大鼠半胸照射致肺纤维化模型的病理学观察

Pathologic observation of irradiation-induced pulmonary fibrosis in rats with a single dose irradiation to right hemithorax

目的观察辐射致鼠肺纤维化病变发生过程的病理特征及其规律。方法35只雄性SD大鼠分为实验组21只和对照组14只。实验组用8MV直线加速器给予大鼠右半胸20Gy单次照射,对照组佯装照射。在照射后1、3、7、14、28、84、164d共7个时相点,分批活杀大鼠(照射组3只,对照组2只),观察其全肺大体形态改变,取右肺中叶组织进行光镜及电镜病理组织形态观察。结果照射后1、3、7d可见肺实质细胞的损伤,内皮细胞核损伤出现最早;照射后14、28d肺泡间隔渐加宽,并有胶原和成纤维细胞的增生;照射后84、164d出现典型的肺纤维化病灶,肺实变区域有新生的血管内皮细胞和较多的肺泡Ⅱ型上皮细胞,肺泡腔内可见大量吞噬细胞。结论血管内皮细胞可能为辐射损伤最敏感的肺实质细胞。

Objective To observe the pathologic features and regularity of the irradiation-induced rat pulmonary fibrosis. Methods Thirty-five adult male Sprague Dawley rats were divided into 7 groups randomly. In every group 3 rats were irradiated with a single dose of 20 Gy to their fight hemithoraxes with an 8 MV linear accelerator and 2 rats were received sham irradiation. On day 1,3,7, 14, 28, 84,or 164 after radiation, all animals were sacrificed and the total lungs were harvested for macrography and all middle lobes of the right lungs were resected as the specimens for light and electronic microscope examination. Results Pulmonary parenchyma cells in the irradiated rats showed damaging changes as compared with sham rats on day 1, 3, and 7 afterradiation, and the endothelial injury was ahead of other parenchyma cells. On day 14 and 28 after-irradiation, the major pathological changes of the irradiated lungs consisted of thickening and edema of the alveolar septum as well as the hyperplasia of collagen and fibroblasts. Typical fibrosis focus, renascent endothelium cells and more type Ⅱ pneumocyte, and a large number of phagocytes in alveolar lumen were seen in irradiated lung specimens on day 84 and 168 after-irradiation. Conclusion Endothelial cells may have the most sensitivity to irradiation in all of pulmonary parenchyma cells.