BACKGROUND: Long-term high-dose radiation therapy is important to prevent the recurrence of cancer. But the radioactive rays can also make hurt to the normal tissues. So, researchers focus on the protection of the surrounding normal tissues in the radiotherapy. OBJECTIVE: To study the impact of radiation on the rat masseter muscle and the revasularization ability of the irradiated tissue by vascular endothelial growth factor gene transfection. METHODS: The Wistar rats were radiated by linear accelerator at a dose of 40 Gy. And then the irradiated muscle tissues were transfected with pcDNA4-HisMax-C/vascular endothelial growth factor 165 or empty plasmids. After 2 weeks of gene therapy, transforming growth factor β1 and vascular endothelial growth factor protein were determined using immunohistochemical staining, and the pathological change of the rat masseter muscles was observed under a light microscope. RESULTS AND CONCLUSION: Transforming growth factor β1 protein was highly expressed in the irradiated tissue than the control tissue. Vascular endothelial growth factor protein was significantly increased in the gene transfected group than the radiation group, empty plasmid DNA transfection group and normal control group. These findings indicate that transforming growth factor β1 can improve damaged tissue repair, and vascular endothelial growth factor gene therapy can resume the ability of revasularization of irradiated tissue, thereby promoting irradiated tissue repair.% 背景：放射线对恶性肿瘤的复发起预防作用，但长期大剂量放射治疗会对周围正常组织造成损害，因此如何预防及治疗放射线对周围组织的损伤一直是关注的焦点。目的：观察放射治疗对大鼠咬肌组织的损伤情况及基因转染血管内皮生长因子对咬肌组织血管生成的影响。方法：用直线加速器对 Wistar 大鼠咬肌组织进行照射，总剂量40 Gy ，照射后将重组质粒pcDNA4-HisMax-C/血管内皮生长因子165及空质粒分别转染至大鼠咬肌区。于治疗结束后2周行转化生长因子β1、血管内皮生长因子蛋白免疫组化染色，检测两种蛋白的表达情况，同时在光镜下观察大鼠咬肌组织的病理变化。结果与结论：放疗损伤组大鼠转化生长因子β1的表达水平明显高于正常对照组，重组质粒基因转染后咬肌组织血管内皮生长因子蛋白表达水平明显高于放疗损伤组、空质粒转染组及正常对照组。提示转化生长因子β1可以促进损伤组织的修复；血管内皮生长因子基因转染可促进放射治疗后咬肌组织血管的生成，从而促进放疗损伤的修复。
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