Experimental Study On The Treatment Of Different Approaches To Transplant Human Umbilical Cord Mesenchymal Stem Cells Into Rats With Type 1 Diabetes Mellitus

BackgroundType 1 diabetes mellitus(T1DM)is a metabolic disease that involves the progressive destruction of pancreatic ?-cells,ultimately resulting in the loss of insulin production and secretion.Lots of researches indicated that blood glucose levels were decreased after the diabetic rats were transplanted with human umbilical cord mesenchymal stem cells which have potentialities of great proliferation and multi-directional differentiation and receive much concern.Therefore,it is thought to be a new valuable source of beta cells replacement therapy.There are many ways of stem cells transplantation in vivo,which have different effects.However,it is important to choose the right choice of cell transplantation approach in order to reach the appropriate transplant place for stable engraftment and durable survival.While the therapeutic effects of hUCMSCs have been certified generally,its exact hypoglycemic mechanism is still not understood clearly.ObjectiveTo observe the blood glucose levels,plasma insulin levels and morphological changes of pancreas and livers of three ways of human umbilical cord mesenchymal stem cells(hUCMSCs)transplantation including caudal intravenous injection,injection within the liver parenchyma and injection under the pancreas capsule in rats with experimental type 1 diabetes mellitus,detect the expression of human & rat insulin and human & rat pancreatic duodenal homeobox 1(PDX-1)mRNA and MAB1281 in the recipients,pancreas after 4 weeks.While contrasting the therapeutic effects of different transplant pathways,try to initially discuss the possible mechanism of hUCMSCs in treating T1 DM so as to lay afoundation for further studying the explicit therapeutic effect of hUCMSCs for T1 DM.MethodsThe intraperitoneal injection of streptozotocin was used to establish model of experimental type 1 diabetic rats characterized by beta cell destruction.The rats were randomly divided into normal control group,T1 DM model group and hUCMSCs treatment group.The three groups were randomly divided into three subgroups of transplantation respectively,including caudal intravenous injection(NC group,n=6;dC group,n=6;DC group,n=8),injection within the liver parenchyma(NH group,n=6;dH group,n=6;DH group,n=8)and injection under the pancreas capsule(NP group,n=6;dP group,n=6;DP group,n=8).HUCMSCs was administered into hUCMSCs treatment group while normal saline solution was injected into the other two groups.The blood glucose levels of rats were detected weekly in the groups for four weeks.Concentrations of plasma insulin were detected at the end of two and four weeks after transplantation;Hematoxylin-eosin staining and optical microscope were used to observe morphological changes of pancreas and livers;Perform immunohistochemistry in order to investgate the positive staining situation of insulin and mouse anti-human nuclei monoclonal antibody(MAB1281)in pancreas and liver.Image-Pro Plus 6.0 was used for analyzing integrated optic density(IOD)of staining region on rats,pancreatic and hepatic slices in each group;The expression levels of human/rat insulin,human/rat pancreatic duodenal homeobox 1(PDX-1)mRNAs were determined by semi-quantitative reverse transcription polymerase chain reaction(RT-PCR).Data collected was analysed by SPSS 21.0 software.One-way ANOVA and Kruskal-Wallis test were used to compare the difference between groups.P < 0.05 showed the significance of statistical difference.ResultsBlood glucose levels in rats with T1 DM after hUCMSCs transplantation were lowered(P<0.05)while concentrations of plasma insulin were increased significantly(P<0.05).Among the hUCMSCs treated groups,injection under the pancreas capsule is the best.Insulin positive staining area in the group of hUCMSCs injection under the pancreas capsule is larger than the other two hUCMSCs treatment groups and T1 DM model group(all P < 0.05).MAB1281 immunohistochemical staining showed that hUCMSCs colonized in corresponding parts in hUCMSCstransplanted group.Compared with T1 DM model group,the amount of insulin expression in hUCMSCs transplanted group was higher,especially for the group of hUCMSCs injection under the pancreas capsule.No evidence of human insulin and human/rat PDX-1 mRNA expression was seen within pancreas.Conclusions1.HUCMSCs can reduce blood glucose levels and increase concentrations of plasma insulin in type 1 diabetic rats through caudal intravenous injection,injection within the liver parenchyma and injection under the pancreas capsule,and the last pathway gets the best effect.2.HUCMSCs can be transplanted in graft site.It,s impossible that hUCMSCs transdifferentiate into pancreatic islets ? cells directly in type 1 diabetic rats,but it may play the role of hypoglycemic therapy by initiating proliferation and differentiation of pancreatic stem cells.