ABSTRACT
BACKGROUND:In previous studies,the human umbilical cord mesenchymal stem cells (hUC-MSCs) have been successfully differentiated into islet-like cells in vitro,and insulin expressions have been found.OBJECTIVE:To compare the therapeutic effects of different induced stages of islet-like cells differentiated from hUC-MSCs in a diabetic rat in vivo,so as to find the most suitable induced time in vitro and provide a theoretical basis for clinical treatment of diabetes mellitus.METHODS:Passage 3 hUC-MSCs were differentiated into islet-like cells after 7,14,21,28 days of oriented induction.Eighty male healthy Wistar rats,clean grade,were used in the study.Except eight rats in normal control group,all the rats were injected with streptozotocin at a dose of 70 mg/kg to establish diabetic models.The rats at 10 days after successful modeling were randomly divided into model control group,non-induced group,7-day induction group,14-day induction group,21-day induction group and 28-day induction group.Rats in the normal control group and model control group were given 2 mL of culture medium without any cells and rats in the other groups were implanted withcorresponding cell suspension (2x106 cells) via tail vein for two sessions with an interval of 2 weeks.The blood glucose level,body mass and serum insulin level were detected during the treatment process.The rats were executed to observe the structure changes of each organ at 4 weeks after the second cell transplantation.RESULTS AND CONCLUSION:(1) Compared with the model control group,the body mass and the serum insulin level significantly increased and the blood glucose levels significantly decreased in all the transplantation groups (P ＜ 0.05),and the therapeutic effect was best in the 28-day induction group.(2) Compared with the model control group and normal control group,the frozen sections in all the transplantation groups showed that the morphological structures of the liver and kidney were clear with no abnormal changes,such as necrosis and fibrosis,after transplantation.These experimental results show that it is relatively safe and effective to transplant the different induced stages of islet-like cells induced by hUC-MSCs in the treatment of diabetes mellitus,and the therapeutic effect of islet-like cells at 28 days of in vitro induction is most obvious.