Background: Despite encouraging data in terms of neurological outcome, stem cell based therapy for ischemic stroke in experimental models and human patients is still hampered by multiple as yet un-optimized variables, i.e., time of intervention, that significantly influence the prognosis. The aim of the present study was to delineate the optimum time for neural stem cells (NSCs) transplantation after ischemic stroke. Methods:The NSCs were isolated from 14 days embryo rat ganglion eminence and were cultured in NSA medium (neurobasal medium, 2% B27, 1% N2, bFGF 10 ng/mL, EGF 20 ng/mL and 1% pen/strep). The cells were characterized for tri-lineage differentiation by immunocytochemistry for tubulin-III, Olig2 and GFAP expression for neurons, oligodendrocytes and astrocyte respectively. The NSCs at passage 3 were injected intraventricularly in a rodent model of middle-cerebral artery occlusion (MCAO) on stipulated time points of 1 & 12 h, and 1, 3, 5 and 7 days after ischemic stroke. The animals were euthanized on day 28 after their respective treatment.Results: dUTP nick end labeling (TUNEL) assay and Caspase assay showed significantly reduced number of apoptotic cells on day 3 treated animals as compared to the other treatment groups of animals. The neurological outcome showed that the group which received NSCs 3 days after brain ischemia had the best neurological performance. Conclusions:The optimum time for NSCs transplantation was day 3 after ischemic stroke in terms of attenuation of ischemic zone expansion and better preserved neurological performance.

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Purpose: Some reports have shown neuroprotective effects of caffeine in several neurodegenerative disorders. However, its mechanism of action is not completely clear. Therefore, the aim of this study was to explore the interference of ryanodine, N-methyl-D-aspartate (NMDA) and adenosine modulators with the neuroprotective effects of caffeine against β-amyloid (Aβ) neurotoxicity in the SHSY5Y cells.Methods: The SHSY5Y cells were treated with Aβ23-35 (20µM) and/or caffeine (0.6 and 1mM), or both for 24 hours. Adenosine (20, 40, 60, 80, 100µM), NMDA (20, 50, 70, 90µM), dantrolene (2, 4, 6, 8, 10µM) were also added to the medium and incubated for 24 hours. The cell viability was measured via the MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide) method. The data were analyzed using one-way ANOVA followed by Bonferroni test.Results: Caffeine at all the used concentrations (0.6, 0.8, 0.9, 1, and 3mM) significantly protected neuronal cells against Aβ neurotoxicity. Adenosine at the concentrations of 20, 40, 80 and 100μM diminished the neuroprotective effects of caffeine (0.6 and 1mM) against Aβ neurotoxicity. NMDA at the concentrations of 20, 50, 70 and 90μM blocked caffeine (0.6 and 1mM) neuroprotective effects. Dantrolene at the concentration of 2, 4, 6, 8 and 10μM diminished the neuroprotective effects of caffeine (0.6mM) and at the concentrations of 2 and 10μM impede caffeine (1mM) neuroprotection against Aβ neurotoxicity.Conclusion: Caffeine produced neuroprotective effect against Aβ neurotoxicity. Blockade of adenosine and NMDA receptors, as well as the activation of ryanodine receptors, may contribute to the neuroprotective effects of caffeine.