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 ofNotch1 as well as ofHes1 in this processin vitro.Methods:The experiment was conducted in4 different mediums:NSCs+PBS(GroupA-blank control group),NSCs+SCE with healthySD rats(GroupB-normal control group),NSCs+SCE withSD rats receiving sham-operation treatment (GroupC-sham-operation group) andNSCs+SCE withSCIs rats(GroupD- paraplegic group). Proliferative abilities of4 different groups were analyzed byMTT chromatometry after co-culture for1,2,3,4 and5 d, respectively.The expressions ofNotch1 andHes1 mRNA were also detected withRT-PCR after co-culture for24 and48 h, respectively.Results:After co-culture for1,2,3, 4 and5 d respectively, theMTT values of groupD were significantly higher than those of group A, groupB and groupC(P<0.05).However, there were no significantly differences regardingMTT values between groupA, groupB and groupC after co-culture for1,2,3,4 and5 d, respectively (P>0.05).Both the expressions ofNotch1 andHes1 mRNA of groupD were significantly higher than those of other3 groups after co-culture for24 h and48 h as well(P<0.05).But there was no difference oin expressions ofNotch1 andHes1 mRNA among groupA, groupB and groupC after co-culture for24 h and48 h(P>0.05).There was no difference in expressions ofNotch1 andHes1 mRNA between24 h and48 h treatment in groupD.Conclusions:SCE could promote the proliferation ofNSCs.It is demonstrated that the microenvironment ofSCI may promote the proliferation ofNSCs.Besides,SCE could increase the expression ofNotch1 andHes1 mRNA of NSC.It can be concluded that theNotch signaling pathway activation is one of the mechanisms that locally injured microenvironment contributes to the proliferation ofENSC afterSCIs.This process may be performed by up-regulating the expressions ofNotch1 andHes1gene.