Substrate membrane bearing close-packed array of micron-level pillars incrassates air-exposed three-dimensional epidermal equivalent model

Background: We showed previously that a thick three-dimensional epidermal equivalent can be constructed with passaged keratinocytes on a patterned surface. Material and Methods: We first carried out computer simulations of a three-dimensional epidermal equivalent model built on close-packed arrays of 10 mu m, 15 mu m, 20 mu m, 30 mu m, and 60 mu m diameter pillars. Based on these predictions, we evaluated epidermal equivalents built on a series of porous plastic membranes bearing arrays of pillars 15 mu m, 20 mu m, 25 mu m, 30 mu m, and 50 mu m in diameter. Results: The simulations predicted that a model having near-physiological thickness would be formed on 15 similar to 30 mu m pillars. In the results of in vitro study, the thickest epidermal equivalent was obtained on the 20 mu m pillars. Epidermal differentiation markers, filaggrin and loricrin, were expressed at the upper layer of the epidermal equivalent model, and tight-junction proteins, claudin-1 and ZO-1, were expressed on the cell membranes. BrdU-positive cells were observed at the base and also at the top of the pillars. Conclusion: The results of the study suggested that mathematical modeling might be a useful tool to guide biological studies.