^(60)Co γ射线局部辐射后小鼠非辐射区域骨髓巨核细胞的变化

Effects of ^(60)Co gamma ray local irradiation on bone marrow megakaryocytes in non-irradiation area of mice

目的:临床局部辐射条件下会造成非辐射区域组织及细胞功能损害,最为突出的是对造血功能的影响。实验建立60Coγ射线左半身辐射动物模型,观察局部电离辐射对其非辐射区域骨髓巨核细胞的影响。方法:实验于2003-10/2005-03在解放军第三军医大学辐照中心和全军复合伤研究所完成。①实验动物:6～8周龄SPF级雄性昆明小鼠180只,随机数字表法分为正常对照组、全身辐射组、左半身辐射组、全身屏蔽辐射组,45只/组。②实验方法:全身辐射组小鼠固定于辐射架内;左半身辐射组小鼠麻醉后固定体位,用铅砖屏蔽右半身;全身屏蔽辐射组小鼠麻醉固定体位,用铅砖屏蔽全身。以60Coγ射线一次性辐射,剂量率68.46cGy/min。正常对照组不作任何干预。③实验评估:辐射后不同时相检测小鼠血清丙二醛含量及超氧化物歧化酶活性变化,计数外周血血小板,检测骨髓巨核祖细胞集落形成单位,观察骨髓组织病理改变及CD41a、CD61的表达。结果:全身辐射组第8天死亡2只,第9天死亡4只,其余各组无脱失。①外周血血小板计数:辐射后第2,7天,左半身辐射组外周血血小板数量显著低于正常对照组(P<0.01),但高于全身辐射组(P<0.01)。②血清丙二醛含量及超氧化物歧化酶活性变化:辐射后第2,9天,左半身辐射组血清丙二醛含量显著高于正常对照组(P<0.01),低于全身辐射组(P<0.01);血清超氧化物歧化酶活性显著低于正常对照组(P<0.01),高于全身辐射组(P<0.01)。③骨髓巨核祖细胞集落形成单位的变化:与正常对照组比较,辐射后6h左半身辐射组非辐射侧的巨核祖细胞集落形成单位显著降低(P<0.01),高于全身辐射组及左半身辐射组(P<0.01)。④骨髓组织病理改变:正常对照组有核细胞比例较高,分布均匀,并见多量散在分布的细胞龛;辐射2d后,左半身辐射组非辐射侧骨髓有核细胞较正常对照组减少,但好于全身辐射组、左半身辐射组。⑤骨髓CD41a及CD61表达的变化:辐射后2d与正常对照组比较,左半身辐射组非辐射侧骨髓CD41a及CD61阳性细胞数和相对荧光强度均显著降低(P<0.01),但高于全身辐射组、左半身辐射组(P<0.01)。结论:局部电离辐射作用后,可导致小鼠非辐射区域骨髓巨核细胞增殖能力降低,血小板减少,产生功能障碍。氧自由基激活可能参与了该损伤过程。

The local irradiation in clinic can induce the functional damage of tissues and cells in the non-irradiated area, especially the hematopoietic function. This study is designed to establish the animal model of left-half-body irradiation exposed to^60Co y-ray, and investigate the effects of local ionizing irradiation on megakaryocyte of bone marrow in non-irradiated area. METHODS： The experiment was conducted in the Irradiation Center of the Third Military Medical University of Chinese PLA and the Institute of Military Combined Wound from October 2003 to March 2005.①A total of 180 male Kunming strain mice of SPF grade and 6-8 weeks old were randomly divided into 4 groups （n=45）： normal control group （NC）, total-body-irradiation group （TBI）, left-half-body-irradiation group （LHBI）, and total-body-shield-irradiation group （TBSI）.②Mice in the NC group received no treatment. Mice in the TBI group were fixed in the irradiated frame. Mice in the LHBI group were anesthetized and fixed with right-side body shielded by lead bricks. Mice in the TBSI group were fixed under anesthesia and shielded completely with lead bricks. Mice were exposed to^^60Coy-my at the dose rate of 68.46 cGy/min.③The contents of superoxide dismutase and malondialdehyde in mouse serum were detected at different phases after irradiation, the number of platelet in the peripheral blood and colony forming unit-megakaryocyte （CFU-MK） in the bone marrow were counted, and the expressions of CD41a and CD61 in bone marrow hematopoietic tissues and histopathological change were also measured. RESULTS： Except 2 mice died on the 8^th day and 4 deaths on the 9^th day in the TBI group after irradiation, there were no withdraws from the study.①At the 2^rd and 7^th days, the number of platelet in the peripheral blood in the LHBI group were significantly lower than the NC group （P 〈 0.01）, but higher than the TBI group （P 〈 0.01）.②At the 2^rd and 9^th days, the contents of serum malondialdehyde in mice of the LHBI group were significantly higher than the NC group （P 〈 0.01）, but lower than the TBI group （P〈0.01）; The activity of superoxide dismutase in mice of the LHBI group was obviously lower than the NC group （P〈 0.01）, but higher than the TBI group （P〈 0.01）.③Six hours after irradiation, the number of CFU-MK in the area of non-irradiation in mice of the LHBI group were significantly lower than the NC group （P 〈 0.01 ）, while it was higher than the TBI group and the irradiated area of the LHBI group （P〈 0.01）.④in NC group, there were a large amount of karyocytes that arranged evenly, and most of them were niche cells; At the 2^rd day after irradiation, the number of karyocytes in the area of non-irradiation in mice of the LHBI group was decreased, but still higher than the TBI group and the irradiated area of the LHBI group.⑤The expressions of CD41a and CD61 in the area of non-irradiation area of bone marrow in mice of the LHBI group were significantly lower than the NC group （P〈 0.01）, whereas higher than the TBI group and the irradiated area of the LHBI group （P 〈 0.01）. CONCLUSION： Local ionizing irradiation can decrease the proliferation of bone marrow megakaryocyte in non-irradiation area of mice, and induce the thrombocytopenia and dysfunction. The activation of reactive oxygen free radicals may participate in the injury.