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

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

OBJECTIVETo investigate the feasibility and benefits of co-culture of cryopreserved islets with small intestinal submucosa (SIS).

METHODSPurified rat islets cryopreserved for one month were divided into SIS group and control group, and after culture in standard islet culture media RPMI1640 for 1 week, the morphology and function of the islets were assessed.

RESULTSThe SIS protects the fragile islets from damage by cryopreservation, and increased the recovery from (60.6-/+3.3)% to (91.7-/+1.8) % (P<0.05). Compared with the control group, incubation of the islets of the SIS group in high-glucose (16.7 mmol/L) solution resulted in significantly enhanced insulin secretion (23.7-/+1.6 vs 12.5-/+1.1 mU/L, P<0.05). When the islets were incubated in high-glucose solution containing theophylline, the calculated stimulation index of SIS group was about 3-fold higher than that of the control group.

CONCLUSIONCo-culture of cryopreserved rat islets with SIS can increase the recovery of islet cells and improve their function.

Animals ; Coculture Techniques ; Cryopreservation ; methods ; Glucose ; pharmacology ; Insulin ; secretion ; Intestinal Mucosa ; cytology ; drug effects ; physiology ; Intestine, Small ; cytology ; drug effects ; physiology ; Islets of Langerhans ; cytology ; drug effects ; physiology ; Male ; Rats ; Rats, Wistar ; Theophylline ; pharmacology

OBJECTIVETo establish an semi-automated effective method for large-scale purification of islet cells from human pancreas.

METHODSHuman pancreas tissue was digested with collagenase P using a semi-automated pancreas-digestion system followed by purification in a HCA-Ficoll continuous gradient using Cobe2991 cell separator. After isolation, the islet cell yield and purity was evaluated with light microscope with DTZ staining, and the islet function assessed by insulin release assay in vitro.

RESULTSThe number of the islets collected from each pancreas averaged 38 6201-/+78 219 islet equivalents (IEQ) before purification, and 231 420-/+28 054 IEQ after the purification with discontinuous gradient centrifugation. From each gram of the pancreatic tissue, 3148-/+317 IEQ were obtained with an average purity of (62.81-/+2.68) %. The purified islets responded well to high-concentration (16.7 mmol/L) glucose stimulation with a 2.53-fold increase of insulin secretion over the basal level (3.3 mmol/l, P<0.001).

CONCLUSIONThe established semi-automated method can be applicable for large-scale purification of fully functional islet cells from human pancreas.

Cell Count ; Cell Separation ; instrumentation ; methods ; Cell Survival ; Glucose ; pharmacology ; Humans ; Insulin ; secretion ; Islets of Langerhans ; cytology ; drug effects ; metabolism ; Reproducibility of Results

OBJECTIVETo study the effects of in vitro inducement on the expression of SF1-G imprinted genes, Kcnq1 and Cdkn1c during the course of differentiation from mouse embryonic stem (ES) cells to islet-like cells.

METHODSMouse ES cells were induced to differentiate into islet-like cells in vitro. The expression of islet specific markers was tested by RT-PCR or immunofluorescence. RT-PCR/RFLP was used to test the imprinted genes parental expression in cells at different stages.

RESULTSIslet specific genes, such as Insulin, Glucagon, Somatostatin, IAPP and Glut2, were expressed in differentiated cells. The proteins of insulin, C-peptide and Somastatin were expressed in the final stage cells. Imprinted gene Kcnq1 and Cdkn1c were biallelicly expressed in islet-like cells.

CONCLUSIONSMouse ES cells can be successfully induced into islet-like cells in vitro. Gene imprinting status of Kcnq1 and Cdkn1c may be changed in differentiated cells (causing loss of imprinting) during the in vitro inducement.

Animals ; Cell Differentiation ; drug effects ; Insulin ; Islets of Langerhans ; cytology ; Mice ; Mouse Embryonic Stem Cells ; Proteins ; Reverse Transcriptase Polymerase Chain Reaction ; Stem Cells

In this study, the rat type 2 diabetes mellitus (T2DM) model was established through tail vein injection with low dose of streptozotocin (STZ) and high fat diet for 8 weeks, and then treated with Jiaotai Pill. The oral glucose tolerance test (OGTT), fasting serum insulin (FINS), free fatty acid(FFA) levels and blood lipid were assayed. HOMA-IR was calculated. Pancreatic pathology was performed. And pancreatic triglyceride (TG) content was examined by the lipid extraction method. Pancreatic islet cell apoptosis were detected by terminal dexynucleotidyl transferase (TdT)-mediated dUTP nick end labeling (TUNEL). According to the results, the model group showed abnormal OGTT, increased FINS, HOMA-IR, FFA, lipid disorder, obvious fat accumulation and significantly increased TG content in pancreatic tissues, and enhanced pancreatic islet cell apoptosis. Compared with the model group, the Jiaotai Pill group displayed improved OGTT, reduced FINS, HOMA-IR, FFA, recovered lipid disorder, decreased fat accumulation and significantly declined TG content in pancreatic tissues, and lowered pancreatic islet cell apoptosis. In summary, Jiaotai pill could effectively treat type 2 diabetes in rats. Its mechanism may be related to the reduction in pancreatic fat accumulation and islet cell apoptosis.
Animals ; Apoptosis ; drug effects ; Diabetes Mellitus, Type 2 ; drug therapy ; metabolism ; physiopathology ; Drugs, Chinese Herbal ; administration & dosage ; Fats ; metabolism ; Glucose Tolerance Test ; Humans ; Islets of Langerhans ; cytology ; drug effects ; Male ; Pancreas ; drug effects ; metabolism ; Rats ; Rats, Wistar

OBJECTIVETo study the effect of heme oxygenase-1(HO-1) on proteins related to apoptosis in INS-1 cells with exposure to intermittent high glucose.

METHODSINS-1 cells cultured in vitro were divided into control group, persistent high glucose group (PHG), intermittent high glucose group (IHG), CoPP + intermittent high glucose group (CoPP+IHG), and ZnPP+ intermittent high glucose group (ZnPP+IHG). After 72 h of treatment with the corresponding protocols, the cells were examined for expressions of HO-1 protein by Western blotting and for expressions of Bax and Bcl-2 by immunocytochemistry.

RESULTSIn comparison with the control group, the cells in both PHG group and IHG group showed significantly increased expressions of HO-1 (P<0.01) and decreased Bcl-2/Bax ratios (P<0.05). The cells in CoPP+ IHG group exhibited a greater HO-1 protein expression but a lower Bcl-2/Bax ratio than those in IHG group (P<0.05) The ZnPP+IHG group demonstrated opposite changes in terms of HO-1, Bax and Bcl-2 expressions compared with the CoPP+IHG group.

CONCLUSIONIntermittent high glucose can lower Bcl-2/Bax ratio in INS-1 cells, and HO-1 may protect INS-1 cells against apoptosis possibly by up-regulating the Bcl-2/Bax ratio.

Animals ; Apoptosis ; drug effects ; Caspase 3 ; metabolism ; Cell Line ; Glucose ; administration & dosage ; adverse effects ; Heme Oxygenase (Decyclizing) ; metabolism ; Islets of Langerhans ; cytology ; drug effects ; Proto-Oncogene Proteins c-bcl-2 ; metabolism ; Rats ; bcl-2-Associated X Protein ; metabolism

OBJECTIVE: To investigate the effect of oral administration of insulin on insulitis beta cell apoptosis and diabetes in non-obese diabetic (NOD) mice, and to explore the mechanism of immune tolerance induced by insulin. METHODS: Eighty-six female NOD mice were randomly divided into an insulin group (n=43) and a phosphate buffered saline (PBS) group (n=43). From 4 weeks of age, the recombinant human insulin (Humulin R) 1 mg (70 microL) was administrated in the oral insulin group and 70 microL PBS in the control group respectively, twice per week before 12 weeks of age and then once weekly until 30 weeks. Insulitis and beta cell apoptosis of islets were observed at 12 weeks. IL-4 and IFN-gamma in the sera were measured by enzyme linked immunosorbent assay (ELISA). The expression levels of I-Abeta(g7), IL-4, IFN-gamma, IL-1beta, Fas and TGF-beta mRNA of islets, and IL-4, IFN-gamma, TGF-beta mRNA of Peyer's patch were measured by reverse transcription-polymerase chain reaction (RT-PCR) at 12 weeks. RESULTS: The incidences in the insulin group were significantly lower than those in the PBS group (55.6% vs 85.7% at 30 weeks, 70.4% vs 96.4% at 52 weeks, P<0.05). The insulitis scores in the insulin group were lower than those in the PBS group, but there was no statistical significance. Fas expression on islets and apoptotic beta cell rates in the insulin group were lower than those in the PBS group (P<0.05). In the insulin group, serum IL-4 levels were higher, and IFN-gamma levels were lower than those in the PBS group (P<0.05). The levels of I-Abeta(g7), IFN-gamma, IL-1beta and Fas mRNA transcription in islets and IFN-gamma mRNA transcription in Peyer's patch were both lower in the insulin group, and IL-4, TGF-beta mRNA levels were higher than those in the PBS group (P<0.05). CONCLUSION The specific autoantigen insulin may induce the immune tolerance and prevent the diabetes in NOD mice, but it cannot block the progression of insulitis. Oral administration of insulin can induce the regulatory T cells, and make Th1 to Th2 cytokine shifts in the system and islets, thus preventing the Fas-mediated beta-cell apoptosis and diabetes.
Administration, Oral ; Animals ; Apoptosis ; drug effects ; Cytokines ; metabolism ; Diabetes Mellitus, Type 1 ; drug therapy ; pathology ; Female ; Insulin, Regular, Human ; administration & dosage ; pharmacology ; Islets of Langerhans ; cytology ; drug effects ; Mice ; Mice, Inbred NOD ; Th1-Th2 Balance ; fas Receptor ; metabolism

OBJECTIVETo investigate the effect of potassium channel opener (diazoxide) on the islet cells apoptosis and bcl-2 and bax gene expressions in diabetic rats.

METHODSIslet cell apoptosis was induced by intraperitoneal injection of streptozocin (STZ). The rats were randomly allocated into normal control group (NC group), diabetes mellitus group (DM group), and diazoxide group (DIA group), all treated with diazoxide for 4 weeks. During and after the treatment, the general state, body weight, fasting plasma glucose (FPG), food intake, and oral glucose tolerance of the rats were assessed. The expressions of Bcl-2 and Bax in rat islet cells were measured by immunohistochemistry, and the cell apoptosis was analyzed by TUNEL assay.

RESULTSCompared with the NC group, the rats in the DM group showed significantly decreased body weight (P<0.05), increased blood glucose at o and 120 min after oral glucose administration, decreased expressions of Bcl-2 (P<0.01), increased expression of Bax (P<0.01), and increased islet cell apoptosis (P<0.05). Diazoxide treatment significantly decreased the body weight (P<0.05), decreased the blood glucose, increased Bcl-2 expression (P<0.01), decreased Bax expression (P<0.05), and reduced the islet cell apoptosis (P>0.05) of the diabetic rats.

CONCLUSIONBy causing potassium channel opening, diazoxide can obviously improve the oral glucose tolerance, reduce the body weight, and up-regulate Bcl-2 and down-regulate Bax expression in diabetic rats. Diazoxide can also reduce the apoptosis of the islet cells in diabetic rats.

Animals ; Apoptosis ; drug effects ; Diabetes Mellitus, Experimental ; metabolism ; Diazoxide ; pharmacology ; Islets of Langerhans ; cytology ; drug effects ; metabolism ; Male ; Proto-Oncogene Proteins c-bcl-2 ; metabolism ; Rats ; Rats, Sprague-Dawley ; bcl-2-Associated X Protein ; metabolism

OBJECTIVETo study the signaling pathways associated with lipopolysaccharide (LPS)-induced inflammation in islet micro-endothelial cells (IMECs) and the mechanism of pravastatin intervention.

METHODSIMECs exposed to LPS, SB203580, pravastatin, or SB203580+pravastatin were examined for cell apoptosis with Hoechst staining and flow cytometry and for expression levels of total-p38, photophosphorylation-p38 (p-p38) and iNOS with Western blotting.

RESULTSThe apoptosis rate and expression levels of total-p38, p-p38, iNOS in IMECs all increased after LPS exposure. Pravastatin, SB203580, and their combination significantly attenuated LPS-induced enhancement of cell apoptosis and total-p38, p-p38, and iNOS expressions in IMECs.

CONCLUSIONLPS-induced inflammatory toxicity in IMECs is associated with the activation of P38MAPK and iNOS/NO signaling pathways. Pravastatin can inhibit these pathways and suppress the apoptosis and necrosis of IMECs to relieve the cell inflammatory injuries.

Animals ; Apoptosis ; Endothelial Cells ; drug effects ; metabolism ; Endothelium, Vascular ; cytology ; Inflammation ; Islets of Langerhans ; blood supply ; MAP Kinase Signaling System ; drug effects ; Mice ; Nitric Oxide Synthase Type II ; metabolism ; Phosphorylation ; Pravastatin ; pharmacology ; p38 Mitogen-Activated Protein Kinases ; metabolism