Use of an in vitro skin model to study the dermo-epidermal junction

Some years ago, prior to human use of new cosmetic products, in vivo animal tests were conducted in order to screen for safety and efficacy. The tenets of ethical animal testing call for practice of the three R\’s of refinement, reduction and replacement of animal tests. Therefore, a growing need exists for rapid and reliable in vitro methods for safety and efficacy screening of new dermato-cosmetological products. Three-dimensional organotypic skin models exhibit in vivo-like morphological, metabolical, and growth characteristics which are uniform and highly reproducible. These skin-like tissues consists of organized basal, spinous, granular and cornified epidermal layers analogous to those found in vivo, and they can provide alternative models to replace animal and human experiments. In the present study, these organotypic cultures have allowed to determine the effects of the test product in the basement membrane of skin, also called dermoepidermal junction, which is responsible of the contact between epidermis and dermis, and plays an important role in the maintenance of tissue architecture and normal skin functions. In the epidermis of the skin, basal keratinocytes adhere to the basement membrane through α6β4 integrin which binds to Laminin-5, an interaction necessary for hemidesmosome formation and basement membrane stability. Hemidesmosomes are anchoring junctions of the cell to a non-cellular substrate that play a critical role in stabilising the association of the dermis with the epidermis. The importance of the hemidesmosome junctions for the epidermis attachment is clearly demonstrated by the fact that in a variety of blistering diseases, there is a disruption of the hemidesmosomal complex. Several studies also confirm that there are ch anges occurring at this dermal-epidermal junction during the course of age. Serilesine is a Laminin-like peptide that was found to be active in promoting fibroblast and keratinocyte proliferation and therefore this peptide may play an important role in skin. In this study, Serilesine has been tested in order to determine its effects on the basement membrane proteins and on hemidesmosome formation. To this purpose, the effect of Serilesine on Laminin-5 and α6-integrin expression and hemidesmosome formation was determined in the skin model. Poster Use of an in vitro skin model to study the dermo-epidermal junction Núria Almiñana and Eva Martinez