Tumor formation in the mammary fat pad upon injection of total bone marrow aspirates isolated from femurs containing metastatic tumor cells.

A. Experimental design to determine the tumorigenicity of disseminated human cancer cells in the bone marrow of mice previously injected with tumorspheres into the mammary fat pad. Bone marrow, aspirated from femurs of mice previously injected with tumorspheres into the mammary fat pad, was injected into the mammary fat pad of NUDE mice to determine the tumor-forming ability of dormant cancer cells in the bone marrow. B. Injection of 12.5×10⁶ cells/pad aspirated from the femurs of mice injected with tumorspheres resulted in large tumor formation in the mammary fat pad two months post-injection. C. Injection of 12.5×10⁶ cells/pad aspirated from the femurs of non-injected mice resulted in no tumor formation in the mammary fat pad three months post injection. D. Summary of tumor formation and metastasis for sample 5–9 BM, including ER/PR/Her2 status of patients samples from which the parental tumorspheres were first derived. E. Representative positive HNA staining of 5 µm paraffin-embedded sections of sample 5 BM tumors demonstrated the presence of human cells. F. No positive nuclear HNA staining of 5 µm paraffin-embedded sections of mouse kidney from non-tumor bearing mouse (negative control). G. Positive HNA staining of 5 µm paraffin-embedded sections of a human MCF-7 xenograft (positive control). 200× magnification in all panels.