Chondrocytes embedded in collagen gels maintain cartilage phenotype during long-term cultures.

Chondrocytes isolated from sterna of 13-day-old chick embryos were cultured in vitro within collagen gels for six weeks. Under these culture conditions, chondrocytes assumed a rounded morphology, accumulated metachromatic matrix, and took on the cytological characteristics of in vivo cartilage cells. Most of the glycosaminoglycans synthesized were deposited within the collagen gels, and the rate of glycosaminoglycan synthesis was maintained over five weeks. Throughout the study, the major collagen synthesized was Type II. This cell-culture system, using collagen gels, provides chondrocytes with a suitable environment in which to accumulate synthesized matrix macromolecules and preserve their differentiated phenotype in vitro.