Insulin Staining Research Articles

Characterizing Insulin Sensitivity in Adult LEW.1WR1 Rats

Diabetes prevention is a large topic of research that is focused on nutritional and exercise‐based interventions with some genetic predisposition based interventions. FAT10 is a ubiquitin‐like protein and Type 1 Diabetes (T1D) susceptibility gene that may play a role in age‐related inflammation, adiposity, cancer, and kidney disease. The young T1D susceptible, LEW.1WR1 rat overexpresses FAT10 and has higher fasting concentrations of blood insulin. It is unclear how the overexpression of FAT10 effects directly affects insulin sensitivity, secretion, or production. It is also unclear if the initial insulin sensitivity of this animal model plays a role in disease susceptibility. Therefore we hypothesized that older LEW.1WR1 rats will have markers of increased insulin resistance like increased insulin and beta cell mass due to the poor regulation of FAT10 expression in this model. The objective of this study was to characterize insulin sensitivity, insulin levels, and characterize the relative beta cell size of adult LEW.1WR1 rats with or without dietary stress to understand if FAT10 expression plays a role in the regulation of inflammation and aging‐induced insulin resistance. To test this hypothesis we used LEW.1WR1 and LEW.SsNHsd rat and monitored weight gain and glucose tolerance over the course of 12 weeks on a high fat or control diet; we also isolated pancreata and used immunohistochemistry staining for insulin to analyze islet size and insulin staining. The LEW.ssNHsd rat served as a control rat because it does not have the alteration in the FAT10 promoter region. Glucose tolerance tests were performed prior to starting the diet as a baseline, and after 10 weeks on the diet to determine the effects of diet and aging on the rat groups in regards to Insulin Sensitivity. We observed that in the course of 10 weeks the control LEW.1WR1 rats became significantly more glucose intolerant and had increased insulin levels. The control LEW.1WR1 rats also gained weight at a rate similar to the high‐fat diet, a diet that is traditionally used to induce insulin resistance and glucose intolerance. This data suggests that FAT10 may be playing a role in age‐related adiposity, glucose intolerance, insulin sensitivity, and beta‐cell changes in the LEW.1WR1 rat. This study begins to lay the groundwork for understanding how alterations in FAT10 and metabolism increase T1D susceptibility.Support or Funding InformationThe University of Alabama in HuntsvilleLouis Stokes Alliance for Minority Participation (NSF)This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Characterizing the Insulin Staining of LEW.1WR1 and LEW/SsNHsd Rats in Response to Polyinosinic‐Cytidylic Acid

The experimental model LEW.1WR1(1WR1) rats show increased type 1 diabetes (T1D) onset with the administration polyinosinic‐polycytidylic acid (PIC). The susceptibility window of inducible T1D in the LEW rat occurs between 21–35 days (3–5 weeks) of life, which is a similar life stage of the onset of human T1D (peak age of onset is 14 years old). The susceptibility of this model is related to FAT10 overexpression, a ubiquitin‐like protein that plays an unclear role in the regulation of lipid metabolism. The objective of this study was to compare the size and number of insulin stained pancreatic islets in 1WR1 rats treated with PIC with control rats during disease induction. Using immunohistochemistry we were able to visualize pancreatic islet infiltration by CD3+ and CD68+ stained cells. We observed increased immune cells in the PIC treated pancreata. There were also no significant differences in blood insulin level which appeared to be trending up. Using blinded trained scorers we observed islet size varied as well as intensity of staining. We believe that the beta cells may be responding to the inflammatory stimulus which could play a role in increasing the susceptibility to T1D.Support or Funding InformationThe University of Alabama in HuntsvilleThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

A Simple and Effective Non-Human Primate Diabetic Model Combining Sub-Total Pancreatectomy and Low-Dose Streptozotocin Injection

BACKGROUND. Current non-human primate diabetic models, namely those induced by total pancreatectomy or streptozotocin (STZ) injection, suffer from several disadvantages, including a long surgical procedure, the need for continual digestive enzyme replacement, and a delayed oral intake after total pancreatectomy and severe hypoglycemia and hepatic/renal toxicity with high-dose STZ injection. AIM. To construct and optimize a non-human primate diabetic model that avoids the disadvantages of current approaches and compare it to the STZ model. METHODS. Diabetes was induced in male Cynomolgus monkeys (n=4) by performing subtotal pancreatectomy followed by low-dose STZ injection (30 [n=1], 45 [n=2] and 60 [n=1] mg/kg). This model was compared to STZ injection only (60 [n=1] and 100 [n=9] mg/kg) regarding the development of diabetes (serum C-peptide and pancreatic anti-insulin staining), the liver (glutamine-ornithine-transaminase and glutamine-pyruvate-trasnaminase levels) and kidney functions (BUN and creatinine levels), and the general condition (weight loss, food intake, and activity). RESULTS. The serum C-peptide levels after glucose challenge in the combined model were comparable (0 ng/mL) to those with high-dose STZ injection (100 mg/kg). The absence of pancreatic insulin staining was demonstrated when 60 mg/kg STZ was used after subtotal pancreatectomy and with 100 mg/kg STZ injection only. The combined model did not suffer from hypoglycemic episodes and showed better activity and oral intake than the STZ-only model. Liver enzyme levels were markedly lower in the new model, while BUN and creatinine levels were higher than with STZ alone. CONCLUSIONS. Diabetes was successfully induced using the combined technique without the need for a lengthy operation or continual digestive enzyme replacement. In addition, the reduction in the pancreatic volume allowed for lower STZ utilization which led to less hepatic toxicity and the absence of hypoglycemic episodes. However, adequate fluid administration may be required to guard against renal STZ toxicity.

Dendrobium huoshanense polysaccharide regulates hepatic glucose homeostasis and pancreatic β-cell function in type 2 diabetic mice

In the present study, the hypoglycemic mechanism of a homogeneous Dendrobium huoshanense polysaccharide (GXG) was investigated using type 2 diabetic (T2D) mouse model. With a 5-week oral administration of GXG, the levels of fasting blood glucose, glycosylated serum protein and serum insulin in T2D mice were decreased, and the glucose tolerance and the insulin sensitivity were improved. The histological analysis, the periodic acid-schiff staining and the immunofluorescence staining of insulin, glucagon and apoptosis showed that the hypoglycemic effect of GXG was related to the improvement of pancreatic β-cell quantity and function and the regulation of hepatic glucose metabolism. Western blot analysis indicated that the up-regulated IRS1-PI3K-Akt phosphorylation followed by the down-regulated FoxO1/GSK 3β phosphorylation contributed to the enhanced glycogen synthesis and the decreased gluconeogenesis by GXG, suggesting that the response of insulin-mediated IRS1-PI3K-Akt-FoxO1/GSK 3β signaling to GXG might be the required mechanism for GXG-ameliorated development of type 2 diabetes.

Endoplasmic Reticulum Chaperone Glucose-Regulated Protein 94 Is Essential for Proinsulin Handling

Although endoplasmic reticulum (ER) chaperone binding to mutant proinsulin has been reported, the role of protein chaperones in the handling of wild-type proinsulin is underinvestigated. Here, we have explored the importance of glucose-regulated protein 94 (GRP94), a prominent ER chaperone known to fold insulin-like growth factors, in proinsulin handling within β-cells. We found that GRP94 coimmunoprecipitated with proinsulin and that inhibition of GRP94 function and/or expression reduced glucose-dependent insulin secretion, shortened proinsulin half-life, and lowered intracellular proinsulin and insulin levels. This phenotype was accompanied by post-ER proinsulin misprocessing and higher numbers of enlarged insulin granules that contained amorphic material with reduced immunogold staining for mature insulin. Insulin granule exocytosis was accelerated twofold, but the secreted insulin had diminished bioactivity. Moreover, GRP94 knockdown or knockout in β-cells selectively activated protein kinase R–like endoplasmic reticulum kinase (PERK), without increasing apoptosis levels. Finally, GRP94 mRNA was overexpressed in islets from patients with type 2 diabetes. We conclude that GRP94 is a chaperone crucial for proinsulin handling and insulin secretion.

Histological and Histochemical Methods for Staining of Insulin: A Comparative Analysis

Histological and Histochemical Methods for Staining of Insulin: A Comparative Analysis

Hypothermic pulsatile perfusion of human pancreas: Preliminary technical feasibility study based on histology

BackgroundThere are currently two approaches to hypothermic preservation for most solid organs: static or dynamic. Cold storage is the main method used for static storage (SS), while hypothermic pulsatile perfusion (HPP) and other machine perfusion-based methods, such as normothermic machine perfusion and oxygen persufflation, are the methods used for dynamic preservation. HPP is currently approved for kidney transplantation. MethodsWe evaluated, for the first time, the feasibility of HPP on 11 human pancreases contraindicated for clinical transplantation because of advanced age and/or history of severe alcoholism and/or abnormal laboratory tests. Two pancreases were used as SS controls, pancreas splitting was performed on 2 other pancreases for SS and HPP and 7 pancreases were tested for HPP. HPP preservation lasted 24 h at 25 mmHg. Resistance index was continuously monitored and pancreas and duodenum histology was evaluated every 6 h. ResultsThe main finding was the complete absence of edema of the pancreas and duodenum at all time-points during HPP. Insulin, glucagon and somatostatin staining was normal. Resistance index decreased during the first 12 h and remained stable thereafter. Conclusion24 h hypothermic pulsatile perfusion of marginal human pancreas-duodenum organs was feasible with no deleterious parenchymal effect. These observations encourage us to further develop this technique and evaluate the safety of HPP after clinical transplantation.

The Suppressive Function of the Human Regulatory Macrophages In-Vitro have more Potency but not In-Vivo

Centre for Transplant & Renal Research. Introduction Human regulatory macrophages (Mregs) have been shown to suppress mitogen-driven T cell proliferation in vitro and are under evaluation as a cellular therapy in renal transplantation in THE ONE STUDY clinical trial. In this study, we investigated whether human Mregs were capable of suppressing the allogeneic response in vitro and protecting islet xeno-grafts in humanizing mice in vivo. Methods Human CD14+ cells were isolated from healthy donor peripheral blood monocytes (PBMCs) using CD14 magnetic beads. Mregs induction was performed by culturing CD14+ cells with M-CSF for 6 days and be stimulated with IFN-γ for a further 24 hr. The phenotype of Mregs was characterized by flow cytometry, and their suppressive activity was tested by mixed-lymphocyte reaction (MLR) using human PBMCs as responder cells, autologous Mregs as suppressor cells and irradiated allogeneic PBMCs as stimulator cells. In a separate transwell MLR setting, responder and allogeneic stimulator cells were cultured in the upper chamber and autologous Mregs were seeded in the lower chamber. Supernatants collected from MLR cultures were used for cytokine detection. Isolated the neonatal porcine islet cell clusters (NICCs) and cultured for 6 days. In vivo, every 5,000 IEQ NICCs were transplanted into NOD-SCID IL2R gamma -/- mice under the two sides of renal capsules. Adoptive transfer of human PBMCs and Mregs were suspended in PBS and injected into mice at doses of 10×106 and 2×106 by tail vein within 7 days after transplant. Graft rejection was defined as little or no intact graft with a heavy lymphocytic infiltrate on histological examination, survival was analyzed by H&E staining and endocrine secreting cells was analyzed by insulin staining. Results The resulting induced human Mregs demonstrated a typical Mregs phenotype, CD14lowCD80lowCD86+HLA-DR+CD83-/lowCD16-, and as a result, potent suppression of proliferating alloreactive PBMC even at Mregs: responder cells ratios >1:16. Separation of Mregs from responder and allogeneic stimulators in a transwell MLR system had the mild impact on their suppressive potency in the allogeneic response at all ratios of Mregs: responder cells tested. Upregulated levels of Mregs function related molecules TGF-b and IDO were detected in the supernatants collected from both non-transwell and transwell MLR cultures containing Mregs. In treated mice, the human PBMC were identified in the porcine-NICC-xenografts, as well as systemically in the spleens, blood, and kidneys. However, injected Mregs cannot be detected by flow cytometry, and there were no intact xenografts were found with mid-term. Conclusions In vitro induced human Mregs showed the capacity to suppress the allogeneic response in vitro and that was not cell-cell contact dependent. The porcine-NICC-xenografts cannot be protected by Human-Mregs in vivo as Mregs cannot proliferation. The suppressive function of the Mregs have more potency in vitro, but not in vivo.

The revascular and transplanted effects of vascular endothelial cells on islets grafts

Objective To investigate the revascular and transplanted effects of islet grafts after co-transplantation with vascular endothelial cells (ECs) in diabetic rats. Methods The rat ECs and islet cells were isolated and purified, then subcutaneously co-transplanted to the inbred SD male rats with diabetes mellitus, the group of islets transplanted alone, group of phosphate buffered solution, and group of normal rats served as control. Islet grafts revascularization degree, islet cells activity and apoptosis were observed by immunohistochemical double staining of CD31, insulin and factor associated suicide (Fas) antibody. The results of intraperitoneal glucose tolerance test (IPGTT) and intraperitoneal insulin tolerance test (IPITT), the blood glucose and insulin levels of the rats and the survival time of the islet grafts were compared. Results The blood glucose concentrations of IPGTT and IPITT, the blood glucose and insulin levels of rats analyzed by multivariate analysis in the ECs and islets transplantation group were better than those in the islets transplantation alone group (P<0.05). The islet grafts mean survival time of the ECs and islets transplantation group was longer than that of the islets transplantation alone group (P<0.05). On the 7th day after transplantation, mean microvascular density of islet grafts per square millimeter in the ECs and islets transplantation group was 26.4±6.1, significantly greater than that in the islets transplantation alone group 18.3±5.7 (P<0.05). In the ECs and islets transplantation group, insulin staining intensity was higher than that in the islets transplantation alone group (P<0.05), while factor associated suicide(Fas) staining intensity was lower than that in the islets transplantation alone group (P<0.05). Conclusion Co-transplantation with ECs could promote the revascularization of islet grafts and improve the effect of islet transplantation. (Chin J Endocrinol Metab, 2018, 34: 516-521) Key words: Islet transplantation; Endothelial cells; Revascularization; Diabetes mellitus

Initial Clinical Evaluation of VC-01TM Combination Product—A Stem Cell–Derived Islet Replacement for Type 1 Diabetes (T1D)

VC-01 is a novel cell replacement therapy being developed as a potential long-term diabetes therapy to more effectively control glycemia, reduce hypoglycemia risk and mitigate diabetes-related complications. VC-01 is derived from directed differentiation of human embryonic stem cells to pancreatic progenitor cells, which are loaded into a durable, retrievable delivery device and then implanted subcutaneously. Once implanted and matured, the cells secrete insulin and other islet hormones in response to blood glucose levels. The delivery device is immunoprotective to implanted cells. VC-01 is currently being evaluated in a 24-month open-label, dose-escalating Phase 1/2 study in T1D patients with minimal insulin-producing β-cell function. Cohort 1 has evaluated product at a subtherapeutic dose to assess initial safety and tolerability and establish implantation techniques. To date, 19 subjects have been implanted and evaluated throughout implantation duration until final product explant. Product has been safe and well tolerated; adverse events have been relatively minor and generally related to the surgical procedure. The delivery device has provided protection against the host adaptive immune system with no evidence of allogeneic or autoimmune rejection or sensitization based upon a sensitive panel of immune function tests. No off-target growth of donor cells has been detected. The potential for prolonged cell survival has been demonstrated, as long as 24 months, but has been inconsistent among subjects and primarily limited by a foreign body response to the device component. Positive immunohistochemical staining for pancreatic islet cell markers NKX6-1, insulin, and glucagon has been observed. These preliminary results demonstrate the immune-protective nature of the encapsulation device and safety of this human stem cell-derived product, but also indicate the ongoing requirement for optimization of the host response to device materials. Disclosure R.R. Henry: Consultant; Self; Abbott, Alere Inc., AstraZeneca. Research Support; Self; AstaReal. Advisory Panel; Self; Boehringer Ingelheim Pharmaceuticals, Inc.. Consultant; Self; Bristol-Myers Squibb Company. Advisory Panel; Self; Elcelyx Therapeutics, Inc.. Research Support; Self; Eli Lilly and Company, Hitachi, Ltd.. Advisory Panel; Self; AstraZeneca. Consultant; Self; Boehringer Ingelheim Pharmaceuticals, Inc.. Advisory Panel; Self; Intarcia Therapeutics, Inc.. Consultant; Self; Intarcia Therapeutics, Inc., Ionis Pharmaceuticals, Inc., Janssen Pharmaceuticals, Inc.. Advisory Panel; Self; Johnson &amp; Johnson Services, Inc.. Research Support; Self; Lexicon Pharmaceuticals, Inc.. Consultant; Self; Ligand Pharmaceuticals, Inc.. Advisory Panel; Self; Merck &amp; Co., Inc.. Consultant; Self; Merck &amp; Co., Inc.. Research Support; Self; Viacyte, Inc.. Consultant; Self; Sanofi-Aventis. Advisory Panel; Self; Sanofi-Aventis. J. Pettus: Advisory Panel; Self; Sanofi, Novo Nordisk Inc.. Consultant; Self; MannKind Corporation. Advisory Panel; Self; Insulet Corporation. Consultant; Self; Senseonics. J. Wilensky: None. A. Shapiro: Consultant; Self; Viacyte, Inc., Protokinetix. P.A. Senior: Consultant; Self; Abbott, AstraZeneca. Research Support; Self; AstraZeneca, Prometic Life Sciences Inc., Novo Nordisk Inc., Sanofi. Consultant; Self; Eli Lilly and Company. Speaker's Bureau; Self; Eli Lilly and Company, Novo Nordisk Inc.. Consultant; Self; Novo Nordisk Inc., Janssen Pharmaceuticals, Inc.. Speaker's Bureau; Self; Janssen Pharmaceuticals, Inc.. Consultant; Self; Boehringer Ingelheim Pharmaceuticals, Inc.. Speaker's Bureau; Self; AstraZeneca, Merck &amp; Co., Inc., Abbott. Research Support; Self; Viacyte, Inc. B. Roep: Consultant; Self; Viacyte, Inc.. Research Support; Self; Viacyte, Inc. R. Wang: Employee; Self; Viacyte, Inc.. Stock/Shareholder; Self; Sanofi. E.J. Kroon: Employee; Self; Viacyte, Inc. M. Scott: Stock/Shareholder; Self; Viacyte, Inc.. K. D'Amour: None. H.L. Foyt: Employee; Self; Viacyte, Inc.. Stock/Shareholder; Self; Viacyte, Inc..

Subcutaneous Transplantation of MIN6 Beta Cells Embedded in mPEG-Ala Hydrogel

The liver is the current site of choice for clinical islet transplantation, but many intraportal grafts were lost in the early stage of transplantation. Other disadvantages include the difficulty of monitoring the islets and procedure-associated complications. In contrast, the subcutaneous space offers the advantages of a large space, a less invasive procedure and easy graft monitoring and removal. However, islet transplantation into an unmodified subcutaneous site has poor efficacy; possibly due to poor oxygenation and inadequate vascularization of the transplanted tissue. In this study, we tested the feasibility of subcutaneous transplantation of MIN6 beta cells embedded in temperature-sensitive poly(ethylene glycol) methyl ether (mPEG)-Ala hydrogels as scaffolds. After culturing for 14 days, the viability of MIN6 beta cells in mPEG-Ala hydrogel was comparable with those in medium, either assayed by MTT or LIVE/DEAD. Static incubation showed that both had comparable insulin secretion. For in vivo experiments, we infected MIN6 beta cells with luciferase by AAV and then transplanted 5*106 cells embedded in mPEG-Ala hydrogel into the subcutaneous space of each nude mouse’s upper back. Positive In Vivo Imaging System (IVIS) images and positive insulin staining of tissue histology were observed up to 41 days after transplantation. Meanwhile, we incubated MIN6 beta cells with chitosan-coated superparamagnetic iron oxide (CSPIO) overnight and then transplanted 5*106 MIN6 beta cells into the subcutaneous tissue of each nude mouse’s left flank. The graft of CSPIO-labeled MIN6 beta cells was visualized on Magnetic Resonance (MR) scans as distinct hypointense spots on T2-weighted images located at the transplantation site at day 6 and 20. These results indicate that subcutaneous transplantation of MIN6 beta cells embedded in temperature-sensitive mPEG-Ala hydrogels is feasible. Moreover, the IVIS and MR imaging are useful tools for detecting and monitoring beta cells at the subcutaneous site. Disclosure J. Juang: None.H. Lin: None.C. Chen: None.C. Kao: None.S. Wu: None.S. Lin: None.C. Shen: None.J. Wang: None.I. Chu: None.

Regeneration of islet β-cells in tree shrews and rats.

BackgroudCurrent understanding of injury and regeneration of islet β‐cells in diabetes is mainly based on rodent studies. The tree shrew is now generally accepted as being among the closest living relatives of primates, and has been widely used in animal experimentation. However, there are few reports on islet cell composition and regeneration of β‐cells in tree shrews.MethodsIn this study, we examined the changes in islet cell composition and regeneration of β‐cells after streptozotocin (STZ) treatment in tree shrews compared with Sprague‐Dawley rats. Injury and regeneration of islet β‐cells were observed using hematoxylin and eosin (HE) staining and immunohistochemical staining for insulin, glucagon, somatostatin and PDX‐1.ResultsOur data showed that in rats islet injury was most obvious on day 3 after injection, and islet morphologies were significantly restored by day 21. Regeneration of islet β‐cells was very pronounced in rats, and mainly involved regeneration of centro‐acinar cells and transformation of extra‐islet ductal cells. In tree shrews, the regeneration of islet β‐cells was not as significant. On days 3 and 7, only scattered regenerated cells were observed in the remaining islets. Further, no regeneration of centro‐acinar cells was observed.ConclusionThe results suggest that the repair mechanism of islet β‐cells in tree shrews is similar to that of humans.

Protective Effect of Ipragliflozin on Pancreatic Islet Cells in Obese Type 2 Diabetic db/db Mice.

Ipragliflozin is a selective sodium glucose cotransporter 2 (SGLT2) inhibitor that increases urinary glucose excretion and subsequently improves hyperglycemia in patients with type 2 diabetes mellitus (T2DM). To assess the beneficial effect of ipragliflozin on the mass and function of pancreatic β-cells under diabetic conditions, obese T2DM db/db mice were treated with ipragliflozin for 5 weeks. Glucose and lipid metabolism parameters, pathological changes in pancreatic islet cells and insulin content were evaluated. Pathological examination of pancreatic islet cells comprised measuring the ratios of insulin- and glucagon-positive cells and levels of oxidative stress markers. Hemoglobin A1c, plasma glucose, non-esterified fatty acid and triglyceride levels in ipragliflozin-treated groups were reduced compared to the diabetic control (DM-control) group. Histopathological examination of pancreatic islet cells revealed strong insulin staining and reduced glucagon staining in the ipragliflozin 10 mg/kg-treated group compared with the DM-control group. The ratio of α- to β-cell mass was lower in the ipragliflozin 10 mg/kg-treated group than the DM-control group and was similar to that of the non-diabetic control group. The density of immunostaining for 4-hydroxy-2-nonenal, an oxidative stress marker, in pancreatic islets was significantly lower in the ipragliflozin 10 mg/kg-treated group than the DM-control group. Pancreatic insulin content tended to be higher in the ipragliflozin-treated groups than the DM-control group. Our findings demonstrate the benefit of ipragliflozin treatment in improving glucolipotoxicity and reducing oxidative stress in pancreatic islet cells. Treatment with ipragliflozin may protect against the progressive loss of islet β-cells in patients with T2DM.

Alloxan-induced diabetes exacerbates coronary atherosclerosis and calcification in Ossabaw miniature swine with metabolic syndrome

BackgroundThere is a preponderance of evidence implicating diabetes with increased coronary artery disease (CAD) and calcification (CAC) in human patients with metabolic syndrome (MetS), but the effect of diabetes on CAD severity in animal models remains controversial. We investigated whether diabetes exacerbates CAD/CAC and intracellular free calcium ([Ca2+]i) dysregulation in the clinically relevant Ossabaw miniature swine model of MetS.MethodsSixteen swine, eight with alloxan-induced diabetes, were fed a hypercaloric, atherogenic diet for 6 months. Alloxan-induced pancreatic beta cell damage was examined by immunohistochemical staining of insulin. The metabolic profile was confirmed by body weight, complete blood panel, intravenous glucose tolerance test (IVGTT), and meal tolerance test. CAD severity was assessed with intravascular ultrasound and histology. [Ca2+]i handling in coronary smooth muscle (CSM) cells was assessed with fura-2 ratiometric imaging.ResultsFasting and post-prandial blood glucose, total cholesterol, and serum triglycerides were elevated in MetS-diabetic swine. This group also exhibited hypoinsulinemia during IVGTT and less pancreatic beta cell mass when compared to lean and MetS-nondiabetic swine. IVUS analysis revealed that MetS-diabetic swine had greater percent wall coverage, percent plaque burden, and calcium index when compared to lean and MetS-nondiabetic swine. Fura-2 imaging of CSM [Ca2+]i revealed that MetS-nondiabetic swine exhibited increased sarcoplasmic reticulum Ca2+ store release and Ca2+ influx through voltage-gated Ca2+ channels compared to lean swine. MetS-diabetic swine exhibited impaired Ca2+ efflux.ConclusionsDiabetes exacerbates coronary atherosclerosis and calcification in Ossabaw miniature swine with MetS, accompanied by progression of [Ca2+]i dysregulation in advanced CAD/CAC. These results recapitulate increased CAD in humans with diabetes and establish Ossabaw miniature swine as an animal model for future MetS/diabetes comorbidity studies.

A factorial design to identify process parameters affecting whole mechanically disrupted rat pancreata in a perfusion bioreactor.

Few studies report whole pancreatic tissue culture, as it is a difficult task using traditional culture methods. Here, a factorial design was used to investigate the singular and combinational effects of flow, dissolved oxygen concentration (D.O.) and pulsation on whole mechanically disrupted rat pancreata in a perfusion bioreactor. Whole rat pancreata were cultured for 72 h under defined bioreactor process conditions. Secreted insulin was measured and histological (haematoxylin and eosin (H&E)) as well as immunofluorescent insulin staining were performed and quantified. The combination of flow and D.O. had the most significant effect on secreted insulin at 5 h and 24 h. The D.O. had the biggest effect on tissue histological quality, and pulsation had the biggest effect on the number of insulin-positive structures. Based on the factorial design analysis, bioreactor conditions using high flow, low D.O., and pulsation were selected to further study glucose-stimulated insulin secretion. Here, mechanically disrupted rat pancreata were cultured for 24 h under these bioreactor conditions and were then challenged with high glucose concentration for 6 h and high glucose + IBMX (an insulin secretagogue) for a further 6 h. These cultures secreted insulin in response to high glucose concentration in the first 6 h, however stimulated-insulin secretion was markedly weaker in response to high glucose concentration + IBMX thereafter. After this bioreactor culture period, higher tissue metabolic activity was found compared to that of non-bioreacted static controls. More insulin- and glucagon-positive structures, and extensive intact endothelial structures were observed compared to non-bioreacted static cultures. H&E staining revealed more intact tissue compared to static cultures. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 34:432-444, 2018.

The effects of addition of coenzyme Q10 to metformin on sirolimus-induced diabetes mellitus.

Background/AimsThis study was performed to determine whether adding coenzyme Q10 (CoQ10) to metformin (MET) has a beneficial effect as a treatment for sirolimus (SRL)-induced diabetes mellitus (DM).MethodsDM was induced in rats by daily treatment with SRL (0.3 mg/kg, subcutaneous) for 28 days, and animals were treated with CoQ10 (20 mg/kg, oral) and MET (250 mg/kg, oral) alone or in combination for the latter 14 days of SRL treatment. The effects of CoQ10 and MET on SRL-induced DM were assessed with the intraperitoneal glucose tolerance test (IPGTT) and by determining plasma insulin concentration and the homeostatic model assessment of insulin resistance (HOMA-R) index. We also evaluated the effect of CoQ10 on pancreatic islet size, apoptosis, oxidative stress, and mitochondria morphology.ResultsIPGTT revealed overt DM in SRL-treated rats. The addition of CoQ10 to MET further improved hyperglycemia, decreased HOMA-R index, and increased plasma insulin concentration compared with the SRL group than MET alone therapy. While SRL treatment induced smaller islets with decreased insulin staining intensity, the combination of CoQ10 and MET significantly improved insulin staining intensity, which was accompanied by a reduction in oxidative stress and apoptosis. In addition, co-treatment of CoQ10 and MET significantly increased the levels of antiperoxidative enzymes in the pancreas islet cells compared with MET. At the subcellular level, addition of CoQ10 to MET improved the average mitochondrial area and insulin granule number.ConclusionsAddition of CoQ10 to MET has a beneficial effect on SRL-induced DM compared to MET alone.

Purification of replicating pancreatic \u03b2-cells for gene expression studies

β-cell proliferation is a rare event in adult pancreatic islets. To study the replication-related β-cell biology we designed a replicating β-cells sorting system for gene expression experiments. Replicating β-cells were identified by EdU incorporation and purified by flow cytometry. For β-cell separation islet cells were sorted by size, granularity and Newport Green fluorescence emission that was combined with emitted fluorescence for EdU-labelled replicating cells sorting. The purity of the resulting sorted populations was evaluated by insulin staining and EdU for β-cell identification and for replicating cells, respectively. Total RNA was isolated from purified cell-sorted populations for gene expression analysis. Cell sorting of dispersed islet cells resulted in 96.2% purity for insulin positivity in the collected β-cell fraction and 100% efficiency of the EdU-based cell separation. RNA integrity was similar between FACS-sorted replicating and quiescent β-cells. Global transcriptome analysis of replicating vs quiescent β-cells showed the expected enrichment of categories related to cell division and DNA replication. Indeed, key genes in the spindle check-point were the most upregulated genes in replicating β-cells. This work provides a method that allows for the isolation of replicating β-cells, a very scarce population in adult pancreatic islets.

Intrapancreatic injection of human bone marrow-derived mesenchymal stem/stromal cells alleviates hyperglycemia and modulates the macrophage state in streptozotocin-induced type 1 diabetic mice

Type 1 diabetes mellitus is a progressive disease caused by the destruction of pancreatic β-cells, resulting in insulin dependency and hyperglycemia. While transplanted bone marrow-derived mesenchymal stem/stromal cells (BMMSCs) have been explored as an alternative therapeutic approach for diseases, the choice of delivery route may be a critical factor determining their sustainability. This study evaluated the effects of intrapancreatic and intravenous injection of human BMMSCs (hBMMSCs) in streptozotocin (STZ)-induced type 1 diabetic mouse model. C57/BL6 mice were intraperitoneally injected with 115 mg/kg STZ on day 0. hBMMSCs (1 × 106 cells) or vehicle were injected into the pancreas or jugular vein on day 7. Intrapancreatic, but not intravenous, hBMMSC injection significantly reduced blood glucose levels on day 28 compared with vehicle injection by the same route. This glucose-lowering effect was not induced by intrapancreatic injection of human fibroblasts as the xenograft control. Intrapancreatically injected fluorescence-labeled hBMMSCs were observed in the intra- and extra-lobular spaces of the pancreas, and intravenously injected cells were in the lung region, although the number of cells mostly decreased within 2 weeks of injection. For hBMMSCs injected twice into the pancreatic region on days 7 and 28, the injected mice had further reduced blood glucose to borderline diabetic levels on day 56. Animals injected with hBMMSCs twice exhibited increases in the plasma insulin level, number and size of islets, insulin-positive proportion of the total pancreas area, and intensity of insulin staining compared with vehicle-injected animals. We found a decrease of Iba1-positive cells in islets and an increase of CD206-positive cells in both the endocrine and exocrine pancreas. The hBMMSC injection also reduced the number of CD40-positive cells merged with glucagon immunoreactions in the islets. These results suggest that intrapancreatic injection may be a better delivery route of hBMMSCs for the treatment of type 1 diabetes mellitus.

Glutamine up-regulates pancreatic sodium-dependent neutral aminoacid transporter-2 and mitigates islets apoptosis in diabetic rats.

Glutamine aminoacid regulates insulin exocytosis from pancreatic β-cells. Liraglutide is a glucagon-like peptide-1 (GLP-1) analogue that has fascinated function in inhibiting β-cell apoptosis and preserving pancreatic β-cell mass. The present study investigated the benefit of adding glutamine to a regimen of liraglutide in diabetic rats focusing on their role in increasing insulin production and upregulation of the expression of sodium-dependent neutral aminoacid transporter-2 (SNAT2). In the present study, diabetes mellitus was induced in rats using streptozotocin (STZ, 50mg/kg, ip). Male rats were allocated into 5 groups, (i) vehicle group, (ii) STZ-diabetic rats, (iii) STZ-diabetic rats treated with liraglutide (150μg/kg, sc), (iv) STZ-diabetic rats treated with glutamine (po) and (v) STZ-diabetic rats treated with a combination of liraglutide and glutamine for four weeks. After finishing the therapeutic courses, the fasting blood glucose value was determined and rats were sacrificed. Pancreases were used for quantification of mRNA expression for SNAT2. Paraffin fixed samples were used for histologic staining and immunohistochemistry for insulin and apoptosis markers (activated caspase-3, BCL2 and BAX). Treatment with liraglutide and/or glutamine enhanced insulin production and hence glycemic control in diabetic male rats with favorable effects on apoptosis markers. Treatment with glutamine and its combination with liraglutide significantly increased pancreatic expression of SNAT2 by approximately 30-35 folds. Addition of glutamine to liraglutide regimen enhances the glycemic control and may have utility in clinical settings.

An In-situ glucose-stimulated insulin secretion assay under perfusion bioreactor conditions.

Perfusion bioreactors, unlike traditional in vitro cell culture systems, offer stringent control of physiological parameters such as pH, flow, temperature, and dissolved oxygen concentration which have been shown to have an impact on cellular behaviour and viability. Due to the relative infancy and the growing interest in these in vitro culture systems, detection methods to monitor cell function under dynamic perfusion bioreactor conditions remains one of the main challenges. In this study, INS-1 cells, a cell line which exhibit glucose-stimulated insulin secretion, were embedded in fibrin and cultured under perfusion bioreactor conditions for 48 h and then exposed to either a high-, or low-glucose concentration for 24 h. These cultures were compared to non-bioreacted controls. Bioreacted cultures exposed to a high-glucose concentration showed the highest glucose-stimulated insulin secretion when compared to those in a low-glucose environment. The stimulation index, a marker for insulin secretion functionality, increased over time. A lower incidence of apoptotic cells was observed in the bioreacted cultures when compared to non-bioreacted ones, as evaluated by a TUNEL assay. Immunofluorescence staining of Ki67 and insulin was performed and showed no differences in the incidence of proliferative cells between conditions (bioreacted and non-bioreacted), where all cells stained positive for insulin. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 33:454-462, 2017.