Magnetic resonance tracking of nanoparticle labelled neural stem cells in a rat's spinal cord

Neural stem cells isolated from an adult rat's spinal cord were loaded with superparamagnetic gold-coated monocrystalline iron oxide nanoparticles (Au-MION) intended for use as contrast enhancers in magnetic resonance imaging (MRI). A dose-dependent attenuation of MRI signals was observed for Au-MION down to 0.001 mu gFe/mu l and for nanoparticle-loaded clusters of only 20 cells. The labelled cells were infused into the spinal cord of anaesthetized rats and tracked by MRI at 1 h, 48 h and 1 month post-injection. Histological analysis revealed that MRI signals correlated well with gold-positive staining of transplanted cells. The present results show that Au-MION exerts powerful contrast-enhancing properties and may represent novel MRI labels for labelling and tracking the transplanted cells in vivo.