Ultrasound Molecular Imaging of Angiogenesis Using Vascular Endothelial Growth Factor-Conjugated Microbubbles

Abstract

Imaging of angiogenesis receptors could provide a sensitive and clinically useful method for detecting neovascularization such as occurs in malignant tumors, and responses to anti-angiogenic therapies for such tumors. We tested the hypothesis that microbubbles (MB) tagged with human VEGF121 (MBVEGF) bind to the kinase insert domain receptor (KDR) in vitro and angiogenic endothelium in vivo, and that this specific binding can be imaged on a clinical ultrasound system. In this work, targeted adhesion of MBVEGF was evaluated in vitro using a parallel plate flow system containing adsorbed recombinant human KDR. There was more adhesion of MBVEGF to KDR-coated plates when the amount of VEGF121 on each MB or KDR density on the plate was increased. MBVEGF adhesion to KDR-coated plates decreased with increasing wall shear rate. On intravital microscopic imaging of bFGF-stimulated rat cremaster muscle, there was greater microvascular adhesion of MBVEGF compared to that of isotype IgG-conjugated control MB (MBCTL). To determine if MBVEGF could be used to ultrasonically image angiogenesis, ultrasound imaging was performed in mice bearing squamous cell carcinoma after intravenous injection of MBVEGF. Ultrasound videointensity enhancement in tumor was significantly higher for MBVEGF (17.3±9.7 dB) compared to MBCTL (3.8±4.4 dB, n=6, p<0.05). This work demonstrates the feasibility of targeted ultrasound imaging of an angiogenic marker using MBVEGF. This approach offers a non-invasive bedside method for detecting tumor angiogenesis and could be extended to other applications such as molecular monitoring of therapeutic angiogenesis or anti-angiogenic therapies in cardiovascular disease or cancer.

Clinical value and application of contrast-enhanced ultrasound in the differential diagnosis of malignant and benign breast lesions

“…The new-generation contrast agent SonoVue is able to clearly visualize the microcirculation of the breast lesion (14), making true microcirculation imaging possible (15). Microcirculation imaging, performed as an additional round of imaging following the conventional ultrasound, is able to reflect the blood flow perfusion of normally structured and tumor tissue (16), under color Doppler and energy Doppler flow imaging. To date, clinical studies have indicated that application of contrast agents significantly improves the diagnostic accuracy for breast lesions.…”

Bevacizumab and near infrared probe conjugated iron oxide nanoparticles for vascular endothelial growth factor targeted MR and optical imaging

“…VEGF targeted molecular imaging probe and image-guided delivery of anti-VEGF agents thus may enable the precision medicine and improve survival of cancer patients. 14–16 Several earlier attempts have explored the feasibility of using VEGF as a biomarker for molecular imaging using ultrasound, 17 X-ray computered tomograph (CT), 18 nuclear imaging, 19 optical imaging 20 as well as magnetic resonance imaging (MRI), 21 but the integration of multiple modalities for VEGF-targeted imaging, which can improve the accuracy of targeted imaging and the range of image-guided intervention, such as pre- and intra-operative imaging, has only received limited investigation. 22–24…”

Efficient targeted tumor imaging and secreted endostatin gene delivery by anti-CD105 immunoliposomes

“…Furthermore, when combined with tumor-specific markers, the efficiency of targeted delivery can be significantly enhanced [ 11 , 13 ]. Nanographenes synthesized to target CD105 with anti-CD105 mAb or microbubbles conjugated with anti-vascular endothelial growth factor (VEGF) mAb have been reported to be specifically directed to tumor microvasculature in vivo [ 15 , 16 ]. The significantly improved tumor targeting efficiency of a transferrin-conjugated Lp system described in our previous work [ 13 ] may be utilized for tumor neovasculature-targeted imaging and/or therapeutic gene delivery in vivo.…”