Use of Dermal Equivalent and Skin Equivalent Models for in Vitro Cutaneous Irritation Testing of Cosmetic Products: Comparison with in Vivo Human Data

AbstractThe development of new cosmetic formulations requires precise assessment of their safety and efficacy. Today, legislation imposes increasing measures of safety as well as the limitation of animal use for such testing (European Community directive 93/35/CEE). Subsequently, safety assessment protocols now focus on in vivo human volunteer tests and in vitro methods. In this study, in vivo testing consisted of 48 h patch tests on human volunteers followed by a clinical evaluation of irritation based on a visual scoring system including evaluation of erythema, edema, dryness, and vesicles. For in vitro testing to substantiate the safety of cosmetic products, we propose two three-dimensional models, a dermal equivalent (DE) and a skin equivalent (SE). The DE is composed of a porous collagen-glycosaminoglycans-chitosan dermal substrate populated by normal human fibroblasts. The SE is completed by a fully differentiated epidermis made by seeding normal human keratinocytes onto the DE.To evaluate the usefu...