Study On Protective Effect Of30mW/cm~2Microwave On X-ray Induced Hematopoietic Damage

Objective:Hematopoietic tissue is both important effector organ of electromagnetic radiation and one of the sensitive tissue of ionizing radiation. Microwave stems from Microwave communication is electromagnetic wave that the frequency range is from300MHZ to300GHZ, it might be a potential method for prevention and treatment of radiation damage. In present study,we investigate the protective effect and mechanism of30mW/cm2microwave on X-ray induced hematopoietic damage,in order to provide theoretical basis and experimental data of microwave protection for ionizing hematopoietic damage. Methods:(1) The effect of30days survival rate with/without microwave and X-ray in mice:mice were randomly divided into5groups:normal control group, microwave alone group(30mW/cm2), X-ray irradiation alone group(7.0Gy X-ray), two combined radiation groups(30mW/cm2+7.0Gy X-ray and7.0Gy X-ray+30mW/cm2), each group consisted of12mice. When mice of each groups were respectively irradiated, mice survival rate, mean survival time and protective factors were determined in order to analyze differences of the micro-wave protective effect for ionizing hematopoietic damage in two combined radiation groups and clear further study on irradiation sequence with microwave and X-ray.(2)To study the protective effect of30mW/cm2microwave on X-ray induced hematopoietic damage in vivo:mice were randomly divided into4 groups:normal control, microwave alone(30mW/cm2), X-ray irradiation alone(5.0GyX-ray), combined irradiation(5.0GyX-ray+30mW/cm2), each group consisted of10mice. The following analyzes were done on day2,7and12: Number counting of peripheral white blood cell and measurement of spleen coefficient; Pathological observations of bone marrow; Colony forming Hemopoietic cells (CFC) assay.(3) To study the protective effect of30mW/cm2microwave on X-ray induced hematopoietic damage in bone marrow stromal cell(BMSCs) in vitro:The lineage differentiation capacity of BMSCs isolated and cultured from mouse compact bone, osteogenic and adipogenic inductions were performed in vitro; Mice groups and irradiation conditions were the same as the study on the protective effect of microwave in mice, MTT assays for proliferation of BMSCs on day1,2,3,4,5and6were done after irradiation.(4) To study the mechanism of protective effect of microwave on X-ray induced hematopoietic damage:Mice groups and irradiation conditions were the same as the study on the protective effect of microwave in mice, qRT-PCR assays for expression of cell cycle related genes Catalase, Notch1on day2,7and12were done after irradiation. Results:(1) Combined radiation (7.0GyX-ray+30mW/cm2) could increase survival rate of X-ray exposed mice from33.3%to66.7%, the mean survival time was16.00±4.32and the protective factor of microwave wasl.51, which was stronger than combined radiation(30mW/cm2+7.0GyX-ray) that survival rate is16.7%and the mean survival time was9.20±2.94(p<0.05).(2) Combined radiation(5.0GyX-ray+30mW/cm2) compared with the X-ray alone group promoted the recovery of the X-ray induced reduction of WBC number and spleen coefficient(p<0.05); pathological bone marrow damages of combined radiation(5.0GyX-ray+30mW/cm2) were less severe; the number of CFC in combined radiation(5.0GyX-ray+30mW/cm2) was up-regulated on day2and12(p<0.05and p<0.01).(3) The multilineage differentiation assays show that BMSCs can readily differentiate into osteoblasts and adipocytes. The proliferation of BMSCs in combined radiation(5.0GyX-ray+30mW/cm2) was greater than that of X-ray alone group(p<0.05å'Œp<0.01).(4) The mRNA expressions of Catalase, Notch1in combined radiation(5.0GyX-ray+30mW/cm2) were significantly increased on2d,7d(p<0.05and p<0.01). Conclusion:(1) Combined radiation (7.0GyX-ray+30mW/cm2) could enhance survival rate of X-rays irradiated animals and prolong their survival time, so which was used to further study.(2)30mW/cm2microwave has a protective effect on hematopoietic injury induced by X-ray ionizing radiation in vivo, and it could reduce BMSCs cell death induced by the X-ray ionizing radiation and promote BMSCs cell proliferation in vitro.(3)30mW/cm2microwave up-regulated expressions of Catalase, Notch1, which might be one of mechanism of its protective effect on X-ray induced hematopoietic damage.