Establishment of a cell line with phenotypes of chondrocyte from a human osteogenic sarcoma of the mandible

We have succeeded in transplanting a human osteogenic sarcoma of the mandib le into athymic mice. The transplanted tumor showed marked chondrogenesis a nd mineralization. Recently, a cell line (USAC) with phenotypes of chondroc yte has been established from the transplanted tumor. USAC cells were stell ate or spindle-shaped in sparse culture, but polygonal or spherical at sub- confluency to confluency. In long-term culture, the cells were condensed an d calcified nodules were formed. Production of types I, II and X collagen w ere detected by immunohistochemical staining and Western blot analysis. Typ e I collagen was strongly expressed in the stellate or spindle-shaped cells . Although type II collagen was usually present in all cells during culture , it was strongly stained in polygonal cells at confluency. Type X collagen was seen in large polygonal cells around calcified nodules. Marked [S-35]- sulfate uptake and metachromasia were seen at the confluent stage and in th e nodule. The cells around the nodules were positive for alkaline phosphata se, and the center of the nodules was stained with alizarin red. The potent iality of cartilage formation was confirmed by in vivo experiments using a diffusion chamber in athymic mice. These observations indicate that USAC ce lls maintain characteristics of chondrocyte progenitor cells and thus may s erve as a useful model to study the sequential events of chondrogenesis and the process of morbid endochondral calcification. This experiment also dem onstrated that transplantation of tumor tissue into athymic mice is a conve nient strategy for establishment of a cell line.