Ischemic preconditioning potentiates the protective effect of mesenchymal stem cells on endotoxin-induced acute lung injury in mice through secretion of exosome.

OBJECTIVE To explore the effect of bone marrow mesenchymal stem cells (MSCs) on endotoxin-induced acute lung injury in mice and verify the role of exosome. METHODS Exosome was isolated from the culture supernatant of MSC. For ischemic preconditioning, MSCs were subjected to anoxia for 0 min (MSCs group), 30 min (MSCs(IPC-30) group), 60 min (MSCs(IPC-60) group) and 90 min (MSCs(IPC 90) group), and then used to treat endotoxin-injured mice. The exosome from the optimal group was used to treat endotoxin-injured mice. In addition, the exosome from the optimal group was also used to treat the endotoxin-stimulated RAW 264.7 cells for 6 h and 12 h. RESULTS CD63 positive exosome were acquired through ExoQuick kits. Administration of MSCs, MSCs(IPC-30), MSCs(IPC-60) and MSCs(IPC-90) could reduce the level of white blood cells (WBC) and neutrophils into the bronchoalveolar lavage (BAL) fluid of endotoxin-injured mice, and the MSCIPC-60 group had the greatest reduction, which reduced WBC by 57% and neutrophils by 55%. Administration of MSCs(IPC-60) exosome could also reduce the level of WBC, neutrophils, MIP-2 and penetration protein into the BAL fluid of endotoxin-injured mice, which had the same effect as MSCs(IPC-60) and showed a dose dependent, compared to MSCs exosome. In addition, MSCs(IPC-60) exosome were used to treat endotoxin-stimulated RAW 264.7 cells, and the level of TNFα at 6 h and 12 h was significantly reduced, while the level of IL-10 at 12 h increased. CONCLUSION Ischemic preconditioning for 60 min can potentiates the protective effect of MSC on endotoxin-induced Acute Lung Injury through the secretion of Exosome.