中子和γ射线照射对小鼠骨髓造血细胞死亡方式的探讨

Death modes of hematopoietic cells in neutron and gamma-ray irradiated mouse bone marrow

目的 探讨中子和γ射线照射后小鼠骨髓造血细胞的死亡方式及其意义。方法 采用不同剂量中子和6 0 Coγ射线全身照射 35 0只BALB/c小鼠 ,通过光镜、电镜、流式细胞术、原位末端标记和DNA凝胶电泳等观察造血细胞凋亡与坏死情况。结果 中子照射后小鼠骨髓中坏死和凋亡的造血细胞均明显增多 ,5 5Gy组以坏死为主 ;而γ射线照射后则以凋亡为主 ,且呈剂量相关性。凋亡的细胞表现为核染色质浓缩、边移 ,呈半月型、环状或不规则状 ,凋亡小体形成 ,电泳下见DNA梯状图谱。坏死的细胞表现为核肿胀、溶解 ,线粒体膜、核膜等膜性结构破坏。结论 2 5～ 5 5Gy中子及 5 5～ 12Gyγ射线照射可使骨髓造血细胞死亡方式不同 :中子照射见凋亡与坏死并存 ,5 5Gy组以坏死为主 ;而γ射线照射则以凋亡为主。

Objective To investigate the death modes of hematopoietic cells in neutron and γ-ray irradiated mouse bone marrow. Methods 350 BALB/c mice were total body irradiated with various doses of neutron and γ rays,sacrificed separately at 6 and 12 hours,1,2,3,4,5,7,10,14,21 and 28 days after radiation.By means of light microscopy,electron microscopy,flow cytometry, in situ terminal end labeling and DNA gel electrophoresis,the apoptosis and necrosis of hematopoietic cells were studied. Results The hematopoietic cells undergoing apoptosis and necrosis were obviously increased after neutron irradiation,and necrosis was the main death mode in dose of 5.5 Gy.Meanwhile,γ irradiation mainly induced apoptosis of hematopoietic cells,and the changes were correlated with the radiation dose.The apoptosis was characterized by chromatin concentration and margination,in half-moon,loop,and irregular shapes,and apoptotic body formation,and DNA ladder formation by gel electrophoresis.The necrosis was manifested as swelling,and lysis of nuclei,and disorganization of membranes of mitochondria and nuclei. Conclusion There are different death modes of hematopoietic cells in neutron and γ-ray-irradiated mouse bone marrow.Neutron induces apoptosis and necrosis of hematopoietic cells while γ-rays mainly induce apoptosis;the main cell death mode in 5.5 Gy dose group is necrosis.