Collagen biosynthesis by cells in a tissue equivalent matrix in vitro.

Collagen biosynthesis by fibroblasts and subsequent processing and polymerization have been studied in conventional monolayer cultures and in a new model system in vitro in which cells organize into a tissue like structure. While the bulk of the newly made collagen becomes tightly and selectively bound to the matrix of the tissue equivalent model, in monolayer cultures most of the collagen passes into the culture medium. Collagen biosynthesis appears to be regulated differently in cells of the tissue equivalent model as compared with monolayered cells. In the former there is a 6- to 8-fold decrease in collagen output even though overall protein synthesis per unit of DNA is twice as great as in monolayered cells. Cells grown in tissue lattices exhibit much higher collagenolytic activity than cells in monolayer suggesting the model may also be of special use for studying collagen turnover and matrix remodeling.