The collagen lattice: a model for studying the physiology, biosynthetic function and pharmacology of the skin

Until recently, changes in cell physiology following application of pharmacological agents have been studied in vivo or in vitro using monolayered cells. Although both approaches have unique advantages, both have shortcomings. Now the development of a skin-equivalent model has provided a system for studying cell responses at the tissue and organ levels in vitro (Bell, Ivarsson & Merrill, 1979; Bell et al., 1981a, b). The in vitro tissue model can be made simple or complex with respect to eel! type heterogeneity and matrix constitution; ideally, however, it should resemble skin as closely as possible. It has the special advantage, unlike skin, of being able to survive for long periods in vitro. In this paper we compare the model morphologically with skin and review some aspects of the biosynthetic output of cells in the tissue equivalent with that of monoiayered cells. Finally we illustrate in a pharmacological study that the model can be used to provide new information that in vivo studies or monolayer cell studies cannot yield.