| Background and objective:spinal cord injury(SCI)is a disease of the central nervous system caused by trauma,infection,ischemia or related lesions,with an extremely high rate of disability and fatality,which places a heavy burden on the family and society.How to regenerate and repair the damaged nerve structure that promotes the recovery of neurological deficits,especially the motor disorder,is still a difficult point and research hotspot in the current treatment.It has been shown that human umbilical cord mesenchymal stem cells(hUC-MSCs)can be transplanted for the treatment of SCI,but few of these studies have explored the optimal time and mechanism of transplantation.The purpose of this study was to determine the optimal time-window for the treatment of spinal cord injured rats with hUC-MSCs and the changes of the expression of induced nitric oxide synthase(iNOS)to provide a reference for clinical application.Methods:hUC-MSCs were acquired and cultivated by adherent method,and SCI model was made through modified Allen method.45Sprague-Dawley rats were randomly divided into three groups:sham-operated group,model group and hUC-MSCs group,15 ones in each group.The T8 to T10 vertebral plates were exposed in the sham-operated group;we hit the spinal cord in the model group;and the hUC-MSCs group was divided into 0 h group,8 h group,48 h group,1 w group and 2 w group according to the time of cell transplantation after SCI,3 rats in each group,1×10~6/ml×1ml hUC-MSCs was injected into the tail vein respectively.The motor function scores of hind limbs of rats in all groups were evaluated by BBB scale on the 3,7,14,21 and 28 days after intervention,while finished the evaluation,the spinal cord specimens were collected by cardiac perfusion method and the expression of iNOS was measured by blotting.T test in SPSS software was used to explore the efficacy of hUC-MSCs in the treatment of SCI in rats.The best time of transplantation and the change regulation of iNOS were found out by comparing the differences in motor function scores of rats after hUC-MSCs implantation in each time window within the transplantation group,.Results:With the passage of time,while the BBB scores had no obvious change in the sham-operated group,the model group and the hUC-MSCs group gradually increased,especially between the first and second week after injury.The BBB scores of the model group and hUC-MSCs group was lower and the expression of iNOS mRNA had a higher level than that in the sham-operated group;compared with the model group,the hUC-MSCs group had a significantly increase in BBB scores(P<0.05)and the iNOS mRNA was reduced;among the hUC-MSCs group,the BBB scores of 48 h group and 1 w group increased more obviously and the expression of iNOS was in a lower level compared with the other groups.Discussion:the results of this research indicate that hUC-MSCs transplantation is relatively safe and effective for the treatment of SCI in rats.It may be more available to transplant at the time of 48 h or 1 w after SCI,a randomized controlled study of large samples is required. |
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