Imaging of changes in copper trafficking and redistribution in a mouse model of Niemann-Pick C disease using positron emission tomography.

Niemann-Pick C disease (NPC) is an autosomal recessive lysosomal storage disorder resulting from mutations in the NPC1 (95% of cases) or NPC2 genes. Disturbance of copper homeostasis has been reported in NPC1 disease. In this study we have used whole-body positron emission tomography (PET) and brain electronic autoradiography with copper-64 (Cu), in the form of the copper(II) bis(thiosemicarbazonato) complex Cu-GTSM, to image short-term changes in copper trafficking after intravenous injection in a transgenic mouse model of NPC1 disease. Cu-GTSM is taken up in all tissues and dissociates rapidly inside cells, allowing monitoring of the subsequent efflux and redistribution of Cu from all tissues. Significantly enhanced retention of Cu radioactivity was observed in brain, lungs and blood at 15 h post-injection in symptomatic Npc1 transgenic mice compared to wildtype controls. The enhanced retention of Cu in brain was confirmed by electronic autoradiography, particularly in the midbrain, thalamus, medulla and pons regions. Positron emission tomography imaging with Cu in selected chemical forms could be a useful diagnostic and research tool for the management and understanding of NPC1 disease.