Mouse model of MM and in vivo experiments

The spontaneous syngeneic immunocompetent mouse model of MM, C57BL/KaLwRij mice⁴⁷, was purchased from Harlan Laboratories Inc. (Harlan Mice, Netherlands), and the mice were housed under conditions approved by the Ethical Committee for Animal Experiments of Institute of Hematology & Blood Diseases Hospital. Injection of the mouse MM cell line 5TGM1 can accelerate MM development. A total of 1 × 10⁶ 5TGM1 cells suspended in 100 μL of PBS (MM-5TGM1) or the same volume of PBS alone (Con) was injected via tail vein into C57BL/KaLwRij mice. The IgG2b level in the serum and the percentage of 5TGM1 myeloma cells in bone marrow were measured to monitor the tumour burden. Six weeks after tumour cell injection, the mice were euthanized humanely and processed to evaluate erythropoiesis in vivo. Bone marrow was collected and detected by flow cytometry as previously reported⁴⁸.