目的：通过荧光靶向成像检测血管内皮生长因子(VEGF)在放射性视网膜病变(RR)中的分布表达。

方法：将荧光素FITC与VEGF抗体ranibizumab共价结合，制备靶向荧光成像探针ranibizumab-FITC。SD大鼠按体重均衡原则随机分为3组：正常对照组(Con组)、低剂量放射组(10 Gy组)、高剂量放射组(30 Gy组)，采用医用直线加速器及铅块遮挡对大鼠眼球进行局部照射造模。通过Western blot及qRT-PCR检测各组VEGF-A表达水平，筛选合适的造模剂量。使用倒置荧光显微镜与共聚焦显微镜观察VEGF与成像探针在对照组与RR模型组大鼠视网膜上的分布，验证靶向探针的有效性。

结果：高剂量放射组(30 Gy组)大鼠视网膜VEGF-A表达水平相较正常对照组(Con组)升高，在早期RR中观察到VEGF表达与微动脉瘤和视网膜内微血管异常，毛细血管壁损伤部位存在VEGF积累，当视网膜毛细血管内皮损伤发生时，靶向探针在血管壁外表面聚集。

结论：RR模型大鼠视网膜VEGF表达水平升高，荧光靶向分子成像探针能够检测VEGF在RR大鼠视网膜微血管病变处的空间分布。

METHODS:Covalent binding of fluorescein FITC with VEGF antibody ranibizumab to prepare targeted fluorescent imaging probe ranibizumab-FITC. SD rats were randomly divided into three groups based on the principle of weight balance: a normal control group(Con group), a low-dose radiation group(10 Gy group), and a high-dose radiation group(30 Gy group). Medical linear accelerators and lead blocks were used to locally irradiate the rat eyeballs for modeling. Western blot and qRT-PCR were used to detect the expression levels of VEGF-A in each group and to screen for appropriate modeling dose. The inverted fluorescence microscope and the confocal microscope were used to observe the distribution of VEGF and imaging probes in the retinas of control and RR model group rats, and to verify the effectiveness of targeted probes.

RESULTS:The expression level of VEGF-A in the retina of rats in the high-dose radiation group(30 Gy group)was higher than that in the normal control group(Con group). In early RR, VEGF expression was observed to be associated with microaneurysms and abnormal microvessels in the retina. VEGF accumulation was observed at the site of capillary wall damage. When retinal capillary endothelial damage occurred, targeted probes gathered on the outer surface of the vessel wall.

CONCLUSION:The expression level of VEGF in the retina of RR model rats is elevated, and fluorescent targeted molecular imaging probes can detect the spatial distribution of VEGF at the microvascular lesions in the retina of RR rats.