The present study aimed to investigate a possibility of brain repair from diseased or damaged disorders mediated by cell-free filtrate of neural stem cell (NSC) lysates (FNSCL). Mouse NSCs were isolated from the brains of embryos at 15 day postcoitum (dpc). The expression of the Nestin was examined by immunocytochemical technique. Sonication of NSCs cultured and nestin-positive was performed in a bath-type sonicator, and the cell-free filtrate was recovered from a filtrative step of the

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... The animals in the monosodium glutamate MSG group received intragastric(ig) administration of MSG (2.0 g/kg per day) for 10 days the animals in the MSG+NSCs and MSG+FNSCL groups received intracerebroventricular transplantation of 10 µl of NSC suspension, approximately 1.0×10 5 cells, or intracerebroventricular injection of 10 µl of cell-free filtrate of lysates of approximately 1.0×10 5 NSCs on day 1 and day 11 after 10-d MSG exposure, respectively. The mice in control and MSG group were intracerebroventricularly administered with 10 µl of DMEM instead of NSCs or FNSCL. On 11 day after intracerebroventricular transplantation of NSCs or intracerebroventricular injection of FNSCL, the test of Y-maze discrimination learning were performed, and then the histopathology of the animal brains was studied, to analyze MSG-induced functional and morphological changes and the effects of intracerebroventricular transplantation of NSCs or intracerebroventricular injection of FNSCL on the brain repair from MSG-induced excitotoxic injury. Both intracerebroventricular transplantation of NSCs and intracerebroventricular injection of FNSCL facilitated the brain repair following glutamate-induced excitotoxic injury in adult mice, suggesting that there are certain NSC factors inside NSCs which are effective in repairing glutamate-induced excitotoxic brain injury. Administration of FNSCL might be a cell-free-based therapeutic strategy to repair diseased or damaged central nervous system CNS tissue.