Fig. 2
MSC exosomes attenuate beta cell apoptosis induced by hypoxia. a MSC exosomes promote beta cell survival in a dose-dependent manner. The beta cells were maintained under hypoxia (2% O2, 5% CO2, 37 °C) and treated with different concentrations of MSC exosomes (0, 6.25, 12.5, 25, 50, 100, 200 μg/mL) for 48 h. Cell viability was detected by the CCK-8 method. b, c MSC exosomes attenuate hypoxia-induced beta cell apoptosis. Beta cells were cultured under normoxic (37 °C, 5% CO2, 21% O2) or hypoxic (37 °C, 5% CO2, 2% O2) conditions in the presence or absence of 50 μg/mL MSC exosomes for 48 h (hypoxia + EXO: hypoxia with 50 μg/mL exosomes). The viability of beta cells was determined by staining with AO/PI, the live cells are shown with green fluorescence, and the apoptotic cells are shown with red fluorescence (b). Cell apoptosis was analysed by an annexin V-FITC/PI apoptosis detection kit and flow cytometry (c, d). e The apoptosis-related proteins cleaved caspase 3 and PARP were downregulated, while the apoptosis inhibitor protein survivin was upregulated by MSC exosomes. The results are representative of three independent experiments. Data are expressed as the mean ± SD. *P < 0.05, ***P < 0.01 compared with the hypoxia control group (hypoxia without exosomes)