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Establishment of transplantable murine osteosarcoma cell line with endochondral ossification.

Osteosarcoma is defined as a malignant mesenchymal tumor in which tumor cells produce bone matrix. Osteosarcoma cell line (Nishi-Hirosaki osteosarcoma, NHOS) from a spontaneous soft tissue tumor in an athymic mouse was established. The cultured NHOS cells formed a monolayer consisting of spindle to polygonal cells without extracellular matrix formation or mineralization. In contrast, the transplanted NHOS tumor in immunodeficient mice consisted of short spindle and pleomorphic cells, associated with networks of calcified bone and osteoid matrices, as well as small foci of chondroid matrix. Pulmonary metastasis was detected in 22 (42.3%) out of the 52 tumor-bearing mice when NHOS cells were transplanted into the murine flanks. Pulmonary metastasis was detected in all mice (6/6) at post-injection days 21-49 when the cells were injected into the murine tail veins. The NHOS transplantable osteosarcoma cell line with ossifying ability would be useful to clarify the mechanisms of aggressive metastatic potential, as well as for studying the ossification process involved in cell-to-matrix interactions.