Nanoparticulate Radiolabelled Quinolines Detect Amyloid Plaques in Mouse Models of Alzheimer's Disease

Abstract

Detecting aggregated amyloid peptides (Aβ plaques) presents targets for developing biomarkers of Alzheimer's disease (AD). Polymeric n-butyl-2-cyanoacrylate (PBCA) nanoparticles (NPs) were encapsulated with radiolabelled amyloid affinity I125-clioquinol (CQ, 5-chloro-7-iodo-8-hydroxyquinoline) as in vivo probes. I125-CQ-PBCA NPs crossed the BBB (2.3±0.9 ID/g) (P<.05) in the WT mouse (N = 210), compared to I125-CQ (1.0±0.4 ID/g). I125-CQ-PBCA NP brain uptake increased in AD transgenic mice (APP/PS1) versus WT (N = 38; 2.54×105±5.31×104 DLU/mm2; versus 1.98×105±2.22×104 DLU/mm2) and in APP/PS1/Tau. Brain increases were in mice intracranially injected with aggregated Aβ42 peptide (N = 17; 7.19×105±1.25×105 DLU/mm2), versus WT (6.07×105±7.47×104 DLU/mm2). Storage phosphor imaging and histopathological staining of the plaques, Fe2+ and Cu2+, validated results. I125-CQ-PBCA NPs have specificity for Aβ in vitro and in vivo and are promising as in vivo SPECT (I123), or PET (I124) amyloid imaging agents.