Mesenchymal Stem Cells Attenuated Blood-Brain Barrier Disruption via Downregulation of Aquaporin-4 Expression in EAE Mice.

Blood-brain barrier disruption is one of the hallmarks of multiple sclerosis. Mesenchymal stem cells showed great potential for the multiple sclerosis therapy. However, the effect of mesenchymal stem cells on blood-brain barrier in multiple sclerosis remains unclear. Here, we investigated whether mesenchymal stem cells transplantation protected blood-brain barrier integrity and further explored possible underlying mechanisms. Adult female C57BL/6 mice were immunized with myelin oligodendrocyte glycoprotein peptide33-55 (MOG33-55) to induce experimental autoimmune encephalomyelitis (EAE). Mesenchymal stem cells (5 × 10) were transplanted via tail vein at disease onset. In the cell culture, we examined lipopolysaccharide-induced AQP4 upregulation in astrocytes. Results indicated that mesenchymal stem cells therapy improved neurobehavioral outcomes in EAE mice, reduced inflammatory cell infiltration, IgG protein leakage, and demyelination in spinal cord. Mesenchymal stem cells therapy also increased tight junction protein expression. In addition, mesenchymal stem cells downregulated AQP4 and A adenosine receptor (AAR) expression in EAE mice in spinal cord. We found that MSCs-conditioned medium (MCM) reduced the expression of inflammatory cytokines, AQP4 and AAR in lipopolysaccharide-activated astrocytes. BAY-60-6583 (a selective AAR agonist) reversed the MCM-induced AQP4 downregulation and increased p38 MAPK phosphorylation. Furthermore, the upregulation effects of AAR agonist were eliminated when treated with p38 MAPK inhibitor SB203580. Thus, we concluded that mesenchymal stem cells alleviated blood-brain barrier disruption by downregulating AQP4 in multiple sclerosis, possibly through inhibiting the AAR/p38 MAPK signaling pathway. Our work suggests that mesenchymal stem cells exert beneficial effect through maintaining blood-brain barrier integrity in EAE mice.