In Vivo Murine Model of Leukemia Cell-Induced Spinal Bone Destruction

Figure 2

Constitutively active STAT5 signaling induces spine bone destruction by extramedullary invasion of myeloid leukemia cells in vivo. The HL-60 leukemia cells with control or CA-STAT5 overexpression were injected into the NOD/SCID recipient mice irradiated with 1 Gy using the tail vein method. (a) Two or three weeks after transplantation, the PWBCs were counted by flow cytometry. (b) Statistical analysis of mice with paralysis of both legs. value was computed by the chi-square test. (c) Representative images of H&E stained sections of the lumbar spines from the CA-STAT5 mice from low (A) to high (B) magnification. In (c) (A), the red arrow indicates the vertebral body, the black arrow the intervertebral disc, the green arrow the lamina joint, the red triangular region the spinal cord, and the yellow triangular region the leukemic cells. In (c) (B), leukemic cells, unlike normal bone marrow cells, showed irregular shapes, large nuclei, and shallow staining. The yellow arrow indicates the leukemic cells, and the black arrow indicates normal bone marrow cells. (d) Relative invasive tumor area was measured by spinal histomorphometry using H&E stained sections taken at least 25 microns apart. (E) TRAP cytochemical analysis of the representative sections of the lumbar spines from the CA-STAT5 mice (A, B) and control (C, D) from low to high magnification. Invasion of leukemic cells into the spinal bone environment enhanced significantly osteoclast activity (). Deeper red staining represents higher activity. TRAP staining showed no osteoclast activation in the control group. The yellow arrow indicates focal accumulation of leukemic cells, and the black arrow indicates normal bone marrow cells. (f) The osteoclast measurement was performed on multiple TRAP stained sections taken at least 25 microns apart. The data was pooled to generate the derived data. , , compared to the control.

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