The severe combined immunodeficient (SCID) mice which lack the functional T and B lymphocytes have been widely used for the research of various human diseases including AIDS, transplantation, autoimmune disease and cancer. The purpose of this study was to evaluate the huPBMC-SCID mouse as an animal model for human breast cancer research.

5×10⁷ human PBMC (peripheral blood mononuclear cell) were injected intraperitoneally in 18 SCID mice. After 24 hours, 2.5×10⁶, 5×10⁶ and 10×10⁶ MCF-7 human breast cancer cells were innoculated subcutaneously in the right flank of each of the 3 groups of 6 huPBMC-SCID mice.

4 subcutaneous ecchymosis (2 perioral area, 2 scalp), 1 splenomegaly and 1 hepatic embolism were found during the 20 weeks after the injections. The growth of tumor xenograft was identified in 14 of the total 18 huPBMC-SCID mice, and the growth rate of the tumor was proportional to the number of the innoculated cancer cells. Distant metastases were found in the retroperitoneum, kidney, pelvic cavity, omentum, perisplenic area and regional lymph node in 50% of mice, but not in the lung and liver at 20 weeks.

In summary, the huPBMC-SCID mouse was expected to play an important roles as an animal model of human cancers including breast cancer.