脐带间充质干细胞对2型糖尿病大鼠的治疗作用及机制研究

Therapeutic effect of umbilical cord derived mesenchymal stem cells and their mechanisms in type 2 diabetic rats

目的探索多次输注间充质干细胞对2型糖尿病大鼠的治疗作用及其机制。方法构建2型糖尿病大鼠模型,随机分为干细胞治疗组(MSC组,10只)和糖尿病组(DM组,10只),同时设置正常对照组(N组,10只)。对MSC组的实验鼠进行人脐带间充质干细胞(UC-MSCs)(3×10~6重悬于0.5 ml PBS)尾静脉输注治疗;N组和DM组尾静脉输注等体积PBS,每两周输注1次,共输注4次。治疗4次后,每组随机抽取3只大鼠尾静脉输注CM-Dil染料标记的UC-MSCs,72 h后处死,应用激光共聚焦显微镜检测UC-MSCs在各脏器的分布情况。结果输注UC-MSCs 4次后,DM组血糖维持在28.2±2.9 mmol/L,MSC组血糖水平维持在23.9±3.7 mmol/L,明显低于DM组;MSC组糖耐量水平在各时间点均优于DM组;N组平均体质量约为695g,DM组平均体质量约为582 g,MSC组平均体质量约为599 g,消瘦状态较DM组有所改善;DM组肾小球硬化率为46%,MSC组为16%,多次输注UC-MSCs能有效减轻糖尿病大鼠肾小球硬化程度,此外MSC组脂肪肝程度及胰腺的病理状态与DM组相比均有所改善。CM-Dil阳性UC-MSCs计数结果显示:UC-MSCs经尾静脉输注72 h后主要归巢至脾,且三组脾中归巢干细胞数目无统计学差异(P> 0.05);肾、肝中仅有少量干细胞归巢,其中DM组的归巢干细胞数目明显多于N组和MSC组(P <0.05);三组的胰腺组织中均未观察到CM-Dil阳性细胞。结论多次输注人脐带间充质干细胞对2型糖尿病大鼠有明确的治疗作用,干细胞归巢到肝、肾、胰腺的数目十分有限,大量干细胞归巢于脾。

Objective To investigate the therapeutic effects of multiple intravenous infusions of umbilical cord derived mesenchymal stem cells(UC-MSCs)in type 2 diabetic rats and explore the possible mechanisms of stem cells in the treatment of type 2 diabetes(T2D).Methods The T2D rats were randomly divided into two groups,the stem cells treatment group(MSC group,n=10)and the diabetic group(DM group,n=10),with a control group(N group)including 10 healthy rats.Rats in MSC group were treated with 3×10^6 UC-MSCs suspended in 0.5 ml of phosphate-buffered saline(PBS)through the tail vein.Rats in N group and DM group were infused with the same amount of PBS via the tail vein.Infusion was performed every two weeks,and a total of four infusions were administered.After 4 times of treatment,3 rats were randomly selected from each group for intravenous infusion of CM-Dil dye labeled UC-MSCs.After 72 hours,these animals were sacrificed and the distribution of CM-Dil-labeled UC-MSCs in various organs was explored by laser scanning confocal microscope.Results After four times of infusion of UC-MSCs,the blood glucose of MSC group maintained at 23.9±3.7 mmol/L,which was significantly lower than that of DM group(28.2±2.9 mmol/L).The glucose tolerance level of MSC group was superior to that of group DM at each time point.The average weight of N group was about 695 g,significantly higher than 582 g in DM group,and 599 g in MSC group.While MSC group was significantly improved in weight loss compared to DM group.Compared to DM group(46%),the glomerular sclerosis rate of group MSC was 16%,indicating that multiple infusions of UC-MSCs could effectively reduce the degree of glomerular sclerosis in diabetic rats.In addition,the degree of fatty liver and the pathological state of pancreas in MSC group were better than those in DM group.The results of counting CM-Dil positive UC-MSCs showed that UC-MSCs were mainly found in the spleen at 72 hours after infusion,and there was no significant difference in the number of homing stem cells between the three groups(all P>0.05).Only few stem cells were found in the kidney and liver,but the number of stem cells in DM group was greater than those in N group and MSC group(all P<0.05).No CM-Dil positive cell was found in the pancreatic tissue in the three groups.Conclusion Multiple infusions of UC-MSCs has obvious therapeutic effects on type 2 diabetic rats.The amounts of UC-MSCs homing to liver,kidney and pancreas are rare,while a large number of stem cells are detected in the spleen.