Muriel Cario currently works at INSERM 1312, University of Bordeaux.  She has over 25 years' experience in the physiopathology of human skin pigmentation and tissue engineering. She is a board member of the European Society for Pigment Cell Research (ESPCR) and of the Cosm'actifs GDR.  She collaborates with academic teams and the cosmetics industry to develop new models for studying skin pathologies such as senile lentigo, melasma, vitiligo, melanoma and carcinoma, new methods for vectorizing active ingredients and to test new active molecules. She has published over 70 articles and chapters on skin models, their use in deciphering skin diseases and testing active ingredients. Dr Cario is co-director of Aquiderm, a technology transfer unit specialized in dermocosmetic products.

Skin models use to test active ingredients

The skin is a complex organ composed of 3 layers (epidermis, dermis and hypodermis) which enable it to perform its various functions: defense against external aggression, thermoregulation and vitamin D production. These layers are made up of cells with very specific properties and roles, such as keratinocytes, which ensure the structure of the epidermis, melanocytes, which produce melanin, the skin pigment, and dermal fibroblasts, which produce collagen and elastin. Skin characteristics differ according to age, photo-exposure and phototype (skin color). In cosmetics, only in vitro and ex vivo models can be used; animal experimentation is no longer authorized. There are various models of varying complexity, from simple models made with keratinocytes on polycarbonate filters to skin explants. Skin models can be produced on acellular or cellular supports, with one or more cells from the dermis and epidermis. They can also be chemically stimulated or genetically modified to reproduce various skin alterations such as age spots (senile lentigo). The choice of the right model depends on a number of parameters, such as the target of the molecule, the time required to obtain an effect and the markers studied. For example, to study a molecule active on age spots due to pigment accumulation in the epidermal basal layer, a model composed solely of keratinocytes and melanocytes is not necessarily suitable. In this presentation, we will review the different 3D models and their advantages.