Background & objective: Acute leukemia is always accompanied by extramedullary infiltration, which may be the source of relapse. The mechanism of infiltration is unclear yet. This study was to establish a leukemic extramedullary infiltration model for exploring the mechanism.
Methods: After being treated by splenectomy, cytoxan intraperitoneal injection, and sublethal irradiation, 4-and 6-week old BALB/c nu/nu mice were transplanted intravenously with 5x10(6) or 1x10(7) of SHI-1 human monocytic leukemic cells. The leukemic cells engrafted into the mice were tracked by reverse transcription-polymerase chain reaction (RT-PCR), histopathologic examination, immunohistochemistry, and flow cytometry (FCM).
Results: SHI-1 cells were engrafted in nude mice and infiltrated into the stomach, liver, lungs, brain, kidneys, bone marrow, and so on, and formed green solid tumors in some positions. Autopsy revealed that neoplasms were found in more organs in 4-week old mice than in 6-week old mice. Human CD45-positive cells were detected in the bone marrow of 4-week old mice but not in 6-week old mice.
Conclusion: SHI-1 cells can be engrafted in the pretreated nu/nu mice, and this model provides a useful experimental system for the research of leukemic extramedullary infiltration.