Objective  To explore the efficacy and mechanism of using 3-n-butylphthalide (NBP) in combination with bone marrow mesenchymal stem cells (BMSCs) in the treatment of experimental autoimmune encephalomyelitis (EAE) in mice.

  Methods  Myelin oligodendrocyte glycoprotein (MOG35-55) was used for the induction and establishment of the EAE model in C57BL/6 mice. The mice were randomly assigned to the EAE group, which received intraperitoneal injection of phosphate-buffered saline (PBS), the NBP-treated EAE group, or the NBP group, which received intraperitoneal injection of NBP, the BMSCs transplantion EAE group, or the BMSCs group, which received BMSCs injected into the lateral ventricle and intraperitoneal injection of PBS, and the BMSCs and NBP combination treatment EAE group, or the BMSCs+NBP group, which received BMSCs injected into the lateral ventricle and intraperitoneal injection of NBP. Each group had 10 mice, while ten normal mice were used as the blank control group receiving intraperitoneal injection of PBS. The neurological function scores were documented daily. The mice were sacrificed 22 days after EAE induction, and the demyelination state of of the spinal cords was observed through Luxol fast blue (LFB) staining. In addition, the levels of serum interleukin-6 (IL-6), IL-10, IL-17, IL-22 and transforming growth factor-β (TGF-β) were examined with ELISA. The levels of glial fibrillary acidic protein (GFAP), microtubule associated protein-2 (MAP-2) and myelin basic protein (MBP) in the brain were examined with immunofluorescence staining. Western blot was used to check the expressions of nuclear factor (NF)-κB pathway, phosphoinositide-3 kinase (PI3K)/protein kinase B (PKB or Akt) pathway, IL-17 and forkhead box P3 (Foxp3) in the spinal cords.

  Results  The neurological function scores and average scores of each treatment group were significantly lower than those of the EAE group (P<0.05). The scores of the BMSCs+NBP group decreased more significantly than those of the single treatment groups (the NBP group and the BMSCs group) (P<0.05). LFB staining results of the spinal cords were consistent with the neurological function scores and the average scores. Compared with the EAE group, the levels of pro-inflammatory cytokines, including IL-6, IL-17 and IL-22, significantly decreased (P<0.05), and the levels of anti-inflammatory cytokines IL-10 and TGF-β significantly increased (P<0.05). The change in cytokine expression was more significant in the BMSCs+NBP group (P<0.05). The expressions of GFAP, MAP-2 and MBP in the BMSCs+NBP group were significantly higher than those of the BMSCs group (P<0.05). Compared with the EAE group, the p-NF-κB/NF-κB ratio and the IL-17/Foxp3 ratio in NBP group, BMSCs group and BMSCs+NBP group decreased, while P-IκBα/IκBα, p-pI3k/PI3K and P-Akt/Akt ratios increased, especially in the BMSCs+NBP group(P<0.05).

  Conclusion  The combined treatment of NBP and BMSCs can help alleviate the symptoms of EAE model mice, showing better efficacy than treatment with NBP or BMSCs alone. The mechanism is related to the inhibition of the NF-κB pathway to regulate Th17/Foxp3 ratio and the activation of the PI3K/Akt pathway to promote the neurogenic differentiation of BMSCs.