Alteration of adult neural stem cells by gold nanoparticles in a demyelination model induced in the hippocampus of adult male mice: a structural and ultrastructural study

Adult neural stem cells (NSCs) are located in the sub-granular zone (SGZ) of the dentate gyrus (DG) of the hippocampus, one of the prominent regions of neurogenesis in the adult brain. Activation of endogenous stem cells may provide a therapeutic approach in demyelinating diseases. Due to their minuscule size, nanoparticles (AuNPs) can cross the blood-brain barrier. To evaluate the effect of AuNPs on adult NSCs and the progression of demyelination in the hippocampus in a model of demyelination, thirty-two adult mice were divided into: control group I, AuNPs group II (10 mg/kg BW/day), cuprizone (CPZ) group III (0.2% orally for 8 weeks to induce demyelination), and CPZ & AuNPs group IV. Hippocampus was prepared for light microscopy, nestin immunohistochemical staining (NSCs' immune marker), and electron microscopy. In groups I and II, spindle-shaped adult NSCs in the SGZ of DG showed a positive nestin immunoreaction. In group III, most of the nerves were demyelinated. Pyramidal and granular neurons showed degenerative changes. Nestin-immune-positive cells were significantly decreased. In group IV, preservation of the myelin, less degenerative changes, and a significant increase in nestin-positive cells were detected. In conclusion, AuNPs activated adult NSCs in the mouse hippocampus, partially ameliorated degenerative changes, and enhanced partial remyelination in the CPZ demyelination model.