ABSTRACT
Objective@#To explore the inhibitory effect of exosomes secreted by human umbilical cord mesenchymal stem cells(HUCMSC) on apoptosis of human umbilical vein endothelial cells(HUVEC) after model group(oxygen-glucose deprivation reoxygenation), and to clarify its possible mechanism.@*Methods@#Human umbilical cord mesenchymal stem cells were cultured. The collected cell supernatant was stored in a centrifugal tube. The exosomes secreted by human umbilical cord mesenchymal stem cells were extracted by ultracentrifugation and identified. Human umbilical vein endothelial cells were randomly divided into control group, model group and different concentrations of HUCMSC-EXO(20 μg/ml, 40 μg/ml, 60 μg/ml) treatment groups(adding HUCMSC-EXO into the model group) . The morphological changes of HUVEC cells in each group were observed by inverted phase contrast microscope, and the proliferation inhibition rate of HUVEC in each group was measured by CCK-8 reagent. Western blot was used to detect the expression of apoptosis-related proteins Caspase-3, Bax, Bcl-2 and hypoxia-associated protein hypoxia inducible factor 1α(HIF-1α). Inhibitor(HIF-1α inhibitor) + model group and HUCMSC-EXO + inhibitor + model group were added on the basis of the above experiments. Western blot analysis was performed to observe the effects of HUCMSC-EXO, inhibitor and both of them on HIF-1α and Bax expressions in HUVEC.@*Results@#HUCMSC-EXO was successfully extracted and identified. Compared with the control group, the volume of HUVEC in the model group and the HUCMSC-EXO group with different concentrations decreased, became round, connected and evacuated, and the growth state was poor under the inverted phase contrast microscope.CCK-8 detection showed that the cell viability in the HUCMSC-EXO group was significantly higher than that in the model group, the difference was statistically significant (t=9.23, P<0.05). Western blot analysis showed that compared with the control group, the expression levels of Caspase-3 ((0.296±0.038), (0.879±0.088); t=14.92, P<0.05), Bax((0.234±0.034), (0.762±0.084); t=14.36, P<0.05) of HUVEC in the model group were up-regulated, and the expression level of Bcl-2 was down-regulated ((0.863±0.103), (0.387±0.059); t=9.85, P<0.05), with statistically significant differences. Compared with the model group, the expression levels of Caspase-3( (0.586±0.075); t=6.24, P<0.05), Bax((0.311±0.055); t=11.01, P<0.05) and Bcl-2((0.665±0.071); t=7.45, P<0.05) of HUVEC in the HUCMSC-EXO treatment group were down-regulated and the differences were statistically significant. Inhibitor intervention experiments showed that there were no significant differences between the inhibitor+ model group and HUCMSC-EXO+ inhibitor+ model group in the expression of HIF-1α protein ((0.348±0.055), (0.388±0.077); t=1.04, P>0.05)and Bax protein ((0.363±0.069), (0.370±0.064); t=0.18, P>0.05). But both of them were down-regulated compared with the model group (HIF-1α protein (0.919±0.064), Bax protein (0.902±0.071)), the differences were significant( t=13.56, t=13.03, both P<0.05).@*Conclusion@#HUCMSC-EXO has a protective effect on OGD/R model of HUVEC, and its mechanism may be related to the down-regulation of HIF-1α expression.
ABSTRACT
AIM:To explore the protective effects of exosome secreted by human umbilical mesenchymal stem cells on cardiac fibrosis in diabetic mouse model.METHODS:Male C57BL/6 mice at 6～8 weeks of age were divided in-to 3 groups randomly:control group ,diabetes mellitus(DM)group and DM+exosome group.To develop mouse DM mo-del,the mice were fed with high-fat diet for 5 weeks,followed by intraperitoneal injection of 45 mg/kg streptozocin once a week for 5 weeks.It was considered as a successful DM model that the blood glucose of the mice was ≥16.7 mmol/L.The mice in DM+exosome group were injected with exosome via tail vein.The mice in other 2 groups were injected with saline at the same volume.The heart function was evaluated by color Doppler echocardiography for small animals.The blood sam-ples were collected from abdominal aortas.The blood glucose and non-esterified fatty acids were measured by biochemical colorimetric assay.HE staining was performed to observe the structural changes of myocardial fibers ,and Masson staining was used to observe the cardiac fibrosis.RESULTS:The results of echocardiography showed that left ventricular end-dias-tolic dimension(LVIDd)and left ventricular end-systolic dimension(LVIDs)of diabetic mice were larger than those incontrol mice(P<0.05 and P<0.01,respectively).The ejection fraction(EF)and fractional shortening(FS)decreased in the diabetic mice(P<0.01).Exosome treatment significant decreased the LVIDs(P<0.01),but increased the EF and FS(P<0.01).The blood glucose and non-esterified fatty acids were significantly increased in the diabetic mice.The injection of the stem cell exosome significantly decreased the blood glucose and non -esterified fatty acids(P<0.01).HE staining observation showed that cardiomyocyte hypertrophy and fragmentation of cardiomyocyte in DM group were more se -rious than those in control group.Masson staining showed that the area of fibrosis in DM group was larger than that in con-trol group(P<0.01),but that in DM+exosome group was reduced(P<0.01).CONCLUSION:Exosome secreted by human umbilical mesenchymal stem cells protects the DM model mice from cardiac fibrosis.