Magnetic resonance imaging of tumor angiogenesis using dual-targeting RGD10-NGR9 ultrasmall superparamagnetic iron oxide nanoparticles.

OBJECTIVE: Using RGD10-NGR9 dual-targeting superparamagnetic iron oxide nanoparticles to evaluate their potential value in tumor angiogenesis magnetic resonance imaging (MRI) and the biodistribution in vitro and in vivo. MATERIALS AND METHODS: Dual-targeting RGD10-NGR9 ultrasmall superparamagnetic iron oxide (USPIO) nanoparticles were designed and synthesized in our previous study. In vitro, prussian blue staining and phenanthroline colorimetry were conducted to evaluate binding affinity and adsorption of dual-targeting USPIO nanoparticles to αvß3-integrin/APN positive cells. In vivo, a xenograft mouse tumor model was used to evaluate the potential of the dual-targeting nanoparticles as an MRI contrast agent. After intravenous injection, the contrast-to-noise ratio (CNR) values of MR images obtained were calculated at predetermined time-points. The iron level was detected to access the biodistribution and plasma half-time. RESULTS: In vitro, dual-targeting USPIO nanoparticles bound to proliferating human umbilical vein endothelia cells with high specificity. In vivo, contrast MRI of xenograft mice using dual-targeting nanoparticles demonstrated a significant decrease in signal intensity and a greater increase in CNR than standard MRI and facilitated the imaging of tumor angiogenesis in T2*WI. In terms of biodistribution, dual-targeting USPIO nanoparticles increased to 1.83 times in tumor lesions as compared to the control. And the plasma half-time was about 6.2 h. CONCLUSION: A novel RGD10-NGR9 dual-targeting USPIO has a great potential value as a contrast agent for the identification of tumor angiogenesis on MRI, according to the high specific affinity in vitro and in vivo.

Comparison of tumor neovasculature-targeted paramagnetic nanoliposomes for MRI in mice xenograft models.

INTRODUCTION: Neovasculature imaging is a promising approach for tumor diagnosis. We constructed tumor neovasculature targeted paramagnetic nanoliposomes with RGD10, F56, and K237 peptides, which can bind to Integrin αvß3 and VEGFR-1, VEGFR-2, respectively, and compared their potential value as MRI contrast agents for detecting small tumors in animal models. MATERIALS AND METHODS: Peptide-Ahx-palmitic acid conjugate was synthesized using Fmoc solid-phase synthesis chemistry. Targeted paramagnetic nanoliposomes were prepared by the thin film dispersion-sonication method. The tumor signal enhancements of liposome particles were evaluated by MRI in a xenograft mice model. RESULTS: The apparent affinity constants of RGD10, K237, and F56 peptides binding to their cell receptors were 9.15 × 10(7), 6.01 × 10(7), and 3.85 × 10(7) mol/L, respectively. RGD10 and K237 targeted paramagnetic nanoliposomes have shown much greater tumor-specific MRI signal enhancement in xenograft of the nude mice compared to F56 targeted paramagnetic nanoliposome. Tumor signal enhancement rate (SER %) increased 2.21 ± 0.09 and 1.82 ± 0.05 fold, respectively, for RGD10 and K237 compared to non-targeted control in T1 weighted MR image. CONCLUSION: RGD10 and K237 targeted paramagnetic nanoliposomes can be developed as potential tumor-specific MRI contrast agents and are helpful for tumor detection.