RGD targeting of human ferritin iron oxide nanoparticles can enhance in vivo carotid MRI of experimental atherosclerosis

2) RGD-conjugated HFn-iron oxide nanoparticles Using the recombinant human heavy-chain ferritin protein cage, HFn was genetically engineered to display 24 copies of an RGD-4C peptide (CDCRGDCFC) on the exterior surface of the protein cage. Magnetite (Fe3O4) was encapsulated in interior cavities of RGD-conjugated HFn (RGD HFn) and non-targeted HFn (RGD HFn) at loading factors of 5000Fe per cage, giving R2 values of 93 mMs (magnetite diameter: 5-7nm, exterior diameter: 12nm). The injected dose was adjusted to 25mgFe/kg. 3) MRI Two weeks post ligation, mice were imaged on a wholebody 3T MRI scanner (Signa HDx, GE Healthcare) with a phased array mouse coil (RAPID MR International), using a gradient echo sequence (TR/TE=100ms/10ms, slice thickness=1.0mm, FOV=3cm, matrix=256x256, FA=60, NEX=10). Mice were then injected with either RGD (n=7) or RGD (n=7) HFn nanoparticles, followed by MRI at 24 and 48 hours post injection. The nanoparticle accumulation was assessed by measuring the extent of T2*-induced reduction in carotid lumen size (% reduction of carotid lumen area).