by Hisanori Kosuge, Sarah P. Sherlock, Toshiro Kitagawa, Masahiro Terashima, Joëlle K. Barral, Dwight G. Nishimura, Hongjie Dai, Michael V. McConnell
FeCo/graphitic-carbon nanocrystals (FeCo/GC) are biocompatible, high-relaxivity, multi-functional nanoparticles. Macrophages represent important cellular imaging targets for assessing vascular inflammation. We evaluated FeCo/GC for vascular macrophage uptake and imaging in vivo using fluorescence and MRI. Methods and Results
Hyperlipidemic and diabetic mice underwent carotid ligation to produce a macrophage-rich vascular lesion. In situ and ex vivo fluorescence imaging were performed at 48 hours after intravenous injection of FeCo/GC conjugated to Cy5.5 (n?=?8, 8 nmol of Cy5.5/mouse). Significant fluorescence signal from FeCo/GC-Cy5.5 was present in the ligated left carotid arteries, but not in the control (non-ligated) right carotid arteries or sham-operated carotid arteries (p?=?0.03 for ligated vs. non-ligated). Serial in vivo 3T MRI was performed at 48 and 72 hours after intravenous FeCo/GC (n?=?6, 270 µg Fe/mouse). Significant T2* signal loss from FeCo/GC was seen in ligated left carotid arteries, not in non-ligated controls (p?=?0.03). Immunofluorescence staining showed colocalization of FeCo/GC and macrophages in ligated carotid arteries. Conclusions
FeCo/GC accumulates in vascular macrophages in vivo, allowing fluorescence and MR imaging. This multi-functional high-relaxivity nanoparticle platform provides a promising approach for cellular imaging of vascular inflammation.