Adipose-derived mesenchymal stem cell-derived exosomes markedly protected the brain against sepsis syndrome induced injury in rat

This study tested the hypothesis that sepsis syndrome [SS-induced by cecal-ligation and puncture (CLP)]-induced systemic inflammation and brain damage in rats were effectively suppressed by allogenic adipose-derived mesenchymal stem cell-derived exosome (AMSC^EXO). SD rats (n = 72) were divided into group 1 [sham-control (SC)], group 2 (SS only) and group 3 (SS + AMSC^EXO) and equally euthanized at 6/24/48/72 h after SS induction, respectively. By 6/16/24/72 h, flow cytometric analyses demonstrated the numbers of inflammatory cells (Ly6G+/CD11^b/ c +), immune (CD3+/CD4+ cells/CD3+/CD8+ cells) and early (AN-V+/PI-)/late (AN-V+/PI+) apoptotic cells in circulation were significantly increased in group 2 than in groups 1 and 3, and significantly increased in group 3 than in group 1, whereas the number of T-reg+ cells was significantly progressively increased from groups 1 to 3 (all P < 0.0001). At 6/16/24/72 h, the numbers of (CD3+/CD4+ cells/CD3+/CD8+ cells/T-reg+ cells) in spleen exhibited an identical pattern of circulation among the three groups (all P < 0.0001). ELISA showed inflammatory mediators (IL-6/TNF-α) in circulating/cerebrospinal fluid at 6/24/72 h displayed an identical trend as the immune cells among the three groups (all P < 0.0001). Microscopic findings demonstrated that the cellular expressions of inflammatory (F4/80+//MMP-9+//CD14+//GFPA+) and brain-damaged (AQP4+/γ-H2AX+) biomarkers at 24/72 h exhibited an identical pattern of immune cells among the three groups (all P < 0.0001). The protein expressions of inflammatory (IL-1β/MMP-9/TNF-α/NF-κB/TLR2/TLR-4/MyD88/HMGB1), apoptotic (cleaved-caspase3/PARP/mitochondri-al-Bax) and oxidative-stress (NOX-1/NOX-2/oxidized protein) biomarkers displayed an identical pattern as the immune cells among the three groups (all P < 0.0001). In conclusion, SS elicited vigorously inflammatory reaction not only in circulation but also in spleen/brain, resulting in serious brain damage.