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Background: Bone marrow mesenchymal stem cells (MSCs) have been found to produce beneficial effects on ischemia-reperfusion injury. However, most of the MSCs died when transplanted into the ischemic tissue, which severely limit their therapeutic potential. Methods: Using an in vitro model of hypoxia and serum deprivation (H/SD), we investigated the hypothesis that sevoflurane preconditioning could protect MSCs against H/SD-induced apoptosis and improve their migration, proliferation, and therapeutic potential. The H/SD of MSCs and neuron-like PC12 cells were incubated in a serum-free medium and an oxygen concentration below 0.1% for 24 h. Sevoflurane preconditioning was performed through a 2-h incubation of MSCs in an airtight chamber filled with 2 vol% sevoflurane. Apoptosis of MSCs or neuron-like PC12 cells was assessed using Annexin V-FITC/propidium iodide (PI). Furthermore, the mitochondrial membrane potential was assessed using lipophilic cationic probe. The proliferation rate was evaluated through cell cycle analysis. Finally, HIF-1α, HIF-2α, VEGF and p-Akt/Akt levels were measured by western blot. Results: Sevoflurane preconditioning minimized the MSCs apoptosis and loss of mitochondrial membrane potential. Furthermore, it increased the migration and expression of HIF-1α, HIF-2α, VEGF, and p-Akt/Akt, reduced by H/SD. In addition, neuron-like PC12 cells were more resistant to H/SD-induced apoptosis when they were co-cultured with sevoflurane preconditioning MSCs. Conclusion: These findings suggest that sevoflurane preconditioning produces protective effects on survival and migration of MSCs against H/SD, as well as improving the therapeutic potential of MSCs. These beneficial effects might be mediated at least in part by upregulating HIF-1α, HIF-2α, VEGF, and p-Akt/Akt. [ABSTRACT FROM AUTHOR]

The present study investigated autophagy changes and the expression of HMGB1 in human glioblastoma cells, responding to carbon-ion beam irradiation (35 keV/μm, 80.55 MeV/u). U251 cells were irradiated with carbon-ion beams and cell proliferation was measured by counting the number of living cells. The expression of Light Chain 3 beta (LC3B), Beclin 1, high-mobility-group box 1 (HMGB1), pro-form caspase-3 and Cellular FLICE-like inhibitory protein (c-FLIP) was analyzed by western blotting. Caspase enzyme activity was determined via a caspase cleavage based florescent substrate commercial Kit. Living cell counting demonstrated a time- and dose-dependent cell death in U251 cells. The expression of LC3B and Beclin 1 revealed that, a high level of autophagy was induced 24 h after irradiation with 1 Gy carbon ions and then decreased in a time- and dose-dependent manner. The expression of the whole HMGB1 showed a well correlation with the dynamic autophagic level. Cytoplasmic HMGB1 maintained autophagy was concluded. Enzyme-Linked Immuno Sorbent Assay (ELISA) measurement found that, HMGB1 was released into the extracellular space in a time- and dose-dependent manner. Lower intracellular HMGB1 levels correlated with decreased autophagy as measured by the expression of LC3B. Decreased expression of pro-form caspase-3 and c-FLIP as well as the increased caspase enzyme activity indicated that apoptosis was induced by carbon-ion beam irradiation. Inhibition of HMGB1 release from the area of intracellular to that of extracellular significantly increased cell survival. In summary, carbon-ion beam irradiation could elevate autophagy and HMGB1 expression efficiently, which would protect the cells from programmed cell death via inducing autophagy. Apoptosis as measured by expression of caspase activities increased as the dose increased, which was accompanied with decreased levels of LC3B and HMGB1. • Carbon-ion irradiation could induce autophagy efficiently. • Apoptosis would be promoted accompanied by reduced autophagy. • Change of HMGB1 shows a good correlation to the autophagic level. • Accumulated HMGB1 protects cell from carbon-ion beam irradiation induced cell death. [ABSTRACT FROM AUTHOR]