The Lipid Organisation in Human Stratum Corneum and Model Systems

The primary function of the skin is to act as a barrier against unwanted influences from the environment. The barrier function of the skin is located in the superficial of the skin, the stratum corneum. The stratum corneum consists of dead cells filled with keratin and water, which are embedded in lipid regions. The lipid regions are the only continuous structure in the stratum corneum. For this reason the lipid regions are considered to be very important for the barrier function. The main lipid classes are ceramides, cholesterol and free fatty acids. In this paper the lipid organisation in human stratum corneum is reviewed. In addition, the role the various lipid classes play in the lipid organisation will be discussed using mixtures prepared from either native human ceramides or synthetic ceramides. Finally a model, referred to as the stratum corneum substitute, is described in which the lipid organisation, composition and barrier function can be examined.