Synthesis, Chemical Characterization and Multiscale Biological Evaluation of a Dimeric-cRGD Peptide for Targeted Imaging of α V β 3 Integrin Activity

Abstract

Cyclic peptides containing the Arg-Gly-Asp (RGD) sequence have been shown to specifically bind the angiogenesis biomarker α V β 3 integrin. We report the synthesis, chemical characterization, and biological evaluation of two novel dimeric cyclic RGD-based molecular probes for the targeted imaging of α V β 3 activity (a radiolabeled version, 64Cu-NOTA-PEG4-cRGD2, for PET imaging, and a fluorescent version, FITC-PEG4-cRGD2, for in vitro work). We investigated the performance of this probe at the receptor, cell, organ, and whole-body levels, including its use to detect diabetes associated impairment of ischemia-induced myocardial angiogenesis. Both versions of the probe were found to be stable, demonstrated fast receptor association constants, and showed high specificity for α V β 3 in HUVECs (K d ~ 35 nM). Dynamic PET-CT imaging indicated rapid blood clearance via kidney filtration, and accumulation within α V β 3-positive infarcted myocardium. 64Cu-NOTA-PEG4-cRGD2 demonstrated a favorable biodistribution, slow washout, and excellent performance with respect to the quality of the PET-CT images obtained. Importantly, the ratio of probe uptake in infarcted heart tissue compared to normal tissue was significantly higher in non-diabetic rats than in diabetic ones. Overall, our probes are promising agents for non-invasive quantitative imaging of α V β 3 expression, both in vitro and in vivo.

Al18F labeled sulfonamide‐conjugated positron emission tomography tracer in vivo tumor‐targeted imaging

“…No UV absorption peak and radioactive peak of free 18 F or 18 F-Al ion appeared in the HPLC data. The UV absorption peak and radioactive peak of 18…”

“…The cell uptake behavior of 18 F-Al-NOTA-SN to COS-7 and 293T healthy cells (0.432% ± 0.021%, 0.372% ± 0.018%) after the inhibition of SN is similar to that of inhibition of NOTA-SN but the uptake values were slightly lower. However, 18 F-Al-NOTA-SN had far lower cell uptakes to the HepG2, HeLa, and MDA-MB-231 tumor cells, reaching about 0.43% ± 0.021%, 0.501% ± 0.025%, and 0.372% ± 0.018%, respectively after the inhibition of NOTA-SN or SN. Some receptor-binding affinity of 18…”

“…To evaluate the efficiency of 18 F-Al-NOTA-SN on cell growth and metabolism, MTT assays were performed with HepG2, HeLa, MDA-MB-231, COS-7, and 293T cells. As shown in Figure 4, the concentration in 250 µg/mL of 18…”

“…NOTA was synthesized according to the literature. 29 F I G U R E 1 Tumor-targeting imaging strategy of 18…”

“…The tracer was injected into the healthy BALB/C nude though the veil and the biodistribution of it in major organs in vivo was investigated. The in vivo microPET images of healthy mice having received injection with 18 F-Al-NOTA-SN (0.2 mL, 250 μCi) at 1 hour are shown in Figure 6A. PET images showed that the tracer was accumulated in the liver, kidneys, and bladders where indicate a good organ-to-background contrast after 1 hour.…”