OBJECTIVETo explore effects of iron overload on hematopoiesis in mice with bone marrow injury and its possible mechanism (s).

METHODSC57BL/6 mice were divided into control, iron, irradiation, irradiation+iron groups. The iron-overloaded model of bone marrow injury was set up after mice were exposed to the dose of 4 Gy total body irradiation and (or) were injected iron dextran intraperitoneally. Iron overload was confirmed by observing iron deposits in mice and bone marrow labile iron pool. Additionally, the number of peripheral blood and bone marrow mononuclear cells and the frequency of erythroid cells and myeloid cells were counted and hematopoietic function was assessed.

RESULTS(1)Iron overload occurred by bone marrow biopsy and flow cytometry analysis. (2)Compared with control group, the number of platelets [(801.9±81.2)×10⁹/L vs (926.0±28.2)×10⁹/L] and BMMNC and the frequency of erythroid cells and myeloid cells decreased. Moreover, hematopoietic colony forming units and single-cell cloning counts decreased significantly in irradiation group (P<0.05). (3)Compared with irradiation group, the number of platelets [(619.0±60.9)×10⁹/L vs (801.9±81.2)×10⁹/L] and the frequency of erythroid cells and myeloid cells decreased; moreover, hematopoietic colony forming units and single-cell cloning counts decreased significantly in irradiation+iron group (P<0.05). (4)Compared with irradiation group, ROS level increased by 1.94 fold in BMMNC, 1.93 fold in erythroid cells and 2.70 fold in myeloid cells, respectively (P<0.05).

CONCLUSIONThe dose of 4 Gy total body irradiation caused bone marrow damage and iron overload based on this injury model, which could damage bone marrow hematopoietic function aggravatingly. And further study found that iron overload was closely related to increased ROS level in BMMNC. The findings would be helpful to further study the injury mechanism of iron overload on the hematopoiesis of bone marrow.