Experimental Study On Induced Differentiation Of Rat Bone Marrow Stromal Stem Cells Into Insulin-Producing Cells

Objective:Pancreatic islets transplantation is the most promising way to cure type I diabetes. But the lack of donor and immunological rejection hamper its use in wide range. Bone marrow stem cells (BMSCs) can be easily gotten. They can reproduce and differentiate into a large number of functional cells in certain conditions. Thus BMSCs transplantation is important in the treatment of diabetes. The studies at present are to investigate the best condition for differentiating BMSCs into insulin-producing cells and its mechanism and to screen for the optimal way for BMSCs transplantation in the treatment of diabetes.Methods:Whole bone marrow adherence method was used for BMSCs isolation and growth characteristics of BMSCs were observed. Part cells were used to induced differentiation into the insulin-secreting cells by adding the Pancreatic extract, niacinamide, Exendin-4 and glucose with varying concentrations into the culture medium. The morphological changes of BMSCs were observed. The insulin-secreting cells was identified by Dithizone (DTZ) staining and levels of insulin and C-peptide in the supernants was detected by radio immunoassay (RIA).The diabetes model in mice were prepared with Streptozotocin (STZ). BMSCs labelled with BrdU were transplanted by the way of injection of caudal vein and renal capsule and pancreas parenchyma. The levels of serum glucose, insulin and C-peptide were examined by biochemistry and radio immunoassay (RIA); The BrdU positive cells in pancreas were detected by Immunohistochemistry.Results:(1) BMSCs tend to aggregate with the inducers of niacinamide, Exendin-4 and high glucose in the culture medium. BMSCs induced with high glucose had an easier tendency to aggregate compared with that in low glucose medium. After pancreatic extract from the newborn mice was added to culture medium with low or high glucose, BMSCs are hardly able to aggregate and tend to die. (2)The majority of cell colonies were stained brownish red while no positive cells were found in the control group. (3)The cells induced by the niacinamide, Exendin-4 could secret insulin and C-peptide after the stimulation with low-glucose and high-glucose, but cells couldn't do that in the control group. (4) The diabetes model was successfully established by peritoneal injection of STZ. (5) The serum glucose levels were significantly lower in the three groups receiving BMSCs transplantation than that of the diabetes control group (P<0.05) especially in the mice receiving BMSCs injection in the pancreas; The levels of insulin and C-peptide were significantly increased in caudal vein group, pancreas parenchyma transplation and renal encyst group than that of the diabetes control group (P<0.05), especially in the group receiving BMSCs injection in the pancreas.(6)The BrdU positive cells in pancreas could be seen in the mice with BMSCs transplantion by caudal vein and in the pancreas. But no BrdU positive cells in pancreas were observed in the mice by kidney capsule, however, the BrdU positive cells could be just found in the kidney.Conclusion:(1) BMSCs could be diffentiated into insulin-secreting cells with the induction of niacinamide and Exendin-4, and a better inducing effect in high glucose culture medium than the culture medium with low glucose. (2) The three way of BMSCs injections by caudial vein, renal capsule and pancreas parenchyma could play the role in curing the diabetes. The effectiveness of BMSCs transplantation is much better than others, but the way by caudial vein is much safe and easy.