Near-infrared fluorescence imaging of apoptotic neuronal cell death in a live animal model of prion disease.
Apoptotic cell death via activation of the caspase family of cysteine proteases is a common feature of many neurodegenerative diseases including Creutzfeldt-Jakob disease. Molecular imaging of cysteine protease activities at the preclinical stage may provide valuable mechanistic information about pathophysiological pathways involved in disease evolution and in response to therapy. In this study, we report synthesis and characterization of a near-infrared (NIR) fluorescent contrast agent capable of noninvasively imaging neuronal apoptosis in vivo, by conjugating a NIR cyanine dye to Val-Ala-Asp-fluoromethylketone (VAD-fmk), a general inhibitor of active caspases. Following intravenous administration of the NIR-VAD-fmk contrast agent, in vivo fluorescence reflectance imaging identified significantly higher levels of active caspases in the brain of mice with advanced but preclinical prion disease, when compared with healthy controls. The contrast agent and related analogues will enable the longitudinal study of disease progression and therapy in animal models of many neurodegenerative conditions.
Department of Pathology, University of Melbourne, Victoria 3010, Australia; Mental Health Research Institute, Parkville, Victoria 352, Australia.
Victoria A
VA
Lawson
Cathryn L
CL
Haigh
Blaine
B
Roberts
Vijaya B
VB
Kenche
Helen M J
HM
Klemm
Colin L
CL
Masters
Steven J
SJ
Collins
Kevin J
KJ
Barnham
Simon C
SC
Drew
D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D015153:Blotting, Western; D002232:Carbocyanines / Q000138:chemical synthesis; D020169:Caspases / Q000378:metabolism; D005456:Fluorescent Dyes; D006801:Humans; D007150:Immunohistochemistry; D007259:Infrared Rays; D051379:Mice; D008807:Mice, Inbred BALB C; D008856:Microscopy, Fluorescence; D059906:Neuroimaging / Q000379:methods*; D009474:Neurons / Q000473:pathology*; D009842:Oligopeptides / Q000138:chemical synthesis; D017096:Prion Diseases / Q000473:pathology*
D002232:Carbocyanines; D005456:Fluorescent Dyes; C582724:NIR-VAD-fmk; D009842:Oligopeptides; D020169:Caspases