Molecular imaging of neurodegeneration by a novel cross-disease biomarker

Current pre-mortem diagnosis of neurodegenerative disorders such as Alzheimer's disease (AD) or amyotrophic lateral sclerosis (ALS) is based on clinical assessment of neurological deficits. However, symptoms and signs emerge only late in the disease course, thus indicating an urgent need for novel tools for detection of the underlying neuropathology. NST-729 (MW = 310) is a novel molecular imaging probe, which is a member of the ApoSense family of small molecule detectors of apoptosis. We now report on the ability of NST-729, upon its systemic administration in vivo, to detect characteristic neuropathology in pre-clinical models of AD (Tg2576 transgenic mice) and ALS (transgenic SOD-1 G93A mutation mice). In the AD model, NST-729 clearly and selectively bound and imaged amyloid plaques, in excellent correlation with a typical amyloid ex vivo staining (Congo red). In the ALS model, NST-729 distinctly and selectively imaged multiple degenerating neurons in the motor nuclei in the pons, medulla and spinal cord, manifesting numerous multifocal irregularities and disruptions of neuritic projections, typical of axonal apoptosis. Study results therefore support the potential utility of NST-729 as a cross-disease biomarker for neurodegeneration, and also its potential role as the first molecular probe for ALS. Future radio-labeled NST-729 analogues may assist in the early diagnosis of disease, and in the development of neuroprotective therapies for these severe neurological disorders. (C) 2009 Elsevier Inc. All rights reserved.