Animals , Biomarkers , Epidermis/drug effects , Epidermis/metabolism , Fluorescent Antibody Technique , Histocytochemistry , Humans , Hydroxy Acids/chemistry , Hydroxy Acids/pharmacology , In Vitro Techniques , Permeability , Rhodamines/pharmacology , Salicylic Acid/chemistry , Salicylic Acid/pharmacology , Skin/cytology , Skin/drug effects , Skin Physiological Phenomena/drug effects , Swine , Tissue Culture TechniquesABSTRACT
The application of rice wine on skin is known to have beneficial effects such as enhancement of the skin barrier function and skin whitening. In this study, we focused on examination of the anti-aging effects of rice wine. The treatment of fibroblasts with rice wine in vitro increased the expression of procollagen and laminin-5, a key basement membrane component in cultured human fibroblasts. Rice wine significantly reduced the expression of UV-induced matrix metalloproteinase-1 (MMP-1) in a dose-dependent manner in both cultured human fibroblasts and keratinocytes. In addition, treatment with rice wine decreased UV-induced tumor necrosis factor-alpha (TNF-alpha) production in human keratinocytes. An in vivo study using hairless mice showed that topical application of rice wine protected mouse skin from photoaging. Thus, we suggest that rice wine may have potential as an effective agent for the prevention and treatment of UV-induced skin aging.
