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Electric and magnetic fields have been known to influence cellular behavior. In the present study, we hypothesized that the application of static magnetic fields to neurons will cause neurites to grow in a specific direction. In cultured human neuronal SH-SY5Y cells or PC12 cells, neurite outgrowth was induced by forskolin, retinoic acid, or nerve growth factor (NGF). We applied static magnetic fields to the neurons and analyzed the direction and morphology of newly formed neuronal processes. In the presence of the magnetic field, neurites grew in a direction perpendicular to the direction of the magnetic field, as revealed by the higher orientation index of neurites grown under the magnetic field compared to that of the neurites grown in the absence of the magnetic field. The neurites parallel to the magnetic field appeared to be dystrophic, beaded or thickened, suggesting that they would hinder further elongation processes. The co-localized areas of microtubules and actin filaments were arranged into the vertical axis to the magnetic field, while the levels of neurofilament and synaptotagmin were not altered. Our results suggest that the application of magnetic field can be used to modulate the orientation and direction of neurite formation in cultured human neuronal cells.

Huntington's disease (HD) has a mitochondrial dysfunction causing the vulnerability to the excitotoxicity and activations of multiple cell death pathways. Recent evidences suggest that the hematopoietic cytokine, granulocyte-colony stimulating factor (G-CSF), exerts pleiotropic neuroprotection in acute neural injury with activating various survival pathways. Thus, we investigated whether G-CSF can modulate neurodegeneration in an HD animal model induced by 3-nitropropionic acid (3NP), which inhibits mitochondrial succinate dehydrogenase complex II. Either G-CSF (50 microg/kg/day) or saline (as vehicle) was administered intraperitoneally for 5 days with 3NP (63 mg/kg/day) continuous osmotic pump infusion into male Lewis rats. We measured motor scales (0-8) daily and sacrificed rats at 5 days. We observed that G-CSF receptors were expressed in 3NP-induced degenerating striatum. Rats treated with G-CSF showed less degree of neurologic deficits. In the G-CSF-treated rats, the striatal lesion volume measured by Nissl staining, TUNEL+ apoptotic cells, Fluorojade C+ degenerating neurons, and c-Jun+ cells were all decreased. In western blotting, G-CSF activated survival pathways including p-ERK, p-eNOS, p-STAT3, and p-Akt. In summary, G-CSF was found to have neuroprotective effects and save striatal cells through activations of survival pathways in the 3NP-induced striatal degeneration model for HD.

Huntington's disease has an increase in the activated calpain, which is enhanced by the NMDA receptor activation. We investigated the neuroprotective effect of memantine in 3-nitropropionic acid (3NP)-induced striatal degeneration model. Either memantine (20 mg/kg/day) or PBS was intraperitoneally administered for five days with 3NP continuous infusion. In the memantine-treated group, the striatal lesion volume, the number of TUNEL+ cells, and Fluoro-Jade C+ degenerating neurons were all decreased. Memantine increased Bcl-xl and decreased Bax level. Memantine also exerted an inhibitory effect on the micro-calpain level and decreased the huntingtin proteolytic fragments. Those rats treated with memantine showed less degree of weight loss at 5 days. Subsequently, memantine was found to have neuroprotective effects and save striatal cells with decreasing calpain levels in the 3NP model of Huntington's disease.

A loss of neostriatal neurons is a characteristic of Huntington's disease (HD), and neural tissue transplantation has been performed directly into the striatum. Since the neural stem cells have ability to migrate into the lesion site, we administered immortalized neural stem-like cells (NSC) into the ventricle or via a tail vein following unilateral intrastriatal quinolinic acid lesioning in Sprague-Dawley rats. To identify transplanted NSC, cells were encoded with lac Z and beta-galactosidase histochemistry was performed. lac Z+ cells were detected in the lesioned striatum but tissue damage or tumor formation was not observed. This study shows that NSC migrate into the striatum, either from ventricle or from the systemic circulation, providing less invasive routes for stem cell application in HD.

Ischemic stroke is caused by the interruption of cerebral blood flow that leads to brain damage with long-term sensorimotor deficits. Stem cell transplantation may recover functional deficit by replacing damaged brain. In this study, we attempted to test whether the human neural stem cells (NSCs) can improve the outcome in the rat brain with intravenous injection and also determine the migration, differentiation and the long-term viabilities of human NSCs in the rat brain. Focal cerebral ischemia was induced by intraluminal thread occlusion of middle cerebral artery (MCA). One day after surgery, the rats were randomly divided into two groups: NSCs-ischemia vs. Ischemia-only. Human NSCs infected with retroviral vector encoding beta galactosidase were intravenously injected in NSCs-ischemia group (5 x 10(6) cells) and the same amount of saline was injected in Ischemia-only group for control. The animals were evaluated for 4 weeks using turning in an alley (TIA) test, modified limb placing test (MLPT) and rotarod test. Transplanted cells were detected by X gal cytohistochemistry or beta gal immunohistochemistry with double labeling of other cell markers. The NSCs-ischemia group showed better performance on TIA test at 2 weeks, and MLPT and rotarod test from 3 weeks after ischemia compared with the Ischemia-only group. Human NSCs were detected in the lesion side and labeled with marker for neurons or astrocytes. Postischemic hemispheric atrophy was noted but reduced in NSCs-ischemia group. X gal+ cells were detected in the rat brain as long as 540 days after transplantation. Our data suggest intravenously transplanted human NSCs can migrate and differentiate in the rat brain with focal ischemia and improve functional recovery.