Distinct patterns of collagen gene expression are seen in normal and keloid fibroblasts grown in three-dimensional culture.

The purpose of this study was to examine collagen gene expression in various types of scar fibroblasts as well as normal fibroblasts in a novel three-dimensional culture system and to compare them with those in a monolayer culture system. Cells in three-dimensional culture formed multiple layers within the self-produced dense extracellular matrix and formed a dermis-like structure. In monolayer culture, both normal and scar fibroblasts continued to express high levels of mRNA for pro alpha 1(I) and pro alpha 1(III) collagens. However, in three-dimensional culture, the mRNA levels gradually declined in normal fibroblasts. In contrast, mRNA levels remained high in keloid and hypertrophic scar fibroblasts. Atrophic scar fibroblasts demonstrated similar changes to normal fibroblasts in three-dimensional culture. When we compared mRNA expression in fibroblasts from the centre and the edge of hypertrophic scar, cells from the centre showed a persistently decreased level of collagenase mRNA expression. These results suggest that the mRNA expression pattern of pro alpha 1(I) and pro alpha 1(III) collagens varies depending on the culture system. Fibroblasts from keloids and hypertrophic scar may have a defective system of down-regulation in extracellular matrix metabolism.