ABSTRACT
Objective To investigate the role of methylprednisolone (MP) in treatment of spinal cord injured (SCI) with bone marrow mesenchymal stem cells (BMSCs) transplantation in rats and its effect on the expressions of tumor necrosis factor-α(TNF-α) and interleukin-1β(IL-1β) at the local tissues.Methods Forty male Sprague-Dawley(SD) rats were used to establish the models of SCI according to the modified Allen's contusion method and then divided into four groups (n=10 in each group) by using random numbers table:MP group,BMSCs group,BMSCs+MP group,and control group.MP was intravenously administrated immediately after SCI.BMSCs labeled by 5-bromo-2-deoxyuridine(BrdU)were transplanted into the injured sites of spinal cord after two hours of SCI.On the 1 st,7 th,and 14th days after SCI,when functional outcome measurements were evaluated by the Basso-Beattie-Bresnahan (BBB) score.On the 14th day after treatment,the spine cord tissues were harvested for the TNF-α/IL-1β immunohistochemistry,and Tunel staining method was used to detect cell apoptosis rate.BrdU-positive BMSCs were examined in BMSCs group and BMSCs+MP group.Results Functional recovery of hind limb in MP+BMSCs group was the best among the four group.On the 1 st day after injury,the BBB scores showed no significant difference among four group(χ=1.0756,P=0.7829).On the 7th and 14th day,the BBB score of MP+BMSCs group was significantly higher than MP group (χ=17.7186,P=0.0002;χ= 24.7259,P<0.0001) and BMSCs group (χ=15.8110,P=0.0024;χ=25.6014,P<0.0001),respectively.The BBB score of the control group was significantly lower than MP group (χ=8.3265,P=0.0325;χ=13.5060,P=0.0062) and BMSCs group (χ=14.1166,P=0.0036;χ=8.9613,P=0.0299),respectively.On the 14th day,immunohistochemical staining presented that the TNF-α and IL-1β-positive cells in MP+BMSCs group were significantly lower than MP group (q=5.573,P=0.0004;q=4.596,P=0.0025) and BMSCs group (q=13.780,P<0.0001;q=8.456,P<0.0001),and control group was significantly higher than MP group (q=14.710,P<0.0001;q=6.710,P<0.0001) and BMSCs group (q=6.502,P=0.0001;q=2.849,P=0.0514).Tunel staining showed the apoptotic rate of spinal cord cells in four group were (48.47±5.70)%,(31.95±3.58)%,(41.39±2.33)%,and (23.48±2.69)%.The number of apoptotic cells in MP+BMSCs group was least in four groups;compared with the control group,the apoptotic rate significantly decreased in MP group (q=14.840,P<0.0001) and BMSCs group (q=6.716,P=0.0002);compared with the MP+BMSCs group,the apoptotic rate was significantly increased in the MP group (q=7.332,P=0.0001) and BMSCs group (q=15.460,P<0.0001). BrdU staining revealed BrdU-positive rate in MP+BMSCs group [(9.3000±0.5175)%] was significantly higher than that in BMSCs group [(6.6000±0.3399)%](t=4.361,P=0.0004).Conclusion MP can improve the function of the hind limbs of SCI rats treated with BMSCs transplantation and lower the expressions of TNF-α and IL-1β in injured tissue.