Modulation of stratum corneum lipid composition and organization of human skin equivalents by specific medium supplements

Abstract

Our in-house human skin equivalents contain all stratum corneum (SC) barrier lipid classes, but have a reduced level of free fatty acids (FAs), of which a part is mono-unsaturated. These differences lead to an altered SC lipid organization and thereby a reduced barrier function compared to human skin. In this study, we aimed to improve the SC FA composition and, consequently, the SC lipid organization of the Leiden epidermal model (LEM) by specific medium supplements. The standard FA mixture (consisting of palmitic, linoleic and arachidonic acids) supplemented to the medium was modified, by replacing protonated palmitic acid with deuterated palmitic acid or by the addition of deuterated arachidic acid to the mixture, to determine whether FAs are taken up from the medium and are incorporated into SC of LEM. Furthermore, supplementation of the total FA mixture or that of palmitic acid alone was increased four times to examine whether this improves the SC FA composition and lipid organization of LEM. The results demonstrate that the deuterated FAs are taken up into LEMs and are subsequently elongated and incorporated in their SC. However, a fourfold increase in palmitic acid supplementation does not change the SC FA composition or lipid organization of LEM. Increasing the concentration of the total FA mixture in the medium resulted in a decreased level of very long chain FAs and an increased level of mono-unsaturated FAs, which lead to deteriorated SC lipid properties. These results indicate that SC lipid properties can be modulated by specific medium supplements.

Effects of Freezing on Functionality and Physicochemical Properties of A 3D-Human Skin Model

“…Nevertheless, as reported by other groups, these skin substitutes showed a decreased permeability barrier compared with human skin when performing diffusion studies [46]. Our results showed that cumulative amounts were not significantly different between fresh and frozen human skin samples where both showed good barrier against benzoic acid (Figure 2A), which is in accordance with the literature [44].…”

Non-animal models of epithelial barriers (skin, intestine and lung) in research, industrial applications and regulatory toxicology

“…Although all lipid classes present in native human skin are also present in HSEs, there is a deviation in free lipid composition and organization compared to native human skin. The most important of such deviations are a high level of unsaturated fatty acids, shorter lipid chain lengths (Mojumdar et al, 2014;Thakoersing et al, 2013Thakoersing et al, , 2015 and an imbalance in the level of ceramide subclasses (Thakoersing et al, 2012). These changes in lipid composition are expected to contribute significantly to the impaired skin barrier of HSEs (Mojumdar et al, 2014).…”

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“…According to Thakoersing et al [46] stratum corneum lipids of skin substitutes adopt a mainly hexagonal packing, whereas human stratum corneum lipids are arranged in a more dense orthorhombic packing [46]. However, ATR-FTIR results showed a good lipid organization correlation of both conditions: …”

“…At 28 °C, no significant differences in terms of lipid composition and organization were observed between fresh and frozen/thawed skin biopsy #23 (2849. 46 ). Finally, no significant differences were observed in this range of temperatures (Figure3A).…”