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

To build the Dendrobium nobile -T2DM network, and elucidate the molecular mechanism of D. nobile to type 2 diabetes (T2DM). Collect the chemical composition of D. nobile and the targets on T2DM by retrieving database and documents, build the network of D. nobile to T2DM using the entity grammar systems inference rules. The molecular mechanism of D. nobile to T2DM includes: (1) regulating lipid metabolism by lowering triglyceride; (2) reducing insulin resistance; (3) protecting islet cells; (4) promoting the glucose-dependent insulin tropic peptide (GIP) secretion; (5) inhibiting calcium channel. Under the guidance of network pharmacology, through entity grammar systems inference rules we elucidate the molecular mechanism of D. nobile to T2DM, and provide the basis for the further development of health care products based on D. nobile.
Animals ; Calcium Channels ; genetics ; metabolism ; Databases, Factual ; Dendrobium ; chemistry ; Diabetes Mellitus, Type 2 ; drug therapy ; genetics ; metabolism ; Drugs, Chinese Herbal ; administration & dosage ; chemistry ; Gene Regulatory Networks ; drug effects ; Humans ; Hypoglycemic Agents ; administration & dosage ; chemistry ; Insulin Resistance ; Islets of Langerhans ; metabolism ; Triglycerides ; metabolism

The polysaccharides from pumpkin fruit (PP) were obtained and purified by hot-water extraction, anion-exchange chromatography, and gel column chromatography. The physicochemical properties of PP were determined by gel filtration chromatography, gas chromatography, fourier transform infrared (FTIR) spectroscopy, and nuclear magnetic resonance (NMR) spectroscopy. Results indicated that the molecular weight of PP was about 23 kDa and PP was composed of D-Arabinose, D-Mannose, D-Glucose, and D-Galactose with a molar ratio of 1 : 7.79 : 70.32 : 7.05. FTIR and NMR spectra indicated that PP was the polysaccharide containing pyranose ring. Additionally, PP protected islets cells from streptozotocin (STZ) injury in vitro via increasing the levels of super-oxide dismutase (SOD) and malondialdehyde (MDA) and reducing the production of NO. The experiment of reverse transcriptase-polymerase chain reaction further proved that PP inhibited apoptosis via modulating the expression of Bax/Bcl-2 in STZ-damaged islet cells. In conclusion, PP could be explored as a novel agent for the treatment of diabetes mellitus.
Animals ; Apoptosis ; drug effects ; Chromatography, Gas ; Chromatography, Gel ; Cucurbita ; chemistry ; Diabetes Mellitus, Experimental ; drug therapy ; Islets of Langerhans ; drug effects ; injuries ; Magnetic Resonance Spectroscopy ; Malondialdehyde ; analysis ; Molecular Weight ; Monosaccharides ; analysis ; Nitric Oxide ; biosynthesis ; Polysaccharides ; chemistry ; pharmacology ; Rats ; Rats, Sprague-Dawley ; Reverse Transcriptase Polymerase Chain Reaction ; Spectroscopy, Fourier Transform Infrared ; Superoxide Dismutase ; drug effects ; bcl-2-Associated X Protein ; drug effects

The Goto-Kakizaki (GK) rat is a spontaneous type 2 diabetic animal model, which is characterized by a progressive loss of beta islet cells with fibrosis. In the present study, the hypoglycemic effect of asiatic acid (AA) in GK rats was examined. GK rats receiving AA at a daily dose of 25 mg·kg(-1) for four weeks showed a significant reduction in blood glucose levels. Age-matched normal Wistar rats were given 0.5% sodium carboxymethyl cellulose (CMC-Na) solution for the same periods and used as control. Compared to the normal Wistar rats, GK rats treated with AA showed improvement in insulin resistance partially through decreasing glucose level (P < 0.01) and insulin level (P < 0.05). Furthermore, the results of immunohistochemistry indicate that AA treatment reduced islet fibrosis in GK rats. Fibronectin, a key protein related to islet fibrosis, was over-expressed in GK rats, which was reversed significantly by AA treatment (P < 0.05). These findings suggest that AA has a beneficial effect on lowering blood glucose levels in GK rats and improves fibrosis of islets in diabetes, which may play a role in the prevention of islets dysfunction.
Animals ; Blood Glucose ; metabolism ; Centella ; chemistry ; Diabetes Mellitus, Type 2 ; drug therapy ; pathology ; Disease Models, Animal ; Fibronectins ; metabolism ; Fibrosis ; Glucose Tolerance Test ; Hyperglycemia ; drug therapy ; pathology ; Insulin ; blood ; Insulin Resistance ; Islets of Langerhans ; drug effects ; pathology ; Male ; Pancreatic Diseases ; metabolism ; pathology ; prevention & control ; Pentacyclic Triterpenes ; pharmacology ; therapeutic use ; Phytotherapy ; Plant Extracts ; pharmacology ; therapeutic use ; Rats, Inbred Strains

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

The protective effects of Da Chai Hu Granules (DCHKL) on islet cells which were incubated with 4 mmol x L(-1) alloxan (AXN) were studied. The viability of islet cells were measured with MTT. Insulin released into medium and in islets was detected by radioimmunoassay. Cell apoptosis rate was determined by flow cytometry. The expression of anti-apoptotic gene Bcl-2 and pro-apoptotic gene Bax in islet cells were measured with RT-PCR (reverse transcription polymerase chain reaction). Serum containing DCHKL can promote the activity of islet cells significantly (P < 0.01). Basal insulin secretion and high glucose-stimulated insulin secretion increased significantly (P < 0.01). Serum containing DCHKL can inhibit apoptosis of islet cells, the ratio of apoptosis was decreased. Serum containing DCHKL increased expression of Bcl-2 mRNA and decreased expression of Bax mRNA. DCHKL can significantly promote proliferation of islet cells and increase the amount of basal secretion of pancreatic islet cells and high glucose-stimulated insulin secretion. The expression of Bcl-2 increased significantly. The expression of Bax decreased significantly. DCHKL have a protective effect on the islet cells.
Alloxan ; toxicity ; Animals ; Apoptosis ; drug effects ; Cell Proliferation ; drug effects ; Cells, Cultured ; Drug Combinations ; Drugs, Chinese Herbal ; isolation & purification ; pharmacology ; Insulin ; metabolism ; secretion ; Islets of Langerhans ; cytology ; drug effects ; metabolism ; Plants, Medicinal ; chemistry ; Protective Agents ; pharmacology ; Proto-Oncogene Proteins c-bcl-2 ; genetics ; metabolism ; RNA, Messenger ; metabolism ; Rats ; Rats, Sprague-Dawley ; bcl-2-Associated X Protein ; genetics ; 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

BACKGROUNDSuppressor of cytokine signaling (SOCS) proteins are inhibitors of cytokine signaling pathway involved in negative feedback loops. Although SOCS1 is an important intracellular suppressor of apoptosis in a variety of cell types, its role in cytokine-induced pancreatic β-cell apoptosis remains unclear. The present study investigated potential effects of SOCS1 on the cytokine-induced pancreatic β-cell apoptosis.

METHODSAfter successfully transfected with SOCS1/pEGFP-C1 or pEGFP-C1 plasmids to overexpress SOCS1, RINm5F (rat insulinoma cell line) cells were exposed to cytokines, interferon (IFN)-γ alone, IFN-γ+interleukin (IL)-1β, IFN-β+IL-1β+tumor necrosis factor (TNF)-α respectively. Pancreatic β-cell apoptosis was assessed by using MTT, FACS, and caspase-3 activity assays. Protein phosphorylation of Janus kinase 2 (JAK2) and signal transducers and activators of transcription 1 (STAT1) were verified by Western blotting and mRNA expression of inducible nitric oxide synthase (iNOS), NF-κB and Fas were analyzed by RT-PCR.

RESULTSOverexpression of SOCS1 in RINm5F cells was shown to attenuate IFN-γ alone, IFN-γ+IL-1β and IFN-γ+TNF-α+IL-1β mediated apoptosis. Phosphorylation of JAK2 and STAT1 significantly decreased in RINm5F cells which overexpressed SOCS1 protein. Overexpression of SOCS1 significantly suppressed cytokine-induced iNOS mRNA levels.

CONCLUSIONOverexpression of SOCS1 protects pancreatic islets from cytokine-induced cell apoptosis via the JAK2/STAT1 pathway.

Animals ; Apoptosis ; drug effects ; genetics ; Blotting, Western ; Cell Line ; Cytokines ; pharmacology ; Interferon-gamma ; pharmacology ; Interleukin-1 ; pharmacology ; Islets of Langerhans ; cytology ; drug effects ; Janus Kinase 2 ; metabolism ; Phosphorylation ; drug effects ; Rats ; Reverse Transcriptase Polymerase Chain Reaction ; STAT1 Transcription Factor ; genetics ; metabolism ; Signal Transduction ; drug effects ; Suppressor of Cytokine Signaling 1 Protein ; Suppressor of Cytokine Signaling Proteins ; genetics ; metabolism ; Tumor Necrosis Factor-alpha ; pharmacology

OBJECTIVETo establish the method for cotransferring human A20 gene and human heme oxygenase-1 (HO-1) gene into the isolated rat islets using lentiviral transfection system, and to study the protective effect of A20 and HO-1 protein against the apoptosis induced by cycloheximide (CHX) and TNF-α, and finally to explore the underlying mechanism.

METHODThe A20 gene and HO-1 gene were cloned and inserted into the lentiviral transfection system. The efficacy of gene transfer was measured by the intensity of the enhanced green fluorescent protein (EGFP) fluorescence-positive islets. Western blot was applied to verify the expression of the A20 and HO-1 genes. To induce apoptosis in vitro, the isolated islets were treated with CHX+TNF-α, terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) and the fluorescence-activated cell sorting (FACS) methods were used to evaluate the apoptosis of the islet cells and Western blot was used to detect caspase-3 activation.

RESULT(1) A20 and HO-1 genes were introduced into the isolated islets by lentiviral transfection, both of the genes were highly expressed in the islets after 96 hours culture detected by Western blot method. (2) The insulin levels in the cell culture medium from A20 and/or HO-1 transgenic islets were significantly higher than that in non-transgenic controls (P < 0.01). (3)After CHX + TNF-alpha treatment, the cell culture medium insulin concentration in the A20 gene transfected group [(93.58 ± 4.12)µg/ml], HO-1 gene transfected group [(88.98 ± 4.77) µg/ml ] and A20/HO-1 co-transfected group [(103.33 ± 3.16) µg/ml] were significantly higher than that in the EGFP group [(9.03 ± 0.65) µg/ml ] and the control group [(8.86 ± 0.38) µg/ml] (P < 0.001). Minimum expression level of the activated caspase-3 was found in the A20/HO-1 co-transfected group.

CONCLUSIONThe lentiviral gene transfer system was an efficient and stable gene transfer vector, the over-expressed A20 and HO-1 protein delivered via lentivirus could preserve rats' islets function and act against the apoptosis induced by CHX and TNF-α.

Animals ; Apoptosis ; drug effects ; Caspase 3 ; metabolism ; Cell Line ; DNA-Binding Proteins ; genetics ; metabolism ; Female ; Flow Cytometry ; Genetic Vectors ; Heme Oxygenase-1 ; genetics ; metabolism ; Humans ; Insulin ; metabolism ; Intracellular Signaling Peptides and Proteins ; genetics ; metabolism ; Islets of Langerhans ; drug effects ; enzymology ; physiology ; Lentivirus ; genetics ; Male ; Nuclear Proteins ; genetics ; metabolism ; Rats ; Rats, Sprague-Dawley ; Transfection ; methods ; Tumor Necrosis Factor alpha-Induced Protein 3 ; Tumor Necrosis Factor-alpha ; pharmacology

AIM: To synthesize three novel esterified-derivatives of mangiferin and evaluate their hypoglycemic activities. METHODS: Acetic, propionic, and butyric anhydride were reacted with mangiferin, respectively. The hypoglycemic activity of the derivatives was evaluated using a hyperglycemic mouse model induced by streptozotocin (STZ), and the islet cells were checked by biopsy inspection. RESULTS: 7, 2', 3', 4', 6'-penta-acetyl-mangiferin (PAM), 3, 6, 7, 2', 3', 4', 6'-hepta-propionyl-mangiferin (HPM) and 3, 6, 7, 2', 3', 4'-hexa-butyryl-mangiferin (HBM) were synthesized and their structures were identified by MS,(1)H, (13)C NMR, and 2D NMR. These three compounds were reported for the first time. PAM group (0.5, 0.25 mmol·kg(-1)), HPM group (0.5, 0.25 mmol·kg(-1)), and HBM group (0.5, 0.25, 0.125 mmol·kg(-1)) mice showed strong hypoglycemic activity (P < 0.01); mangiferin group (1, 0.5 mmol·kg(-1)), PAM group (0.125 mmol·kg(-1)) and HPM group (0.125 mmol·kg(-1)) showed marginal hypoglycemic activity (P < 0.05); mangiferin group (0.25 mmol·kg(-1)) had the potential for a hypoglycemic effect, although it did not demonstrate that statistically. In histological examination, the islet cells of the PAM, HPM, and HBM groups could recover from the STZ damage; islet cells of the mangiferin group could recover also, but less than the esterified-derivative groups. CONCLUSION Derivatives could repair the damaged islet cells, and had higher lipid-solubility and stronger hypoglycemic activity than mangiferin itself. There existed a structure activity effect, and a solubility effect relationship: the larger esterification moieties, or the higher lipid-solubility, the stronger the hypoglycemic activity (no ester → acetyl → propionyl → butyryl). Esterified derivatives of mangiferin are potential compounds for new anti-diabetes drugs.
Animals ; Diabetes Mellitus, Experimental ; drug therapy ; Esterification ; Humans ; Hypoglycemic Agents ; administration & dosage ; chemical synthesis ; chemistry ; Islets of Langerhans ; drug effects ; Male ; Mice ; Molecular Structure ; Xanthones ; administration & dosage ; chemical synthesis ; chemistry