Skin constructs for replacement of skin tissues for in vitro testing.

Reconstructed human skin equivalents as an alternative to animal experimentation offer not only a way to concede to demands of regulatory authorities, animal welfare organizations, consumers and scientists, but also provide a means to improve and extend our knowledge on biological processes in the skin. Presently, various skin reconstructs are available composed either of the epidermal compartment only or of both the epidermal and dermal compartments. Within each compartment various types of cells can be incorporated, including keratinocytes, melanocytes and Langerhans cells in the epidermal, and fibroblasts and endothelial cells in the dermal compartment. The quality of the human skin equivalents has now reached a point that their suitability for skin toxicity testing will make great progress. Next to the field of toxicity and safety standards, skin equivalents offer a well-characterized model for studies of the basic skin biology, wound repair, regulation of melanogenesis, pathogenesis of skin diseases and skin cancer.