Objective To investigate the effect of constitutively active Akt1 gene on rat engrafted islets in apoptosis and revascularization, and to explore potential method of gene therapy in the islet transplantation. Methods Rat islet which was transfected constitutively actived Akt1 gene via adenovirus vector using MOI=500. Thirty-six streptozotocin induced diabetic Wistar rats were divided into 3 groups complete randomly: Adv-CA-Akt1 group, Adv-LacZ group and simple transplantation group. Blood glucose and insulin were determined after operation. TUNEL was used to detect the apoptotic islet cells. HE and immunohistochemical staining of insulin were used to evaluate the histology of the islet grafts. The microvessel density (MVD) was determined by CD31 immunohistochemical staining. Results The fasting glucose level in Adv-CA-Akt1 group restored to normal 2 days after transplantation. However, in Adv-LacZ group and simple transplantation group, it reduced but still kept being hyperglycemia. And the serum insulin level was higher than other two groups ( P ＜ 0.05). Compared to simple transplantation group and Adv-LacZ group, apoptotic rate decreased 25% in Adv-CA-Akt1 group, a large number of islet grafts were seen under the capsule of the kidney, which were positively stained by insulin antibody. In the other two groups, the islet groups mass were lighter, and few positively stained by insulin antibody. MVD showed lighter positive endothelial cells stained by CD31 antibody in the other two groups than Adv-CA-Akt1 group ( P ＜ 0.05). Conclusion Constitutively activate Akt1 gene can prolong graft survival during early posttransplant period, and can accelerate the revascularization of islet grafts effectively.
Objective To introduce a new method of tissue engineering research by transplanting vessels to tissue engineering chamber (vascularized tissue engineering chamber) in vivo, and to review the progress of research in vascularized tissue engineering chamber. Methods The l iterature concerning all kinds of tissue engineering research in chamber was reviewed, analysed, and summarized. Results The use of vascularized tissue engineering chamber allowed generation of vascularized adipose tissue, cardiac tissue, and so on. The most common tissue engineering chamber models were arterio-venous loop model and inferior epigastric artery model. Conclusion The method of tissue engineering research by using vascularized tissue engineering chamber has a potential cl inical value and provides a promising future.
Objective To investigate the anti-rejection effect and the mechanism of triptolide （TPT） on islet allo- grafts in a murine model. Methods BALB/c mice were used as islet donor. C57BL/6 mice were rendered diabetic by streptozotocin （STZ） injection， and transplanted with islets under the left kidney capsule. The recipients were randomly （method of random digits table） divided into three groups （n=8）. The mice in the treatment groups were injected intrap-eritoneally with TPT at 50 μg/kg （low-dose TPT group， L-TPT group） or 100 μg/kg （high-dose TPT group， H-TPT group） daily in the first 5 days and then on alternate days until 14 days；while the mice in control group were given vehicles （1% tween 80）. Blood glucose after operation were monitored. The grafts were defined as rejection when two consecutive reading of blood glucose＞20 mmol/L. The left kidney of three recipients in each group were resected for pathological examination. The proportion of CD4＋CD25＋Foxp3＋ regulatory T cells in spleen tissues were tested by flow cytometry. Results The median survival time of islet allografts from the control group， L-TPT group， and H-TPT group were 12.6 days （9-16 days）， 21.4 days （14-27 days） ， and 27.6 days （19-34 days）， respectivly. The percentageof CD4＋CD25＋Foxp3＋regulatory T cells in spleen tissues of three groups were （5.2±0.6）%， （12.0±1.3）%， and（15.7±1.8）%， respectivly. Compared with control group， the median survival time of islet transplantation in mice exte-nded and the proportion of CD4＋CD25＋Foxp3＋ regulatory T cells in spleen tissues increased （P＜0.05）. Conclusions TPT could increase the percentage of CD4＋CD25＋Foxp3＋ regulatory T cells， reduce the rejection after islet transplanta-tion， and prolong the survival time of islet transplantation in mice. The immunosuppressive effect of TPT shows a dose-dependent.
Objective To summarize and analyze the different modality on molecular imaging of tracking and monitoring for islet transplantation．Methods The current domestic and foreign reports on molecular imaging of islet transplantation were reviewed．Results Magnetic resonance imaging has high sensitivity，high spatial resolution，no ionizing radiation，is clinically applicable，and could be used of real-time MR-guided injections，but can’t discriminate between liver and dead cells，difficult to do in patients with liver iron overload．Nuclear molecular imaging only displays liver cells generate signal，is clinically applicable，but disadvantage is genetic manipulation，ionizing radiation，no anatomical information，low spatial resolution．The advantage of in vivo optical imaging is only liver cells generate signal，widely available，no ionizing radiation，and the disadvantage is genetic manipulation，not clinically applicable，low spatial resolution．Conclusions Islet imaging using magnetic resonance，nuclear molecular imaging，in vivo optical imaging，or multimodal imaging of microencapsulated islets may provide us with a direct means to interrogate islet cell distribution，survival，and function．Multimodal imaging of microencapsulated islets may be best way for tracking and monitoring in the future．
Objective To investigate the effect of inducible nitric oxide synthase (iNOS) inhibitor aminoguanidine on pancreas islets cultured with cytokines TNF-α and IL-1β in rats. Methods Islets isolated from Wistar rats were purified and cultured. According to whether cytokines TNF-α, IL-1β and aminoguanidine were added into the medium respectively or not, islets were divided into 4 groups: cultured with islet only was taken as blank control group, cultured with TNF-α+IL-1β as cytokine group, cultured with aminoguanidine as aminoguanidine group, and cultured with TNF-α+IL-1β and aminoguanidine as aminoguanidine+cytokine group. NO level in culture medium and iNOS activity in islets tissue (Test Kit), apoptosis (TUNEL method) and viability of islets cell (acridine orange/ethidium bromide stain), and the function of islets (insulin release test) were measured. Results Compared with blank control group, the activity of iNOS in islet tissue and level of NO in culture medium increased, and the mass mortality and apoptosis appeared in islet cells, while insulin secretion decreased in cytokine group (P＜0.01). Compared with cytokine group, the activity of iNOS 〔（3.17±0.51） U/ml vs. （38.93±4.72） U/ml〕 and level of NO 〔（50.5±10.4） μmol/L vs. （313.0±35.4） μmol/L〕 decreased, the survival 〔（72.73±3.14）% vs. （57.07±5.07）%〕 increased and the apoptosis rate 〔（20.11±8.48）% vs. （41.17±6.87）%〕 decreased, the insulin secretion (secretion index: 3.50±0.27 vs. 1.96±0.19) improved； There were all significant differences in 2 groups (P＜0.01). Conclusion The iNOS inhibitor aminoguanidine could prevent the islet from the damage of iNOS/NO, alleviate the impairment of cytokines to islets, and ameliorate the survival and function of islets.
【Abstract】ObjectiveTo develop a method of adult porcine pancreatic islet isolation.MethodsThe tails of adult porcine pancreas were perfused through the pancreatic duct with 0.1% cold collagenase(type Ⅺ) and incubated at 38.5 ℃.The digested tissue was dispersed in 4 ℃ Hanks balanced salt solution(HBSS).The tissue suspensions were filtered through a 600 μm mesh.The residual tissue was resuspended in cold HBSS,and put in the Ricordi’s chamber and shaken for 5 minutes,then filtered again.The isolated islets were divided into three groups: control group(n=14),Pefabloc(trypsin inhibitor,n=8) group and FOY(trypsin inhibitor,n=5) group.The collagenase solution of the Pefabloc and FOY group was supplemented with 1.0 mmol/L Pefabloc and FOY respectively. ResultsThe islet yields of the Pefabloc group and FOY group 〔(11 848±3 530) islet/g pancreas and (14 496±3 693) islet/g pancreas〕 were significantly higher than that of the control group 〔(8 505±3 349) islet/g pancreas〕,P＜0.05.The activity of pancreatic protein enzyme in digestive fluid after digestion in control group was higher than the activity of pancreatic duct before injection and Pefabloc group(P＜0.01),which the control group, pancreatic duct before injection and Pefabloc group were (114.7±50.0) BAEEU,(4.0±1.8) BAEEU and (5.5±2.7) BAEEU,respectively.The pancreatic duct before injection and Pefabloc group showed no significant difference in statistics. In control group,when the harvest of islet was more than 8 000/g,the activity of pancreatic protoin enzyme was less than that with the harvest of islet below 8 000/g 〔(78.3±26.7) BAEEU vs (137.5±48.4) BAEEU,P＜0.05〕.Islet after purification in control group,Pefabloc group and FOY group showed good insulin secretion ability for different concentration of glucose.ConclusionA higher porcine pancreatic islet yield can be obtained by this method of pancreatic islet isolation and prophylactic administration of trypsin inhibitors consistently produce excellent islet yields.
ObjectiveTo explore the endothelial cells from human peripheral blood and islet of rat co-transplantation under the renal capsule of diabetic nude mice to improve the survival and function of transplanted islet. MethodsThe endothelial cells from human peripheral blood(5×105)and freshly isolated rat islet cells were co-transplanted under the renal capsule of diabetic nude mice model, then the fasting blood glucose, body weight, peripheral blood C-peptide level, and intraperitoneal glucose tolerance test(IPGTT) were measured to evaluated the islet graft survival and function. ResultsCompared with the control group, the fasting blood glucose level significantly decreased(P < 0.01), peripheral blood C-peptide level rised(P < 0.01), and body weight increased(P < 0.01) of receptor nude mice in experience group, the IPGTT also improved. ConclusionThe endothelial cells from human peripheral blood and islet of rat co-transplan-tation can obviously improve the survival and function of transplanted islet of nude mice.
Objective To summarize the research progress on the source and selection of donor cells in the field of islet replacement therapy for diabetes mellitus. Methods Domestic and abroad literature concerning islet replacement therapy for diabetes mellitus, as well as donor source and donor selection was reviewed and analyzed thoroughly. Results The shortage of donor supply is still a major obstacle for the widely clinical application of pancreatic islet transplantation (PIT). Currently, in addition to the progress on the allogeneic/autologous donor islet supply, some remarkable achievements have been also attained in the application of xenogeneic islet (from pig donor), as well as islet like cells derived from stem cells and islet cell line, potentially enlarging the source of implantable cells. Conclusion Adequate and suitable donor cell supply is an essential prerequisite for widely clinical application of PIT therapy for type 1 diabetes mellitus (T1DM). Further perfection of organ donation system, together with development of immune-tolerance induction, gene and bioengineering technology etc. will possibly solve the problem of donor cell shortage and provide a basis for clinical application of cellular replacement therapy for T1DM.