To investigate the inhibitory role of mesenchymal stem cells-derived exosomes (MSC-Exo) in the activation of hippocampal astrocytes.

Exosomes were isolated from umbilical cord MSCs by ultra-speed centrifugation, and labeled by PKH-26 dye. The primary hippocampal astrocytes were pretreated with MSC-Exo and then stimulated by lipopolysaccharide (LPS) to induce cell activation, as well as divided into control group, LPS group and LPS+MSC- Exo group. Immunocytochemistry and immunoblotting were used to detect the expression of C3 and GFAP, and ELISA was used to test the expression of interleukin (IL) -1β, tumor necrosis factor (TNF) -α and IL- 6. One way ANOVA and least significant difference (LSD) test were used for statistical analysis.

The results showed that the MSC-Exo presented normal biological characteristics of exosomes, as well as exhibited the capacity to integrate into the soma and processes of astrocytes. Compared with the control group, the expression of glial fibrillary acidic protein (GFAP) (1.47±0.15 vs 0.95±0.17, P < 0.01) , A1 phenotype of astrocyte marker C3 (1.32±0.23 vs 0.87±0.16, P < 0.05) , IL-1β [ (282.90±5.13) pg/ mL vs (252.53±5.51) pg/mL, P < 0.05], TNF-α [ (128.26±1.89) pg/mL vs (111.86±2.84) pg/mL, P < 0.01] and IL-6 [ (180.95±3.16) pg/mL vs (163.95±3.71) pg/mL, P < 0.05] were significantly increased after stimulation with LPS. The pre-treatment with MSC-Exo could reduce the expression of GFAP (0.97±0.16 vs 1.47±0.15, P < 0.01) , C3 (0.83±0.12 vs 1.32±0.23, P < 0.01) , IL-1β [ (262.20±2.64) pg/mL vs (282.90±5.13) pg/mL, P < 0.05], and TNF-α [ (120.79±0.42) pg/mL vs (128.26±1.89) pg/mL, P < 0.05], but there was no significant change of IL-6 [ (187.2±0.64) pg/mL vs (180.9±3.16) pg/mL, P > 0.05].

MSC-Exo has inhibitory effect on the activation of hippocampal astrocytes.