摘要
目的探讨脊柱适形调强放疗(IMRT)和普通放疗对犬脊髓的生物安全性。方法选取纯种比格犬12只并随机分为2组,模拟犬胸9~10椎体肿瘤,以IMRT和普通放疗2种方式分别对2组比格犬胸9~10椎体给予50及70Gy剂量的放疗,于放疗3个月后活杀取材,取相同部位、相同位置的胸9~10节段脊髓行HE染色,电镜观察后,免疫组织化学法定量检测脊髓中Fas、HSP70蛋白的表达,TUNEL法定量检测脊髓中凋亡神经元。结果照射3个月后可观察到脊髓的损伤,IMRT组脊髓神经元以可逆性损伤为主,而普通放疗组以凋亡为主。相同剂量的放疗,IMRT组细胞凋亡指数[50Gy组为(1.2±0.7)%;70Gy组为(2.5±0.8)%]均低于普通放疗[50Gy组为(7.3±1.1)%,70Gy组为(11.3±1.4)%],两组比较差异有统计学意义(50Gy组t=0.022,P〈0.05;70Gy组t=0.017,P〈0.05);凋亡促进蛋白Fas表达量IMRT组(50Gy组为4.6±0.8;70Gy组为7.4±1.1)明显低于普通放疗组(50Gy组为15.1±6.4,70Gy组为19.3±7.6),两组比较差异有统计学意义(50Gy组t=0.231,P〈0.05;70Gy组t=0.457,P〈0.05);而凋亡抑制蛋白HSPT0表达量IMRT组(50Gy组为9.1±0.8,70Gy组为7.3±1.4)明显高于普通放疗组(50Gy组为2.1±0.9,70Gy组为1.7±0.3),两组比较差异有统计学意义(50Gy组t=0.153,P〈0.05;70Gy组t=0.223,P〈0.05)。脊髓神经元凋亡指数与Fas/HSPT0比值呈正相关(r=0.996,t=1.14,P〈0.05)。结论照射3个月后脊髓中存在着明显的放疗迟发反应。通过放疗后脊髓神经元形态学、神经元凋亡指数、凋亡相关蛋白表达等指标的测定结果提示脊柱IMRT的脊髓安全性远优于普通放疗。
Objective To compare the spine intensity modulated radiation therapy (IMRT) and the conventional radiation therapy on the beagle spinal cord neurons, in order to prove the biological safety of IMRT of the spinal cord. Methods Twelve selected purebred beagles were randomly divided into 2 groups. A beagle clinical model of tumor was mimiced in the ninth and tenth thoracic vertebrae. Then the beagles were irradiated by 2 different models of intensity modulated radiotherapy and conventional radiation therapy, with the total irradiation doses of 50 and 70 Gy. The samples of spinal cord were taken out from the same position of the nine and tenth thoracic vertebrae at the third month after radiation. All the samples were observed by the electron microscope, and the Fas and HSP70 expression in spinal cord neurons were evaluated by immunohistochemistry method. Terminal deoxynucleatidyl transferase mediated dUTP nick and labeling (TUNEL) technique was used to examine the apoptotic cells in the spinal cord. Results The neurons in the spinal cord of IMRT group were mainly reversible injury, and those in the conventional radiation therapy were mainly apoptosis. Compared with the conventional radiation therapy group [ 50 Gy group,(7.3±1. 1)% ;70 Gy group, (11.3 ±1.4)%], the apoptosis rate of the spinal cord neurons of the intensity modulated radiotherapy group [ 50 Gy group, ( 1.2 ± 0.7 ) % ;70 Gy group ( 2.5± 0. 8 ) % ] was much lower [(50 Gy group, t = 0.022,P 〈 0.05;70 Gy group, t =0.017,P 〈0.05)]. The expression levels of Fas in the IMPT group(50 Gy group, 4. 6±0. 8;70 Gy group, 7.4±1. 1 ) were also much lower than those in the other group (50 Gy group, 15.1±6. 4;70 Gy group, 19.3±7.6. 50 Gy group, t = 0. 231 ,P 〈 0. 05 ;70 Gy group, t = 0. 457, P 〈 0. 05 ), while the expression levels of HSP70 in the IMPT group(50 Gy group, 9.1 ± 0. 8;70 Gy group, 7.3 ±1.4) were much higher than those in the conventional radiation therapy group(50 Gy group, 2. 1 ±0. 9;70 Gy group, 1.7±0.3; 50 Gy group, t = 0.153,P 〈0.05;70 Gy group, t =0.223,P 〈 0.05). The expression of Fas/HSP70 was positively correlated with the apoptosis rate of the spinal cord neurons (r=0. 996,t = 1.14 ,P 〈0. 05). Conclusions The late radiotherapy response of the spinal cord neurons was obviously observed on the third month. Comparison of the morphology and apoptosis rate of the spinal cord neurons after radiotherapy, the expression of Fas and HSP70 indicated that the biological safety in the IMRT might be much better than that the conventional radiation therapy.
出处
《中华放射医学与防护杂志》
CAS
CSCD
北大核心
2010年第1期15-19,共5页
Chinese Journal of Radiological Medicine and Protection
基金
新疆维吾尔自治区科技攻关(含重大专项)重点项目(200833116)