In vivo tumor targeting and imaging with anti-vascular endothelial growth factor antibody-conjugated dextran-coated iron oxide nanoparticles

Abstract

Background

Active targeting by specific antibodies combined with nanoparticles is a promising technology for cancer imaging and detection by magnetic resonance imaging (MRI). The aim of the present study is to investigate whether the systemic delivery of antivascular endothelial growth factor antibodies conjugating to the surface of functionalized supermagnetic iron oxide nanoparticles (anti-VEGF-NPs) led to target-specific accumulation in the tumor.

Methods

The VEGF expression in human colon cancer and in Balb/c mice bearing colon cancers was examined by immunohistochemistry. The distribution of these anti-VEGF-NPs particles or NPs particles were evaluated by MRI at days 1, 2, or 9 after the injection into the jugular vein of Balb/c mice bearing colon cancers. Tumor and normal tissues (liver, spleen, lung, and kidney) were collected and were examined by Prussian blue staining to determine the presence and distribution of NPs in the tissue sections.

Results

VEGF is highly expressed in human and mouse colon cancer tissues. MRI showed significant changes in the T*₂ signal and T₂ relaxation in the anti-VEGF-NP- injected-mice, but not in mice injected with NP alone. Examination of paraffin sections of tumor tissues stained for the iron constituent of the NPs with Prussian blue revealed a strong blue reaction in the tumors of anti-VEGF-NP-treated mice, but only a weak reaction in mice injected with NPs. In both groups, at all time points, Prussian blue-stained liver and spleen sections showed only light staining, while stained cells were rarely detected in kidney and lung sections. Transmission electron microscopy showed that many more electron-dense particles were present in endothelial cells, tumor cells, and extracellular matrix in tumor tissues in mice injected with anti-VEGF-NPs than in NP-injected mice.

Conclusion

These results demonstrated in vivo tumor targeting and efficient accumulation of anti-VEGF-NPs in tumor tissues after systemic delivery in a colon cancer model, showing that anti-VEGF-NPs have potential for use as a molecular-targeted tumor imaging agent in vivo.

Keywords:

• nanoparticles
• vascular endothelial growth factor
• colon tumor
• magnetic resonance imaging
• transmission electron microscopy

Acknowledgments

The first two authors contributed equally to this study. This work was supported by research grants from the National Science Council (NSC-99-2320-B-002-022-MY3 and NSC- 96-2314-B-002-150-MY3), the National Taiwan University Hospital (NTUH-099-001310 and NTUH-100-001662), and the Chi-Hua Educational Foundation (QH-2011-001). The MRI studies were supported by the Department of Nuclear Medicine, NTUH and the Small Animal PET/CT Core Facility of Neurobiology and Cognitive Science Center, National Taiwan University.

Disclosure

The authors report no conflicts of interest in this work.