Establishment of human acute monocytic leukemia model with systemic infiltration in NPG mice.

A model construction of systemic acute leukemia is challenging. Herein, we established a systemic leukemia mouse model using highly immunodeficient NPG mice without any immunosuppressive treatments. NPG mice received tail intravenous injection of SHI-1 cells at the concentration of 1×107 cells (group A) or 5×107 cells (group B) and randomly sacrificed each seven days post-inoculation. Tumor development was monitored using nested-PCR, peripheral blood-smear analysis, flow cytometry, pathological examinations, and immunohistochemistry. The median survival of mice in groups A and B were 33.0 and 30.0 days, respectively. Blast cells in peripheral blood appeared on day 14 in group B, and on day 21 in group A. In addition, SHI-1 cell specific MLL-AF6 mRNA was detected in both spleen and bone marrow on day 14 post-inoculation. 21 days after inoculation, we observed human CD45+CD33+ cells with an SH-1-immunophenotype in the peripheral blood, spleen, and bone marrow, as well as solid neoplasms in multiple organs. Moreover, the histologically infiltrated leukemic cells expressed CD45. In conclusion, the current study demonstrated the normal growth of SHI-1 cells in the NPG mice without immunosuppression, which caused systemic leukemia similar to that observed in acute leukemia patients. We developed an efficient and reproducible model to study leukemia pathogenesis and progression.