原核pprI基因活体转染对BALB/c小鼠急性放射损伤保护作用的研究

Role of prokaryotic pprI gene in protecting BALB/c mice from acute radiation injury

目的 研究耐辐射奇球菌pprI基因活体转染对小鼠急性放射损伤的防护作用.方法 采用SPF级纯品系BALB/c雄性小鼠,应用活体电转染技术,将pEGFP-c1空载质粒及pEGFP-c1-pprI基因重组质粒转入小鼠股前肌肉.应用60Coγ射线进行全身照射,死亡率观察组吸收剂量为6 Gy,观察照后30 d内小鼠死亡率的变化;放射效应观察组吸收剂量为4 Gy,于照后1、7、14、28和35 d观察小鼠外周血象、胸腺、脾脏和骨髓细胞的凋亡率,并于照后第7和28天观察小鼠肺脏和睾丸组织的病理变化.结果 质粒注射剂量为50 μg/50μl,电场强度为200 V/cm时转染肌细胞的效率最高.pEGFP-c1-pprI基因重组质粒转染组小鼠急性辐射死亡率为30％,显著低于单纯照射组（60.0％）和空载体组（63.3％）（x2=4.90、6.24,P＜0.05）.与单纯照射组、空载体组比较,pEGFP-c1-pprI基因重组质粒转染组小鼠的外周血白细胞计数在照后1、7、14和28 d显著增高（F=16.26、8.10、6.37、10.74,P＜0.05）,血小板计数在照后第7和14天显著增高（F=7.36、5.71,P＜0.05）,淋巴细胞百分率在照后7d显著增高（F=18.43,P＜0.05）;胸腺和骨髓细胞凋亡率均在照后第1、7、14、28和35天显著降低（F=3.88、14.91、14.14、39.86、5.65,P＜0.05;F=53.70、11.75、21.78、41.40、4.54,P＜0.05）;脾脏细胞凋亡率在照后第1、7、14和28天显著降低（F=97.95、56.61、33.55、14.71,P＜0.05）.pEGFP-c1-pprI基因重组质粒转染组小鼠肺脏和睾丸的放射病理损伤较轻并且恢复较快.结论 耐辐射奇球菌pprI基因活体电转染对BALB/c小鼠急性放射损伤具有显著的保护作用,为进一步临床应用奠定了实验基础.

Objective To investigate the radioresistant effects of pprI gene of Deinococcus radiodurans on BALB/c mice.Methods Male BALB/c mice in SPF level were applied for this work.The pEGFP-c1 plasmid and pEGFP-c1-pprI gene recombinant plasmid were transferred into anterolateral muscle of mice with in vivo electroporation technology.The mice were irradiated by 6 Gy 60Co γ-rays in whole body and the mortality of mice was observed within 30 days after irradiation.In addition,the mouse were irradiated with 4 Gy γ-rays and then the peripheral blood cell number,apoptosis rates of thymocyte cells,spleen cells and bone marrow cells were observed in the days of 1,7,14,28 and 35 after irradiation while the histopathological changes of lung and testis were observed in the days 7 and 28 after γ-ray irradiation.Results The highest gene transfection efficiency of muscle cells was obtained in a Plasmid injection amount of 50 μg/50 μl and electric field strength of 200 V/cm.The acute radiation mortality of pEGFP-c1-pprI gene recombinant plasmid transfer group was 30%,lower than that of irradiation group （60.0%） and pEGFP-c1 plasmid transfer group （63.3%） after 6 Gy γ-ray irradiation （x2 =4.90,6.24,P 〈 0.05）.Compared with the irradiation group and pEGFP-c1 plasmid transfer group,the WBC count of pEGFP-c1-pprI gene recombinant plasmid group in peripheral blood of mice was significantly higher in the days of 1,7,14 and 28 （F =16.26,8.10,6.37,10.74,P 〈0.05）,PLT count was significantly higher in days of 7 and 14 （F =7.36,5.71,P 〈 0.05）,meanwhile the lymphocyte percentage was increased significantly on the 7th day （F =18.43,P 〈 0.05） after irradiation.On the other hand,the apoptosis rates of thymocyte cells and bone marrow cells were significantly decreased in the days of 1,7,14,28 and 35 （F =3.88,14.91,14.14,39.86,5.65,P 〈0.05 and F=53.70,11.75,21.78,41.40,4.54,P 〈0.05） while the apoptosis rate of spleen cells was significantly decreased in the days of 1,7,14 and 28 （F =97.95,56.61,33.55,14.71,P 〈0.05） after irradiation.Finally,the radiation histopathological changes of lung and testis of the pEGFP-c1-pprI gene recombinant plasmid group were slight and easy to recover.Conclusions Transfection of pprI gene of Deinococcus radiodurans by in vivo electroporation has significant protective effect on the acute radiation injury in BALB/c mice,which may have important clinical applications.