The purpose of this study is to investigate whether a near-infrared fluorescence (NIRF) probe, Cy5.5-D-glucosamine (Cy5.5-2DG), can image arthritis in collagen-induced arthritic (CIA) mice. The presence of arthritis was verified by both visual examination and micro-computed tomography (MicroCT) imaging. CIA mice were imaged by a micro-positron emission tomography (MicroPET) scanner one hour after intravenous injection of 2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG). After radioactivity of [18F]FDG decayed away, Cy5.5-2DG was injected into a lateral tail vein of the mice. Arthritic tissue targeting and retention of Cy5.5-2DG in CIA mice were evaluated and quantified by an optical imaging system. Inflammatory tissue in CIA mice was clearly visualized by [18F]FDG-MicroPET scan. NIRF imaging of Cy5.5-2DG in the same mice revealed that the pattern of localization of Cy5.5-2DG in the arthritic tissue was very similar to that of [18F]FDG. Quantification analysis further showed that [18F]FDG uptake in arthritic tissues at one hour post-injection (p.i.) and Cy5.5-2DG uptakes at different time points p.i. were all well correlated (r2 over 0.65). In conclusion, Cy5.5-DG can detect arthritic tissues in living mice. The good correlation between the [18F]FDG uptake and Cy5.5-2DG accumulation in the same arthritic tissue warrants further investigation of Cy5.5-2DG as an approach for assessment of anti-inflammatory treatments.
Bibliographical noteFunding Information:
This work was supported, in part, by National Natural Science Foundation of China (Grant No. 90508003), National Cancer Institute (NCI) Small Animal Imaging Resource Program (SAIRP) Grant R24 CA93862, and NCI In Vivo Cellular Molecular Imaging Center (ICMIC) Grant P50 CA114747 (SSG).
- Near-infrared fluorescence
- fluorescent deoxyglucose