In vitro model systems for studying the impact of organic chemicals on the skin barrier lipids.

This paper describes two synthetic lipid models designed to replace human stratum corneum (SC) in studies of the impact of volatile organic chemicals on the molecular organization of the skin barrier lipids. The models built upon previously developed self-assembled lipid membranes which have composition and 3D organization similar to those of the lipid matrix in SC. In one model the target chemicals were incorporated in the lipids before their self-assembly, and in the other one they were applied on top of a preformed lipid membrane. The chemicals could be incorporated within the model membranes in quantities close to those reached within human SC upon heavy surface loading. The dose-dependent effects of the chemicals on the lateral molecular organization in the models were qualitatively identical to those observed by infrared spectroscopy in human SC. The models facilitated the interpretation of X-ray diffraction profiles used to determine the nature of the interactions between the chemicals and the lipid lamellae and the position of the exogenous molecules within the unit cell of the lipid phases. These model systems are suitable for in vitro studies in the areas of skin biophysics, dermatology, transdermal drug delivery, and risk assessment.