Use of agarose culture to measure the effect of transforming growth factor beta and epidermal growth factor on rabbit articular chondrocytes.

Nonneoplastic cell lines are unable to grow in soft agar. However, concomitant treatment of these cells with epidermal growth factor and transforming growth factor beta confers upon them anchorage independence. Since articular chondrocytes are unique as normal diploid cells that do have the capability of growing in soft agar, we tested whether transforming growth factor beta and epidermal growth factor could affect DNA synthesis and matrix production. In the presence of epidermal growth factor (5 ng/ml) concentrations of high-performance liquid chromatography-purified transforming growth factor beta at concentrations of 0.05-15 ng/ml induced a dose-dependent increase in DNA, to nearly double that of control cultures. A half-maximal effect was seen with transforming growth factor beta, 0.1 ng/ml, and epidermal growth factor, 5 ng/ml. Neither compound alone was mitogenic. In contrast, either transforming growth factor beta or epidermal growth factor alone was able to decrease synthesis of glycosaminoglycans and collagen. The data demonstrate that transforming growth factors can affect the behavior of nonneoplastic cells by modulating cell replication and the biosynthesis of two principal matrix components. In addition they support the hypothesis that these growth factors may play a role in the physiology of nonmalignant cells.