Effect of spinal cord extracts after spinal cord injury on proliferation of rat embryonic neural stem cells and Notch signal pathway in vitro.

Objective: To investigate the effect of the spinal cord extracts (SCE) after spinal cord injuries (SCIs) on the proliferation of rat embryonic neural stem cells (NSCs) and the expressions of mRNA of Notch1 as well as of Hes1 in this process in vitro.

Methods: The experiment was conducted in 4 different mediums: NSCs+PBS (Group A-blank control group), NSCs+SCE with healthy SD rats (Group B-normal control group), NSCs+SCE with SD rats receiving sham-operation treatment (Group C-sham-operation group) and NSCs+ SCE with SCIs rats (Group D-paraplegic group). Proliferative abilities of 4 different groups were analyzed by MTT chromatometry after co-culture for 1, 2, 3, 4 and 5 d, respectively. The expressions of Notch1 and Hes1 mRNA were also detected with RT-PCR after co-culture for 24 and 48 h, respectively.

Results: After co-culture for 1, 2, 3, 4 and 5 d respectively, the MTT values of group D were significantly higher than those of group A, group B and group C (P<0.05). However, there were no significantly differences regarding MTT values between group A, group B and group C after co-culture for 1, 2, 3, 4 and 5 d, respectively (P>0.05). Both the expressions of Notch1 and Hes1 mRNA of group D were significantly higher than those of other 3 groups after co-culture for 24 h and 48 h as well (P<0.05). But there was no difference oin expressions of Notch1 and Hes1 mRNA among group A, group B and group C after co-culture for 24 h and 48 h (P>0.05). There was no difference in expressions of Notch1 and Hes1 mRNA between 24 h and 48 h treatment in group D.

Conclusions: SCE could promote the proliferation of NSCs. It is demonstrated that the microenvironment of SCI may promote the proliferation of NSCs. Besides, SCE could increase the expression of Notch1 and Hes1 mRNA of NSC. It can be concluded that the Notch signaling pathway activation is one of the mechanisms that locally injured microenvironment contributes to the proliferation of ENSC after SCIs. This process may be performed by up-regulating the expressions of Notch1 and Hes1 gene.