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, ie, 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.