Isolation and characterization in vitro and in vivo of pancreatic islets from NOD mice / 中国实验动物学报

Objective This study was conducted to establish a stable and highly efficient method for isolation and purification of pancreatic islets from NOD mice and to evaluate their characteristics in vitro and in vivo. Methods The is-lets were isolated from mouse pancreas using modified collagenase digestion and Ficoll density gradient centrifugation. The endocrine secretory function was assessed by insulin secretion in either low or high dose glucose stimulation. To evaluate the function of the graft,body weight and blood glucose were monitored,and IVGTT was performed. In addition,to assess sur-vival of the implanted islets,Pathology using HE staining and insulin immunostaining of the graft were performed. Results The average islet yield was 116 ± 12 islets/pancreas and purity was higher than 90%. Compared with islets from Kunming mice,the islets isolated from NOD mice were poorly responsive to glucose challenge. Blood glucose levels and body weight changes of the islet-transplanted diabetic mice were significantly improved compared with the sham-operated mice. In addi-tion,blood glucose levels in vivo after an IVGTT also significantly improved. However,these improvements were only main-tained for 2 weeks. Furthermore,HE staining and immunostaining assays demonstrated that there were insulin-positive cell clusters and lymphocyte infiltration in the graft-bearing kidney. Conclusions A large number of quality islets can be isola-ted and purified from NOD mice by using the modified mouse islet isolation method, which can be used to develop thera-peutic strategies to protect transplanted islets from rejection and autoimmune attack.

MR experiments study on the brain of cynomolgus of diabetic models / 中国医学影像技术

Objective To investigate the value of MRI and~1H-MRS in diagnosis of early stage of diabetic encephalopathy by detecting regional metabolite in cynomolgus diabetes models. Methods Five pathogen-free male adolescent cynomolgus were made type 1 diabetes mellitus models (T1DM) by intravenous injection of streptozotocin (STZ) (100 mg/kg), and the reliability and stability of the modes were assessed with long term follow-up of blood glucose and intravenous glucose tolerance tests. MRI and ~1H-MRS were performed to evaluate the volume, signal intensity and metabolic ratios of NAA/Cr, mI/Cr and Cho/Cr at hippocampus, lateral temporal lobe and occipital lobe 3 years after model establishment. Cortisol in serum was detected with immunoradiometric assay. In addition, 5 normal adult cynomolgus monkeys were selected in the control group and accepted the same examination above. Results ①Intravenous administration of STZ could made stable T1DM monkey model. ②Only mI/Cr ratio increased at hippocampus of diabetic monkeys compared to the control group (P<0.05). ③There was no statistical difference of cortisol in serum between the diabetic group and the control group (P＞0.05). Conclusion ~1H-MRS may detect the metabolic changes of the hippocampus in STZ-induced diabetic adolescent cynomolgus monkeys and may contributes to the early diagnosis of diabetic encephalopathy.