Alternative Methods for Evaluating Skin Irritation Using Three-Dimensional Cultures

The Draize test has long been used as a method to evaluate skin irritancy. However, alternative methods have since been developed, in response to pressure from the ever-increasing movement of animal protectionists. Cell culture represents the most promising alternative method, and many trials of various kinds are under way, for example the monolayer culture, skin explant culture and three-dimensional skin equivalent culture. It is quite likely that better-qualified three-dimensional culture systems constitute the final goal in the search for alternative methods to evaluate skin irritancy. However, its effective validation will require not only further large-scale studies, but also the development of superior artificial skin models, with properties more closely resembling those of normal skin. In this review, we focus mainly on the skin equivalent culture method for measuring skin irritancy. Its superiority to other models as well as its problems and limitations are discussed.