Objective: To explore the effects of intraventricular injection of EphB2-Fc on activation of inherent neural stem cells after cerebral cortex infarction.
Methods: Stroke-prone renovascular hypertension model was established in 96 SD rats by two-kidney, two-clip method. Middle cerebral artery occlusion (MCAO) model was established in 72 of these 96 stroke-prone renovascular hypertensive rats and the other 24 rats were used as sham operation group. Then the 72 rats were randomly divided into 3 equal groups: cerebral infarction group without any treatment after the MCAO, MCAO + EphB2-Fc group undergoing stereotaxical infusion of EphB2-Fc at the dose of 20 microl x 200 microg/ml into the lateral ventricle 4 days after the distal ligation of right middle cerebral artery, and MCAO + IgG-Fc group undergoing stereotaxical infusion of IgG-Fc at the dose of 20 microl x 200 microg/ml into the lateral ventricle 4 days after the distal ligation of right middle cerebral artery. By the ends of the first and fourth weeks after the MCAO procedure 12 rats from each group were killed and their brains were taken out to undergo in situ hybridization, immunohistochemistry and Western blotting analysis in order to determine the expression of EphB2 protein and mRNA, nestin and polysialic acid-neural cell adhesion molecule (PSA-NCAM).
Results: One week after the distal ligation of right middle cerebral artery, the EphB2 protein and mRNA expression levels in the ipsilateral cortex and subventricular zone (SVZ) of the cerebral infraction group were both lower than those of the sham operation group (P < 0.05), such levels of the MCAO + EphB2-Fc group were higher than those of the MCAO + IgG-Fc group (both P < 0.05), but there was no significant difference between the cerebral infraction group and IgG-Fc group (both P > 0.05), and there were no differences in such levels between the cerebral infarction group and MCAO + IgG-Fc group (both P > 0.05); the nestin and PSA-NCAM expression levels in the ipsilateral SVZ of the cerebral infraction group were both higher than those of the sham operation group (both P < 0.05), such levels of the MCAO + EphB2-Fc group were both higher than those of the MCAO + IgG-Fc group (both P < 0.05), and migration of PSA-NCAM positive cells to corpus callosum could be seen. Four weeks after, there were no significant differences in the expression levels of EphB2 protein and mRNA among different groups (all P > 0.05), the nestin and PSA-NCAM expression levels in the ipsilateral SVZ decreased in all groups, there were no significant differences in the expression of nestin among all groups, but the PSA-NCAM expression in the ipsilateral SVZ of the cerebral infraction group was still higher than that of the sham operation group.
Conclusion: Disruption of EphB2 signal promotes the proliferation and migration of endogenous neural stem cells in the SVZ after cerebral cortex infarction.