兔VX2脑瘤的模型建立及病理学、影像学初步研究

Tumor angiogenesis in rabbit VX2 brain tumor: model establishment,pathologic study and preliminary imaging observation

目的建立稳定的实验性兔VX2脑瘤种植模型并研究其病理学和影像学特性,重点观察肿瘤血管生成情况.方法新西兰大白兔30只,采用无菌手术颅骨钻孔法注射VX2肿瘤细胞悬液(107/ml).行MR检查观察肿瘤生长情况,病理学观察肿瘤大小、形态及组织学改变,免疫组织化学观察血管内皮生长因子(vascular endothelial growth factor, VEGF)表达及微血管密度(microvessel density, MVD).结果 22只实验兔纳入研究,20只成瘤,成瘤率90.9%,MRI可清晰显示肿瘤生长情况,病理学符合鳞癌特点.肿瘤100%有VEGF表达,平均阳性细胞染色率(52.51±19.15)%(19.5%～92.9%).平均MVD(51.30±14.42)条/高倍镜视野(25～81条/高倍镜视野).肿瘤生长时间与体积(r=0.791, P=0.000),MVD与肿瘤生长时间(r=0.875, P=0.000)及体积(r=0.901, P=0.000)均呈正相关.VEGF等级与肿瘤蓝染程度呈正相关(rs=0.594, P=0.015).VEGF等级与MVD(rs=0.404, P=0.087)、肿瘤生长时间(rs=0.350, P=0.142)及体积(rs=0.359,P=0.132)的相关性无统计学意义.结论 采用颅骨钻孔法进行兔VX2脑瘤种植,简便易行,模型稳定,成瘤率高.该模型具有较高的血管生成活性,对实验性肿瘤血管生成的病理学及影像学研究具有重要意义.

Objective To establish a stable implanted model of VX2 rabbit brain tumor, and to evaluate the pathological and imaging features and tumor angiogenesis. Methods Thirty New Zealand white rabbits were implanted with 100 μl viable VX2 tumor cells (107/ml) through a hole 5 mm to the right of the sagittal suture and 5 mm posterior to the coronal suture bored by a dental drill. MRI was performed every ~2 days after 7 days of implantation to evaluate the growth of the tumor, and perfusion CT studies were performed in different days of tumor growth. After that the animals were sacrificed on days 14, 18, 22, 26, and 30 of tumor implantation. 2% Evans blue (2 ml/kg) was given intravenously in 16 of these animals ~1 hour prior to sacrifice to detect the breakdown of the blood-brain barrier (BBB). The specimens of the rabbit brains were examined pathologically and histologically. VEGF and MVD were evaluated in immunohistochemical examination. Results Of the 22 animals included into the study, the tumor grew in 20 animals, which could be seen clearly on MR imaging. Pathologic examination showed characteristics of squamous carcinoma. VEGF was expressed in all tumors with the mean rate of positive cells of (52.51±19.15)% (19.5%-92.9%). Mean MVD was (51.30±14.42)pice piece/microscope (25-81 pice piece/microscope). Using Pearson′s linear correlation analysis, positive correlation was found between tumor growth time and volume (r=0.791, P=0.000), between MVD and tumor growth time (r=0.875, P=0.000), and between MVD and tumor volume (r=0.901, P=0.000), respectively. Spearman′s rank correlation analysis showed positive correlation between VEGF grade and blue stain of the tumor (r_s=0.594, P=0.015). Conclusion A stable model of VX2 rabbit brain tumor has been established with the method of skull drilling. The method was simple and easy to use, with a high tumor growth rate and remarkable angiogenesis. The model is helpful for the pathological and radiological study of tumor angiogenesis.