RGD-Targeted Ultrasound Contrast Agent for Longitudinal Assessment of Hep-2 Tumor Angiogenesis In Vivo |
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Authors: | Qiao Hu Xiao-Yan Wang Li-Ke Kang Hai-Ming Wei Chun-Mei Xu Tao Wang Zong-Hua Wen |
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Institution: | 1. Department of Diagnostic Ultrasound, the People’s Hospital of Guangxi Zhuang Autonomous Region, Nanning, China;2. Department of Pathology, the People’s Hospital of Guangxi Zhuang Autonomous Region, Nanning, China;3. Department of Otolaryngology-Head & Neck Surgery, the People’s Hospital of Guangxi Zhuang Autonomous Region, Nanning, China;IDI, Istituto Dermopatico dell''Immacolata, ITALY |
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Abstract: | ObjectiveTo prepare arginine-glycine-aspartate (RGD)-targeted ultrasound contrast microbubbles (MBs) and explore the feasibility of their use in assessing dynamic changes in αvβ3 integrin expression in a murine model of tumor angiogenesis.MethodsRGD peptides were conjugated to the surfaces of microbubbles via biotin-avidin linkage. Microbubbles bearing RADfK peptides were prepared as controls. The RGD-MBs were characterized using an Accusizer 780 and optical microscopy. The binding specificity of the RGD-MBs for ανβ3-expressing endothelial cells (bEnd.3) was demonstrated in vitro by a competitive inhibition experiment. In an in vivo study, mice bearing tumors of three different stages were intravenously injected with RGD-MBs and subjected to targeted, contrast-enhanced, high-frequency ultrasound. Subsequently, tumors were harvested and sectioned for immunofluorescence analysis of ανβ3 expression.ResultsThe mean size of the RGD-MBs was 2.36 ± 1.7 μm. The RGD-MBs showed significantly higher adhesion levels to bEnd.3 cells compared to control MBs (P < 0.01). There was rarely binding of RGD-MBs to αvβ3-negative MCF-7 cells. Adhesion of the RGD-MBs to the bEnd.3 cells was significantly inhibited following treatment with anti-alpha(v) antibodies. The quantitative acoustic video intensity for high-frequency, contrast-enhanced ultrasound imaging of subcutaneous human laryngeal carcinoma (Hep-2) tumor xenografts was significantly higher in small tumors (19.89 ± 2.49) than in medium tumors (11.25 ± 2.23) and large tumors (3.38 ± 0.67) (P < 0.01).ConclusionsRGD-MBs enable noninvasive in vivo visualization of changes in tumor angiogenesis during tumor growth in subcutaneous cancer xenografts. |
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