Bone-forming cell line derived from embryonal carcinoma cells.

The use of established cell lines of various types has provided information on the properties of certain stem cells and on the conditions of their differentiation. No bone-forming cell line has so far been described. We report here the isolation, from in vitro differentiating teratocarcinoma cells, of a line which, on subcutaneous injection into syngeneic mice, gives rise to ossicles. The appearance of ossicles is preceded by the formation of a cartilaginous matrix, thus reproducing what has been described as endochondral differentiation. The ossicles obtained are rapidly colonized by host marrow, are non-malignant and stop growing 2 weeks after injection of the cells. In certain conditions, however, osteosarcomas, chondroosteosarcomas and fibrosarcomas can be obtained. From these tumours, cell lines have been isolated which retain in vitro the properties of the cells found in the tumour.