Interaction between multiple myeloma cells and the niche in an <i>in vivo</i> human myeloma model.

<p><b>A.</b> Study design of the NOG-hMM model. Two million EGFP⁺ U266 myeloma (U266-EGFP) cells were intravenously inoculated into 2.4 Gy irradiated NOG (NOD/SCID/g_c^null) mice. Two to six weeks after transplantation, mice were sacrificed for analysis. <b>B.</b> Representative clinical manifestation (upper panel) and radiologic examination (lower panel) of mice 4 weeks after transplantation. All mice showed hind leg paralyses (left) associated with spinal compression fractures (left; arrow). This clinical manifestation was observed in more than 20 mice. <b>C.</b> Representative FACS plot of U266-EGFP cell-transplanted NOG mice. Bone marrow of NOG mice was analyzed by FACS 4 weeks after U266-EGFP cell transplantation using anti-human CD138 antibody and anti-murine CD45 antibody. The experiment was performed in more than forty mice with similar results. <b>D.</b> Serum levels of human IgE. Human IgE levels in the serum of NOG mice at 0 (non-transplanted, non-irradiated mice), 5 or 35 days after transplantation with U266-EGFP cells were analyzed by ELISA (n = 3–5, mean±SD). The experiment was performed twice with similar results. <b>E.</b> Double immunohistochemistry (IHC) of EGFP (green) and TOTO3 (blue) of the BM (upper panels), spleen or liver (lower panels) at 2 weeks after transplantation. U266-EGFP cells engrafted only in the BM. Representative data from 10 to 20 fields from the BM of two mice from three independent experiments are shown. Bars = 200 µm. <b>F.</b> Immunohistochemical (IHC) analysis of EGFP (green) and TOTO3 (blue) at the anatomical region of long bones at the early stage. Representative data from 10 to 20 fields from the BM of two mice from three independent experiments are shown. Bars = 200 µm. <b>G.</b> Quantification of U266-EGFP cells at the diaphysis and the metaphysis of the long bones. U266-EGFP at the metaphysis regions is represented relative to the diaphysis region (diaphysis = 100, n = 3, mean ± SEM). The experiment was performed twice with similar results.