内窥镜在模拟人结直肠癌散发性癌灶模型构建及监测中的应用

Application of endoscope in modeling and monitoring of sporadic foci of human colorectal cancer

目的通过构建模拟人结直肠癌散发性癌灶小鼠模型,探讨硬质内窥镜与纤维支气管镜在肿瘤构建及监测中的应用价值。方法 4周龄雄性C57小鼠30只,应用硬质内窥镜行小鼠结直肠黏膜下美蓝注射,通过观察黏膜下隆起情况及退针后美蓝流失情况评价该方法的可行性。APClox P/lox P基因工程鼠100只,随机分为两组各50只,分别采用慢病毒灌肠法(灌肠组)与经硬质内窥镜慢病毒结直肠黏膜下注射法(注射组)构建模拟人结直肠癌散发性癌灶。慢病毒感染后第3周开始,每周末用纤维支气管镜监测肠腔内肿瘤生长情况,同时行小鼠活体成像监测肿瘤发展与转移情况。慢病毒感染后第9周末,两组行安乐死后解剖取材,记录肠腔内肿瘤生长情况,所有标本行组织病理学检查,最后计算两组成瘤率及纤维支气管镜对不同位置、大小肿瘤的检出情况。结果美蓝注射成功率为76.7%。灌肠组成瘤率14%,低于注射组的42%(P<0.05)。100只小鼠中,解剖发现成瘤小鼠28只、瘤块34个,纤维支气管镜检出21只小鼠、瘤块26个(76.5%),其中肿块直径<2 mm以及距离肛门超过2 cm的肿块检出率较低。纤维支气管镜检出肿瘤的位置(距肛外缘距离)、大小与解剖检测结果相关(r分别为0.99、0.97,P均<0.05)。小鼠活体成像检出上述28只均为阳性,检出率为100%。结论经硬质内窥镜行慢病毒结直肠黏膜下注射能提高结直肠癌散发性癌灶小鼠成瘤率,纤维支气管镜可有效监测肠腔内的肿瘤生长情况并在体取材,与小鼠活体成像法相结合能更有效地监测肿瘤发生、发展与转移情况。

Objective To establish a sporadic colorectal cancer model and to study the application of endoscopy and fiber bronchoscope in the modeling and monitoring of tumor. Methods We selected 30 healthy 4-week-old male rats,and methylene blue was injected into the colorectal submucosa by using endoscope. Then we evaluated the effectiveness of this method by observing the submucosal bulge and the leakage of methylene blue after pulling out the needle. APClox P/lox P mice were randomly divided into two groups with 50 in each group. Lentivirus enema was administered intrarectally and injected to colorectal mucosa to establish a sporadic colorectal cancer model. At the 9 th week after lentivirus infection,mice in the two groups were anaerobicly dissected to record the growth of tumors. All specimens were examined histopathologically. Finally,the tumor formation rates were calculated,as well as the examination of tumors with different locations and sizes by using fiber bronchoscope. Results The success rate of methylene blue injection was 76. 7%. The tumor formation rate of enema group was 14%,which was lower than that of the injection group（ 42%）（ P〈0. 05）. In 100 mice,28 mice with 34 tumors were detected. Moreover,21 mice were tumorigenic with 26 lumps（ 76. 5%）,which were detected by fiberoptic bronchoscopy. The detection rate was low when the diameter of the tumor was less than 2 mm or more than 2 cm away from the anus. The position of the tumor（ distance from the anus rim） and the size of the tumor were detected by fiberoptic bronchoscopy and were linearly correlated with the results of the anatomic examination（ P〈0. 05）. Twenty-eight mice were positive by in vivo imaging,and the detection rate was 100%. Conclusion Endoscopic injection of lentivirus into colorectal mucosa can increase the tumor formation rate. The development of colorectal cancer can be more effectively monitored by fiberbronchoscope especially in combination with in vivo imaging.