Cellular Interactions In Vitro With Cells Derived From Tumors Induced by Murine Sarcoma Virus (Harvey)

Summary

Murine sarcoma virus (Harvey) [MSV(H)] rapidly induces tumors at the site of inoculation when injected intramuscularly into mice. Cells from such a tumor were established in culture. The primary culture in plastic dishes contained small, densely staining cells associated with fibroblasts and macrophages. On serial passage, the macrophages disappeared, and the fibroblasts formed a monolayer covered by small, densely staining spindle cells. By the ninth passage, the fibroblasts did not form a monolayer, and the individual, isolated fibroblasts acted as centers of growth for the spindle cells, which formed large cellular aggregates. When the same cells were plated in collagen-coated dishes, the spindle cells did not aggregate in the characteristic pattern. As the cultures growing on collagen approached confluence, large, multinucleate strap cells appeared. Clones of the small, spindle cells were grown on collagen, and on confluence they fused into strap cells. Evidence shows that the spindle cells were probably primitive mesenchymal cells which eventually developed myogenic properties, and that the large, multinucleate strap cells were myotubes. The spindle cells and the myotubes actively synthesized MSV. The histogenesis of MSV (H)-induced mouse tumors is discussed in relation to these findings.