Human Umbilical Cord Mesenchymal Stem Cells Up-regulate Autophagy And Exert Renal Protection

Objective To investigate whether human umbilical cord mesenchymal stem cells(hUC-MSCs)can protect renal function in diabetic rats by regulating autophagy.Methods Type 2 diabetic rats model was induced by a high-fat diet combined with a low dosage of streptozotocin(STZ)intraperitoneal injection.After successful modeling,those rats were fed with a high-fat diet for another eight weeks,and the control group(10)was given a normal chow diet.The treatment group(MSCs group,10)was infused hUC-MSCs(3×106 suspended in 0.5 ml PBS)via tail vein once every two weeks,for a total of eight weeks of treatment.The diabetic control group(T2DM group,10)was infused 0.5 ml PBS solution via tail vein and the control group did not receive any treatment at the same time.Random blood glucose and body weight were monitored every two weeks while the 24 hours urine protein/creatinine(Alb/Cr)was monitored every four weeks.One week after the fourth treatment,intraperitoneal glucose tolerance test(IPGTT)was performed on all rats,and later on they were sacrificed and their kidneys were collected for histopathological examinations and autophagy-related protein examinations.Data was mesured by two independent sample mean t tests,one-way ANOVA and repeated measures analysis of variance.Results Compared to T2DM group,random blood glucose decreased[(23.9±3.7)ratio(28.7±2.1)mmol/L,t=3.568,P<0.01],and glucose tolerance improved(P<0.01,t=3.07?6.64).),24 h urine Alb/Cr decreased[(0.07±0.03)ratio(0.612±0.12)g/mmol,t=12.96,P<0.01]in MSCs group.The pathological results showed that in the MSCs group the degree of glomerular sclerosis was reduced(P<0.01,t=17,28),the glomerular basement membrane thickening was relieved(P<0.01,t=12.00),and the degree of renal interstitial fibrosis was improved(P<0.01,t=2.83?6.85).Electron microscopy pictures showed that the damage of glomerular ultrastructure was significantly reduced in MSCs group,which showed that the endothelial cell window structure was improved,the basement membrane thickening was reduced,and the footprocess structure was regular and complete.Immunofluorescence stains of autophagy-related proteins showed that the MSCs group exhibited increased expression of LC3[(78.3±5.3)%?(33.4±8.3)%,P<0.01,t=10.22]and reduced expression of P62[(24.1±4.2)%?(93.3±4.9)%,P<0.01,t=24.13].Results of western blot showed expressions of LC3 in MSCs group increased[(0.793±0.048)VS(0.442±0.041),P<0.01,t=5.57],and the lc3-?/I ratio increased significantly[(12.1±0.488)VS(0.313±0.036),P<0.01,t=24.08],and the P62 level decreased significantly[(0.019±0.001)VS(1.239±0.041),P<0.01,t=29.84].Those results above indicated that the level of autophagy in rat kidneys were significantly increased after MSCs infusion.Conclusion Treatment of hUC-MSCs can exert renal protection and delay the development of diabetic nephropathy,which may be related to the enhancement of autophagy in renal tissues.