靶向血管内皮生长因子受体2微泡造影剂评价肿瘤血管生成的实验研究

Molecular ultrasound imaging with vascular endothelial growth factor receptor 2-targeted microbubbles in a mouse liver cancer model

目的:探讨靶向血管内皮生长因子受体2(vascular endothelial growth factor receptor 2,VEGFR2)微泡造影剂用于肿瘤血管生成的超声分子成像。方法:用生物素-亲和素桥接法制备靶向VEGFR2超声微泡,免疫荧光法检测微泡与抗体的结合。建立裸鼠Hep G2肝癌皮下种植瘤模型,随机分成靶向组(n=5)和非靶向组(n=5),经尾静脉团注相同剂量靶向微泡或非靶向微泡,录像并绘制时间-强度曲线(time-intensity curve,TIC);注入造影剂5 min后利用高声压爆破技术清除肿瘤内部微泡,比较爆破前后两组造影图像灰阶强度的下降,估计靶向微泡在体内与靶点的结合能力。结果:靶向造影剂和非靶向造影剂均表现为裸鼠皮下瘤的显著增强,但TIC显示两组间曲线下面积差异有统计学意义[(3 940.4±200.9)dB·s vs.(2 796.8±452.3)dB·s,P=0.001];微泡爆破后靶向组灰阶强度降低显著大于非靶向组[(7.61±2.20)dB vs.(3.74±1.40)dB,P=0.010]。结论:靶向VEGFR2微泡造影剂在体内能显著增强肿瘤血管成像,可作为监测肿瘤血管生成的较可靠分子影像学探针。

Objective:To evaluate the feasibility and reproducibility of molecular ultrasound imaging of tumor angiogenesis with vascular endothelial growth factor receptor 2 (VEGFR2)-targeted microbubbles.Methods:VEGFR2-targeted microbubbles were accomplished by anti-VEGFR2 monoclonal antibody conjugation to the microbubble surface using biotin-avidin linkage, which was assessedex vivo using immunolfuorescence. Ten mice bearing subcutaneous human liver tumor were divided into two groups randomly (targeted group,n=5; non-targeted group,n=5) and scanned at 2 weeks after implantation with contrast-enhanced ultrasound (CEUS) using either targeted or non-targeted microbubbles. Following CEUS, time-intensity curves were constructed off-line and perfusion parameters were calculated. The residual bubble signal was determined 5 min after contrast agent injection with destruction-replenishment analysis.Results:Both targeted and non-targeted microbubbles revealed signiifcant enhancementin vivo. A signiifcant difference in area under the curve (AUC) was recorded between targeted group and non-targeted group ((3 940.4±200.9) dB?svs. (2 796.8±452.3) dB?s,P=0.001)After the destruction sequence, there was a signiifcant difference in the decrease of video intensity between targeted group and non-targeted group [(7.61±2.20) dBvs. (3.74±1.40) dB,P=0.010].Conclusion:Molecular ultrasound imaging with VEGFR2-targeted microbubbles is noninvasive, feasible and reproducible to assess tumor angiogenesis.