辐照灭菌对大鼠骨生物力学的影响

Effects of radiation sterilization on the biomechanical properties of Wistar rat’s bone

背景:辐照对骨移植材料生物力学性能的影响及多大灭菌剂量有影响还不明确。目的:探讨不同剂量gamma射线辐照对大鼠骨生物力学的影响及干冰低温和自由基清除剂-硫脲的保护作用。设计、时间及地点:随机同期对照动物体外实验,于2006-12/2008-01在南方医科大学医用生物力学实验室完成。材料:35只2月龄雄性Wistar大鼠。硫脲由天津市科密欧化学试剂开发中心提供。方法:取大鼠股骨剔除所有软组织后,分成7组,每组10根股骨,即:未辐照组、接受15kGy辐照组、接受20kGy辐照组、接受25kGy辐照组、在干冰保护下接受25kGy辐照组、经硫脲处理后接受25kGy辐照组、接受50kGy辐照组。gamma射线照射在华南农业大学^(60)Co辐照中心进行。主要观察指标:辐照后每组取8根股骨进行扭转试验的生物力学测试。结果:15,20kGy辐照组与未辐照组扭转试验的生物力学测试最大转矩、扭角和剪切弹性模量结果相近,差异无显著性意义。接受25,50kGy辐照组抗扭转能力明显低于未辐照组(P<0.05),接受25kGy辐照组抗扭转能力明显高于50kGy辐照组(P<0.05),接受25kGy辐照组抗扭转能力明显低于干冰保护下接受25kGy辐照组和经硫脲处理后接受25kGy辐照组(P<0.05),干冰保护下接受25kGy辐照组和经硫脲处理后接受25kGy辐照组差异无显著性意义(P>0.05)。结论:gamma射线辐照对骨生物力学特性的影响有剂量依赖性,15,20kGy剂量辐照对骨生物力学特性无影响,达到25kGy辐照时开始有一定影响,辐照50kGy时有明显影响;在辐照过程中,干冰低温和自由基清除剂-硫脲对骨生物力学特性具有保护作用。作者认为20kGy是同种异体骨辐照灭菌的适合剂量,在辐照过程加以使用干冰和硫脲有利于对骨生物力学的保护。

BACKGROUND： It is an uncertain issue that the radiation influences the biomechanical properties of bone graft materials and the exact sterling dose. OBJECTIVE： To study the effects of various doses of gamma radiation on the biomechanical properties of rat bone and the protective role of dry ice and thiourea. DESIGN, TIME AND SETTING： A randomized concurrent controlled animal in vitro experiment was performed in the Laboratory of Medical Biomechanics, Southern Medical University between December 2006 and January 2008. MATERIALS： A total of 35 two months male Wistar rats. The thiourea was offered by Tianjin Kermel Chemical Reagent Co. Ltd. METHODS： Wistar rats were killed, and their femurs were cut off with all soft tissues cleared off. According to the conditions of gamma irradiation, 10 femurs served as a group and the experiments were divided into 7 groups： non-irradiated control, irradiated with 15 kGy, irradiated with 20 kGy, irradiated with 25 kGy, irradiated with 25 kGy under dry ice protection, irradiated with 25 kGy after thiourea treatment and irradiated with 50 kGy groups. Gamma radiation was conducted at ^60Co Radiation Center of South China Agricultural University. MAIN OUTCOME MEASURES： Eight femurs in each group were underwent torsion test to evaluate the biomechanical properties. RESULTS： The biomechanical parameters （maximum torsional momentque, torsion angle and shearing elastic modulus） of Wistar rat＇s femur irradiated with 15 and 20 kGy were almost the same with that of control group in torsion test. But only the anti-torsion property in the group of 25 and 50 kGy groups reduced significantly compared with control group（P 〈 0.05）. The parameters in the group of 25 kGy were better than that of 50 kGy but poorer than that of 25 kGy under dry ice protection or irradiated with 25 kGy after thiourea treatment （P 〈 0.05）. No significant difference was observed under dry ice protection and after thiourea treatment （P 〉 0.05）. CONCLUSION： The gamma radiation has dose-dependent effect on the biomechanical properties of Wistar rat＇s bone. The biomechanical properties are not effected by irradiated with 15 or 20 kGy, but reduced by irradiated with 25 kGy and reduced significantly by 50 kGy. Dry ice and thiourea can protect the biomechanical properties of Wistar rat＇s bone from irradiation. 20 kGy is suggested to an ideal dose of irradiation sterilization for allogeneic bone.