Islet transplantation has the potential to restore normoglycemia and prevent the development of diabetic complications such as retinopathy, nephropathy and neuropathy, and could therefore ve a valuable treatment for diabetic patients. The scarcity of available islets is an obstacle for clinically successful islet transplantation. To resolve the problems, we have examined the two methods, islet transplantation with extracellular matrix1 and in vivo expansion of islets with electrically- transfection of growth factors.
Animals ; Diabetes Mellitus/surgery/*therapy ; Fibronectins/therapeutic use ; Hepatocyte Growth Factor/genetics ; Islets of Langerhans/drug effects/*physiopathology ; *Islets of Langerhans Transplantation ; Male ; Rats ; Rats, Wistar ; *Regeneration ; Transfection

OBJECTIVETo obtain massive human pancreatic islets with modified techniques and evaluation of the islets for the clinical allo-transplantation to treat type I and II diabetes.

METHODS28 consecutive adult human pancreata were isolated with modified automated techniques. Islets were purified using continuous density gradient. The islet yield was counted with international standard known as islet equivalent (IEQ). The function of the isolated islets was evaluated by measuring DNA/insulin ratio, static glucose stimulating test in vitro and transplanting the islets into diabetic nude mice in vivo followed by abdominal glucose tolerance test and C peptide measurement.

RESULTSThe yield of 28 consecutive human pancreata isolations ranged from 5 000 to 1 030 000 IEQs/pancreas with the average of 291 635 IEQs/pancreas. The first 13 isolations yielded 49 123 IEQs/pancreas, 846 IEQs/g and, purity 87% in average. The remained 15 isolations after the modifications yielded 501 813 IEQs/pancreas, 7 003 IEQs/g and purity 89% in average. The results of in vitro SGS showed good response to the different glucose concentration. 34 diabetic nude mice were transplanted under the renal capsule with the freshly isolated islets. 29 out of 34 diabetic mice obtained normoglycemia within 12 hours and the glucose tolerance tests were near normal. Serum C peptide level of transplanted mice is close to that of the control group.

CONCLUSIONSMassive human islets can be isolated with the modified techniques. Quality assessment of these islets both in vitro and in vivo has indicated that these high quality human islets could be used for the clinical allogeneic islet transplantation.

Adult ; Animals ; Cell Separation ; methods ; Diabetes Mellitus, Experimental ; surgery ; Glucose ; Humans ; In Vitro Techniques ; Islets of Langerhans ; cytology ; drug effects ; physiology ; Islets of Langerhans Transplantation ; Mice ; Mice, Nude ; Transplantation, Heterologous

OBJECTIVETo explore the effect of Jiangtang Xiaozhi capsule (JXC) on morphological changes of islets and liver at rat model of type 2 diabetic mellitus and provide the experimental basis for the clinical therapy of type 2 diabetic mellitus.

METHODWister rats were fed on a diet enriched in fat and glucose to induce insulin resistan, the rats were injected intrapertoneally with a low-dose streptozotocin (STZ) twice (25 mg x kg(-1)) to induce hyperglycemia, so the successful rat model of type 2 diabetes were established. The experimental rats were divided into model group, high dose JXC group, middle dose JXC group, low dose JXC group, Erjiashuanggua group, Jinqijiangtang group and normal control group. After all the treatment groups received their own medicine for two months, all the rats were sacrificed and morphological examination on their islets and livers were performed.

RESULTFatty liver in various degrees was seen in the model group and all the treatment groups, but the liver steatosis in middle and low dose JXC groups was significantly milder than that in model group (P < 0.05). Islets in the high dose JXC group were significantly more than that in the model group (P < 0.05).

CONCLUSIONJXC can improve significantly the pathological change in islets and liver steatosis at rat model of type 2 diabetic mellitus.

Animals ; Diabetes Mellitus, Experimental ; drug therapy ; pathology ; Drugs, Chinese Herbal ; pharmacology ; Female ; Islets of Langerhans ; drug effects ; pathology ; Liver ; drug effects ; pathology ; Male ; Microscopy ; Rats ; Rats, Wistar

BACKGROUNDImproving islet graft revascularization has become a crucial task for prolonging islet graft survival. Endothelial cells (ECs) are the basis of new microvessels in an isolated islet, and EC coating has been demonstrated to improve the vascularization and survival of an islet. However, the traditional method of EC coating of islets has low efficiency in vitro. This study was conducted to evaluate the effect of a polyglycolic acid (PGA) scaffold on the efficiency of islet coating by ECs and the angiogenesis in the coated islet graft.

METHODSA PGA fibrous scaffold was used for EC coating of islet culture and was evaluated for its efficiency of EC coating on islets and islet graft angiogenesis.

RESULTSIn in vitro experiments, we found that apoptosis index of ECs-coating islet in PGA group (27% ± 8%) was significantly lower than that in control group (83% ± 20%, P < 0.05) after 7 days culture. Stimulation index was significantly greater in the PGA group than in the control group at day 7 after ECs-coating (2.07 ± 0.31 vs. 1.80 ± 0.23, P < 0.05). vascular endothelial growth factor (VEGF) level in the PGA group was significantly higher than the coating in the control group after 7 days culture (52.10 ± 13.50 ng/ml vs. 16.30 ± 8.10 ng/ml, P < 0.05). Because of a tight, circumvallated, adhesive and three-dimensional growth microenvironment, islet cultured in a PGA scaffold had higher coating efficiency showing stronger staining intensity of enzyme than those in the control group after 14 days of culture following ECs-coating. For in vivo study, PGA scaffold significantly prolonged the average survival time of EC-coated islet graft after transplantation compared with control group (15.30 ± 5.60 days vs. 8.30 ± 2.45 days, P < 0.05). The angiogenesis and area of survived grafts were more in the PGA group compared with the control group by measuring the mean microvessel density (8.60 ± 1.21/mm2 vs. 5.20 ± 0.87/mm2, P < 0.05). In addition, expression of VEGF and tyrosin-protein kinase receptor (Tie-2) gene increased in PGA scaffold group than that in control group by real-time reverse transcription-polymerase chain reaction analysis.

CONCLUSIONSThese results demonstrate that the efficiency of EC coating of islets was successfully increased by culturing ECs on a PGA scaffold. This method enhances the function, survival, and vascularization of isolated islets in vitro and in vivo.

Animals ; Apoptosis ; drug effects ; Endothelial Cells ; drug effects ; Enzyme-Linked Immunosorbent Assay ; Graft Survival ; drug effects ; Insulin ; metabolism ; Islets of Langerhans ; drug effects ; Islets of Langerhans Transplantation ; methods ; Neovascularization, Physiologic ; drug effects ; Polyglycolic Acid ; chemistry ; pharmacology ; Rats ; Rats, Sprague-Dawley ; Rats, Wistar ; Tissue Scaffolds ; chemistry

OBJECTIVETo study the effects of a self-formulated blood glucose-adjusting recipe on blood glucose and pathology of the pancreas in diabetic mice.

METHODSDiabetes mellitus (DM) was induced in mice by injection of alloxan through the caudal vein. The blood glucose-adjusting recipe was administered in the mice at the doses of 20, 10 and 5 g/kg for 21 days, after which blood glucose was determined and the sugar tolerance was evaluated, and the pancreas and islet pathologies were examined microscopically.

RESULTSThe blood glucose-adjusting recipe at 20 g/kg significantly lowered the fast blood glucose in the mice, and at 20 and 10 g/kg, the recipe significantly lowered the blood glucose 2 h after glucose administration and increased the sugar tolerance. The pathological damage in the diabetic mice was alleviated after treatment with the recipe.

CONCLUSIONSThe blood glucose-adjusting recipe has a good effect in stabilizing blood glucose in mice.

Animals ; Blood Glucose ; drug effects ; Diabetes Mellitus, Experimental ; blood ; drug therapy ; pathology ; Drugs, Chinese Herbal ; therapeutic use ; Islets of Langerhans ; pathology ; Mice ; Phytotherapy

Nonspecific inflammatory response is the major cause for failure of islet grafts at the early phase of intraportal islet transplantation (IPIT). Bilirubin, a natural product of heme catabolism, has displayed anti-oxidative and anti-inflammatory activities. The present study has demonstrated that bilirubin protected islet grafts by inhibiting nonspecific inflammatory response in a syngeneic rat model of IPIT. The inflammation-induced cell injury was mimicked by exposing cultured rat insulinoma INS-1 cells to cytokines (IL-1beta, TNF-alpha and IFN-gamma) in in vitro assays. At appropriate lower concentrations, bilirubin significantly attenuated the reduced cell viability and enhanced cell apoptosis induced by cytokines, and protected the insulin secretory function of INS-1 cells. Diabetic inbred male Lewis rats induced by streptozotocin underwent IPIT at different islet equivalents (IEQs) (optimal dose of 1000, and suboptimal doses of 750 or 500), and bilirubin was administered to the recipients every 12 h, starting from one day before transplantation until 5 days after transplantation. Administration of bilirubin improved glucose control and enhanced glucose tolerance in diabetic recipients, and reduced the serum levels of inflammatory mediators including IL-1beta, TNF-alpha, soluble intercellular adhesion molecule 1, monocyte chemoattractant protein-1 and NO, and inhibited the infiltration of Kupffer cells into the islet grafts, and restored insulin-producing ability of transplanted islets.
Animals ; Apoptosis/drug effects/immunology ; Bilirubin/*administration & dosage/pharmacology ; Cell Line, Tumor ; Cytokines/immunology/metabolism ; Diabetes Mellitus, Experimental/*drug therapy/*immunology ; Inflammation ; Inflammation Mediators/immunology/metabolism ; Islets of Langerhans/drug effects/*immunology/injuries/pathology ; *Islets of Langerhans Transplantation ; Male ; Oxidative Stress/drug effects/immunology ; Rats ; Rats, Inbred Lew ; Transplantation, I

OBJECTIVETo evaluate the insulin and leptin resistance of curcumin on simplicity obesity rats.

METHODSAll 50 SPF grade healthy Sprague-Dawley male initial weaning rats were used for two groups in stratified sampling by weight: 30 in treated group and 20 in control group. They were assigned to the following treatment for 8 weeks: the treated group was fed with high-fat food and the control group was fed with normal food. Eight weeks later, adiposity model rats were prepared. Groups: adiposity model rats were divided into 3 groups: model + low curcumin (1.25 g/kg), model + high curcumin (5.00 g/kg) and a model group. In addition, there also had a normal control and a control + high curcumin (5.00 g/kg) group. Ten rats in every group and all given ground feed. After intragastric administration in different doses of curcumin 4 weeks, the effects and pathological changes were observed by the blood sugar, insulin, leptin and TNF-alpha, pathology and transmission electron microscope of pancreatic gland.

RESULTSGiven 4 weeks the different dose of curcumin on the simplicity obesity rats, the significant diminished weight (435.0 +/- 37.6) g and content of lipocyte (4.78 +/- 1.87) g as compared with the obesity model control (492.3 +/- 14.8) g and (8.94 +/- 1.88) g (t values were 4.484 and 4.961 respectively, P < 0.01), level of blood sugar (4.50 +/- 0.09) mmol/L, insulin (7.43 +/- 0.65) mmol/L, leptin (3.40 +/- 0.39) mmol/L and TNF-alpha (2.42 +/- 0.19) ng/ml were significantly decreased than those of adiposity model rats (4.94 +/- 0.12) mmol/L, (9.30 +/- 0.21) mmol/L, (4.40 +/- 0.23) mmol/L and (2.86 +/- 0.49) ng/ml (t values were 8.297, 7.743, 6.247 and 2.368 respectively, P < 0.05), and there was no significant difference with the control group (4.30 +/- 0.14) mmol/L on the level of blood sugar (t = 0.399, P > 0.05). There were a lot of secretory granules with large sphere volume in beta cells of pancreatic island found by transmission electron microscope, and these secretory granules had a higher electron density than those in non-disposed groups.

CONCLUSIONBy diminishing the sediment of fat, relaxing the lymphatic return, and refraining the apoptosis of beta cells, the curcumin might significantly decrease the level of insulin resistance and leptin resistance caused by the high fat diet.

Animals ; Apoptosis ; Curcumin ; pharmacology ; Disease Models, Animal ; Insulin ; metabolism ; pharmacology ; Insulin Resistance ; Islets of Langerhans ; drug effects ; Leptin ; metabolism ; pharmacology ; Male ; Obesity ; metabolism ; Rats ; Rats, Sprague-Dawley

OBJECTIVETo investigate the effects of the chemical constituents of the whole herbs of Crossostephium chinense on insulin secretion in rat islets.

METHODIslets were isolated from rat pancreata, cultured in vitro, and measured by color signals of dithizone stained digestion solution for detection of pancreatic islets. The morphological observation of islets was carried out by inverted microscope. The effects of test compounds, scopoletin (1), scopolin (2), tanacetin (3), quercetagetin-3,6,7-trimethylether (4) and 5-O-methyl-myo-inositol (5) isolated from the whole herbs of C. chinense, on the insulin secreting level from islets were compared with those of glybenclamide as a positive control substances, and the difference in insulin secreting level from islets between the presence and absence of test compounds was assayed.

RESULTThere was no difference in basal insulin secretion before and after 2 h incubation period of rat islets. The islets treated with quercetagetin-3,6,7-trimethylether have about 2-fold higher insulin secreting level (P < 0.01) compared a normal control group. The islets treated with 5-O-methyl-myo-inositol have about 1.5-fold higher insulin secreting level (P < 0.05) compared to a normal control group. Whereas the islets treated with scopoletin show about 1.9-fold lower basal insulin secreting level (P < 0.05) than a normal control group.

CONCLUSIONIn this paper the developed cultivation method of isolated pancreatic islets from rat can be used as a kind of islet-based drug screening model for diabetes mellitus in vitro. Quercetagetin-3,6,7-trimethylether and 5-O-methyl-myo-inositol could enhance rat islet insulin secretion and further in vivo studies are needed to clarify the nature of such an observation. However, scopletin suppress rat islet insulin secretion.

Animals ; Asteraceae ; chemistry ; Drugs, Chinese Herbal ; chemistry ; pharmacology ; In Vitro Techniques ; Insulin ; secretion ; Islets of Langerhans ; drug effects ; secretion ; Male ; Rats ; Rats, Sprague-Dawley

OBJECTIVETo investigate the role of insulin receptor substrate 2 (IRS2) and Bax on mouse islet cell apoptosis in the presence of high glucose in vitro.

METHODSThe pancreatic islet cells were isolated from Kunming mice and divided into 6 groups (G1-G6 groups) for a 72-h culture in the media containing different concentrations of glucose (5.6, 7.8, 11.1, 16.7, 22.2, and 27.6 mmol/L, respectively). Insulin secretion by the cells was evaluated by radioimmunoassay, and the expressions of IRS2 and Bax were detected using immunocytochemistry and immunofluorescence assay, respectively. Hoechst33342 staining was employed to observe the cell apoptosis.

RESULTSExposure to 5.6-11.1 mmol/L glucose resulted in increased insulin secretion and progressive elevation of IRS2 and Bax expression, whereas the cell apoptosis underwent no obvious changes. In the presence of glucose above 16.7 mmol/L, the percentages of apoptotic islet cells increased with glucose concentration, but insulin secretion and IRS2 expression decreased; Bax expression significantly increased in the presence of high-concentration glucose.

CONCLUSIONProlonged exposure of mouse islet cells to high glucose induces apoptosis and impairs insulin secretion of the cells. Decreased IRS2 expression and increased Bax expression may play an important role in the glucotoxicity in mouse islet cells.

Animals ; Apoptosis ; Cells, Cultured ; Glucose ; pharmacology ; Insulin Receptor Substrate Proteins ; metabolism ; Islets of Langerhans ; drug effects ; metabolism ; Mice ; Mice, Inbred Strains ; bcl-2-Associated X Protein ; metabolism

AIMTo isolate, culture pancreatic progenitor cells derived from islets of newborn rats, and to observe the effect of GLP-1 (7-36) NH2 on islet progenitor differentiation.

METHODSIslets were isolated purified, islet progenitor cells were isolated and proliferated in the modified RPMI-1640 medium supplemented with 20 microg/L bFGF and 20 microg/L EGF, then were differentiated with 20 nmol/L GLP-1 (7-36) NH2. The properties of islet progenitor cells were identified primarily by hybridization in situ, immunocytochemistry, dithizone (DTZ)-staining, and radioimmunoassay before and after differentiation.

RESULTSIslet progenitor cells did not express PDX-1, insulin and somatostatin, but nestin. After differentiation, a portion of cells expressing PDX-1, insulin mRNA, insulin, somatostatin, and nestin, islet-like cell clusters (ICCs) were formed, DTZ-stained cells were in peripheral region of it. Insulin release was markedly greater in media harvested after differentiation of 3 weeks.

CONCLUSIONA kind of progenitor cells exists in pancreatic islet of newborn SD rats, could be expanded continuously. GLP-1 (7-36) NH2 could differentiate pancreatic islet-derived progenitor cells to form ICCs capable of insulin secretion.

Animals ; Animals, Newborn ; Cell Culture Techniques ; Cell Differentiation ; drug effects ; Cell Separation ; Cells, Cultured ; Glucagon-Like Peptide 1 ; pharmacology ; Islets of Langerhans ; cytology ; Male ; Rats ; Stem Cells ; cytology