ABSTRACT
Objective To investigate the isolation and protective effect of a new islet purification solution (IPS)-Optiprep solution on the islet in mouse models. Methods The digested pancreatic islets were divided into the IPS and UW groups according to the islet volume. The pancreatic islets were isolated by the continuous gradient density centrifugation using IPS-Optiprep or UW-Optiprep solutions. The purification efficiency and isolated islet activity of purification solution were compared between two groups. The diabetic mouse models were successfully induced and randomly assigned into three groups. In the experimental group (n=10), the mice received pancreatic islet transplantation using islets isolated and purified by the IPS-Optiprep solution. In the control group (n=10), the mice underwent pancreatic islet transplantation using islets isolated and purified by the UW-Optiprep solution. In the sham surgery group (n=5), the mice merely underwent surgery without pancreatic islet transplantation. Postoperative blood glucose levels were detected and compared among three groups. The blood glucose levels of intraperitoneal glucose tolerance test at postoperative 21 d were statistically compared between the experimental and control groups. The cost of the preparation of two isolation solutions was also compared. Results Compared with the UW group, the islet equivalent (IEQ), islet purity, recovery rate and islet integrity were significantly higher in the IPS group. Islet morphological observation revealed that the islet membrane was complete and the islet diameter in the IPS group was considerably larger than that in the UW group. The activity of purified islets in the UW group was significantly higher than that in the IPS group [(88±5)% vs. (84±3)%, P<0.01]. Compared with the UW-Optiprep solution, identical in vivo islet function was obtained in the IPS-Optiprep solution.The cost of IPS-Optiprep solution was significantly less than that of the UW-Optiprep solution. Conclusions The new IPS-Optiprep solution yields higher islet isolation efficiency, purification, integrity and recovery rate and significantly reduces the purification cost compared with the UW-Optiprep solution. Nevertheless, IPS-Optiprep solution exerts a less protective effect on the activity of islet cells, which is probably correlated with the high islet integrity and the endotoxin in the IPS-Optiprep solution.
ABSTRACT
Objective To investigate whether pancreatic islet transplantation in combination with bone mesenchymal stem cells (MSC) transplantation can promote the vascularization surrounding the transplant pancreatic islet.Methods The non-obese diabetic (NOD) mice were utilized as the recipients and randomly divided into pancreatic islet transplantation combined with MSC transplantation group (co-transplantation group,n=6),pancreatic islet transplantation group(n=6),MSC transplantation group(n=6) and sham transplantation group (n=3).The variation in blood glucose level and survival rate post-transplantation of NOD mice in each group was observed.The proliferation and apoptosis of the transplant pancreatic islet in the pancreatic islet transplantation group and co-transplantation group at 1,2 and 4 weeks after pancreatic islet transplantation were analyzed by 5-ethynyl-2'-deoxyufidine (EdU) and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL).The vascular density surrounding the transplanted pancreatic islet in the pancreatic islet transplantation group and co-transplantation group at postoperative 2,4 and 8 weeks were observed under light microscope and quantitatively analyzed by histochemical and immunohistochemical staining.Results Both MSC combined with pancreatic islet transplantation and pancreatic islet transplantation significantly improved the blood glucose level and enhanced the survival rate of NOD mouse models after transplantation.In addition,it could accelerate the regeneration of pancreatic islet cells and decrease cell apoptosis.MSC combined with pancreatic islet transplantation significantly enhanced the vascular density surrounding the transplant pancreatic islet compared with pancreatic islet transplantation alone.Conclusions MSC transplantation can accelerate the vascularization surrounding the transplant pancreatic islet,increase the blood supply and protect the function and activity of the transplant pancreatic islet.
ABSTRACT
Objective To investigate the mechanisms of mesenchymal stromal cells (MSCs) in promoting the transplanted islets neovascularization.Methods We performed co-transplantation of allogeneic islet and MSCs into non-obese diabetic (NOD) mice and the lymphocyte chimeric rate was detected by flow cytometry.The MSCs migration,transformation and secretion of cytokines were detected by immunofluorescence.Results In mice of co-combination transplantation of islet with MSCs,donor lymphocytic chimerism in graft was increased.BM-MSCs can migrate to transplanted islet,differentiate into vascular smooth muscle cells,and also secrete vascular endothelial growth factor (VEGF).Conclusions MSCs can migrate to transplanted islet and promote neovascularization.Also,it enhanced allograft immune tolerance of islet grafts via increasing donor lymphocytic chimerism.