616 A water-in-oil emulsion with pH 4 improves structure of lipid lamellae and restores disrupted epidermal barrier in the elderly

Abstract

Models of human epidermis are widely employed for basic studies of skin biology and in the development of drugs and cosmetics, but epidermal equivalents prepared with passaged keratinocytes are typically only 10-20 mm thick, whereas full-thickness human epidermis can be up to 100 mm thick. Our established mathematical model of epidermal homeostasis predicted that the undulatory pattern of the papillary layer beneath the epidermis is a key determinant of epidermal thickness. Here, aiming to develop a more physiologically realistic epidermal model, we tested this prediction by seeding human keratinocytes on polyester textiles with various fiber-structural patterns in culture dishes exposed to air. Textile substrate with fiber thickness and inter-fiber distance similar to those of human papillary layer proved most effective, affording a three-dimensional epidermal-equivalent model with thick stratum corneum and intercellular lamellar lipid structure. Cells located around fibers of the textile were proliferating, as indicated by BrdU staining and expression of melanoma-associated chondroitin sulfate proteoglycan. Fillaggrin, loricrin, claudin 1 and ZO-1 were all appropriately expressed. Silencing of the transcriptional coactivator YAP (Yes-associated protein) with siRNA disturbed construction of the three-dimensional structure. This work provides simple methodology for production of high-quality, low-cost epidermal-equivalent models using passaged keratinocytes.