PiB-Conjugated, Metal-Based Imaging Probes: Multimodal Approaches for the Visualization of β-Amyloid Plaques.
ACS Med Chem Lett 2013;
4:436-40. [PMID:
24900692 DOI:
10.1021/ml400042w]
[Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Accepted: 04/14/2013] [Indexed: 01/19/2023] Open
Abstract
In an effort toward the visualization of β-amyloid plaques by in vivo imaging techniques, we have conjugated an optimized derivative of the Pittsburgh compound B (PiB), a well-established marker of Aβ plaques, to DO3A-monoamide that is capable of forming stable, noncharged complexes with different trivalent metal ions including Gd(3+) for MRI and (111)In(3+) for SPECT applications. Proton relaxivity measurements evidenced binding of Gd(DO3A-PiB) to the amyloid peptide Aβ1-40 and to human serum albumin, resulting in a two- and four-fold relaxivity increase, respectively. Ex vivo immunohistochemical studies showed that the DO3A-PiB complexes selectively target Aβ plaques on Alzheimer's disease human brain tissue. Ex vivo biodistribution data obtained for the (111)In-analogue pointed to a moderate blood-brain barrier (BBB) penetration in adult male Swiss mice (without amyloid deposits) with 0.36% ID/g in the cortex at 2 min postinjection.
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