Establishment of a Clonal Human Chondrosarcoma Cell Line with Cartilage Phenotypes

A clonal cell line with cartilage phenotypes and tumorigenicity during more than 3 years in culture was established from a human chondrosarcoma. In sparse cultures, the clonal line, named HCS-2/8, consisted of slightly elongated polygonal cells, which proliferated with a doubling time of 3.5 days. The cells became polygonal to spherical as they became confluent. After reaching confluence, the cells continued to proliferate slowly and formed nodules, which showed metachromasia when stained with toluidine blue. The nodules were three-dimensional in structure; cells were multilayered in the surface regions, overlying a thick layer of extracellular matrix, which showed metachromasia. Electron microscopically, the cells resembling chondrocytes in vivo were surrounded by an extracellular matrix consisting of thin collagen-like fibrils with numerous fine granules, presumably of proteoglycans. The cells actively synthesized proteoglycans as determined by [35S]sulfate incorporation. The hydrodynamic size of major proteoglycan monomers synthesized by the cells was that of so-called cartilage-specific proteoglycans, as determined by glycerol gradient centrifugation. Immunostaining identified type II collagen but not type I collagen. Fluorography and immunoblotting of collagens separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis also demonstrated the synthesis of type II collagen but not type I collagen. Inoculation of HCS-2/8 cells into athymic mice resulted in the formation of chondrosarcomas that resembled the original tumor. Because of having these characters, HCS-2/8 cells should be useful not only in studies on the differentiated phenotypes of human chondrocytes but also in basic studies on the diagnosis, treatment, and etiology of human chondrosarcomas.