[Dermo-epidermal interactions and skin pharmacology].

Reconstruction of a living skin equivalent provides an in vitro model for the study of skin biology and pharmacology in a tissue organization whose cells differentiate similarly to skin cells in the body. This simplified skin equivalent, composed of normal or abnormal cells, is obtained in two steps: formation of a dermal equivalent is achieved first and this dermis is then covered with an epidermal equivalent. Each of these tissues, as well as the interactions between them, can then be studied. Using this model, we have demonstrated that normal fibroblasts promote epidermal growth, that psoriatic fibroblasts induce increased proliferation of normal keratinocytes, and that the effects of pharmacological agents (such as retinoids) on keratinocyte growth are modulated by fibroblasts.