scholarly journals Effect of prolonged in vitro exposure to high glucose on neonatal porcine pancreatic islets

2006 ◽  
Vol 191 (1) ◽  
pp. 37-44 ◽  
Author(s):  
George Harb ◽  
Gregory S Korbutt
Keyword(s):  
High Glucose ◽  
Prolonged Exposure ◽  
Islet Cells ◽  
Cell Mass ◽  
Β Cells ◽  
Β Cell ◽  
Porcine Islets ◽  
Clinical Islet Transplantation ◽  
Neonatal Porcine Islets

Prolonged exposure to high glucose can influence the function, growth, and survival of pancreatic β-cells. In this study, we examine the effects of prolonged in vitro exposure to high glucose on neonatal porcine β-cells, a potentially useful source of insulin-producing cells for clinical islet transplantation. Neonatal porcine islets were prepared by culturing collagenase-digested pancreases for 1 week in 5.6 mM glucose, followed by an additional week in either 5.6, 10.0, or 28.0 mM glucose. An additional 2 days of culture in 5.6 mM glucose followed for recovery from high glucose. The 7-day culture period in 28.0 mM glucose failed to irreversibly impair glucose responsiveness and also caused a modest increase in β-cell mass. Immunostaining revealed that precursor cell differentiation was responsible for the increase in β-cell mass rather than β-cell proliferation. Islet cell survival was also assessed by a DNA fragmentation assay (TUNEL stain) to determine β-cell susceptibility to apoptosis after exposure to high glucose. Interestingly, although the total number of apoptotic islet cells did not drastically change after a week of culture in either 5.6, 10.0, or 28.0 mM glucose (25% TUNEL-positive), neither did the percentage of apoptotic β-cells. These encouraging results further support the use of neonatal porcine islets for clinical transplantation because of their ability to resist the cytotoxic effects of high glucose on islet function and survival.

Accelerated Functional Maturation of Isolated Neonatal Porcine Cell Clusters: In Vitro and In Vivo Results in NOD Mice

2005 ◽  
Vol 14 (5) ◽  
pp. 249-261 ◽  
Author(s):  
Giovanni Luca ◽  
Claudio Nastruzzi ◽  
Mario Calvitti ◽  
Ennio Becchetti ◽  
Tiziano Baroni ◽  
...  
Keyword(s):  
Sertoli Cells ◽  
Time Lag ◽  
Cell Mass ◽  
Nod Mice ◽  
Β Cell ◽  
Cell Clusters ◽  
Porcine Islets ◽  
Neonatal Porcine Islets

Neonatal porcine cell clusters (NPCCs) might replace human for transplant in patients with type 1 diabetes mellitus (T1DM). However, these islets are not immediately functional, due to their incomplete maturation/differentiation. We then have addressed: 1) to assess whether in vitro coculture of islets with homologous Sertoli cells (SC) would shorten NPCCs' functional time lag, by accelerating the β-cell biological maturation/differentiation; 2) to evaluate metabolic outcome of the SC preincubated, and microencapsulated NPCCs, upon graft into spontaneously diabetic NOD mice. The islets, isolated from <3 day piglets, were examined in terms of morphology/viability/function and final yield. SC effects on the islet maturation pathways, both in vitro and in vivo, upon microencapsulation in alginate/poly-L-ornithine, and intraperitoneal graft into spontaneously diabetic NOD mice were determined. Double fluorescence immunolabeling showed increase in β-cell mass for SC+ neonatal porcine islets versus islets alone. In vitro insulin release in response to glucose, as well as mRNA insulin expression, were significantly higher for SC+ neonatal porcine islets compared with control, thereby confirming SC-induced increase in viable and functional β-cell mass. Graft of microencapsulated SC+ neonatal porcine islets versus encapsulated islets alone resulted in significantly longer remission of hyperglycemia in NOD mice. We have preliminarily shown that the in vitro NPCCs' maturation time lag can dramatically be curtailed by coincubating these islets with SC. Graft of microencapsulated neonatal porcine islets, precultured in Sertoli cells, has been proven successful in correcting hyperglycemia in stringent animal model of spontaneous diabetes.

Harnessing immune cells to enhance β-cell mass in type 1 diabetes

2016 ◽  
Vol 64 (1) ◽  
pp. 14-20 ◽  
Author(s):  
Ercument Dirice ◽  
Rohit N Kulkarni
Keyword(s):  
Type 1 Diabetes ◽  
Mononuclear Cells ◽  
Islet Cells ◽  
Cell Mass ◽  
Cell Loss ◽  
Cell Types ◽  
Β Cells ◽  
Β Cell ◽  
Autoimmune Attack

Type 1 diabetes is characterized by early β-cell loss leading to insulin dependence in virtually all patients with the disease in order to maintain glucose homeostasis. Most studies over the past few decades have focused on limiting the autoimmune attack on the β cells. However, emerging data from patients with long-standing diabetes who continue to harbor functional insulin-producing cells in their diseased pancreas have prompted scientists to examine whether proliferation of existing β cells can be enhanced to promote better glycemic control. In support of this concept, several studies indicate that mononuclear cells that infiltrate the islets have the capacity to trigger proliferation of islet cells including β cells. These observations indicate the exciting possibility of identifying those mononuclear cell types and their soluble factors and harnessing their ability to promote β-cell growth concomitant with autoimmune therapy to prevent the onset and/or halt the progression of the disease.

scholarly journals Increased Susceptibility to Streptozotocin-Induced β-Cell Apoptosis and Delayed Autoimmune Diabetes in Alkylpurine- DNA-N-Glycosylase-Deficient Mice

2001 ◽  
Vol 21 (16) ◽  
pp. 5605-5613 ◽  
Author(s):  
John W. Cardinal ◽  
Geoffrey P. Margison ◽  
Kurt J. Mynett ◽  
Allen P. Yates ◽  
Donald P. Cameron ◽  
...  
Keyword(s):  
Islet Cells ◽  
Excision Repair ◽  
Autoimmune Diabetes ◽  
Atp Depletion ◽  
Cell Necrosis ◽  
Β Cells ◽  
Β Cell ◽  
Autoimmune Reaction ◽  
Strand Breaks

ABSTRACT Type 1 diabetes is thought to occur as a result of the loss of insulin-producing pancreatic β cells by an environmentally triggered autoimmune reaction. In rodent models of diabetes, streptozotocin (STZ), a genotoxic methylating agent that is targeted to the β cells, is used to trigger the initial cell death. High single doses of STZ cause extensive β-cell necrosis, while multiple low doses induce limited apoptosis, which elicits an autoimmune reaction that eliminates the remaining cells. We now show that in mice lacking the DNA repair enzyme alkylpurine-DNA-N-glycosylase (APNG), β-cell necrosis was markedly attenuated after a single dose of STZ. This is most probably due to the reduction in the frequency of base excision repair-induced strand breaks and the consequent activation of poly(ADP-ribose) polymerase (PARP), which results in catastrophic ATP depletion and cell necrosis. Indeed, PARP activity was not induced in APNG−/− islet cells following treatment with STZ in vitro. However, 48 h after STZ treatment, there was a peak of apoptosis in the β cells of APNG−/− mice. Apoptosis was not observed in PARP-inhibited APNG+/+ mice, suggesting that apoptotic pathways are activated in the absence of significant numbers of DNA strand breaks. Interestingly, STZ-treated APNG−/− mice succumbed to diabetes 8 months after treatment, in contrast to previous work with PARP inhibitors, where a high incidence of β-cell tumors was observed. In the multiple-low-dose model, STZ induced diabetes in both APNG−/− and APNG+/+ mice; however, the initial peak of apoptosis was 2.5-fold greater in the APNG−/− mice. We conclude that APNG substrates are diabetogenic but by different mechanisms according to the status of APNG activity.

scholarly journals Perilipin2 down-regulation in β cells impairs insulin secretion under nutritional stress and damages mitochondria

2020 ◽  
Author(s):  
Akansha Mishra ◽  
Siming Liu ◽  
Joseph Promes ◽  
Mikako Harata ◽  
William Sivitz ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Cell Function ◽  
Islet Cells ◽  
Cell Metabolism ◽  
Nutritional Stress ◽  
Β Cells ◽  
Β Cell ◽  
Down Regulation

Perilipin 2 (PLIN2) is the lipid droplet (LD) protein in β cells that increases under nutritional stress. Down-regulation of PLIN2 is often sufficient to reduce LD accumulation. To determine whether PLIN2 positively or negatively affects β cell function under nutritional stress, PLIN2 was down-regulated in mouse β cells, INS1 cells, and human islet cells. β cell specific deletion of PLIN2 in mice on a high fat diet reduced glucose-stimulated insulin secretion (GSIS) in vivo and in vitro. Down-regulation of PLIN2 in INS1 cells blunted GSIS after 24 h incubation with 0.2 mM palmitic acids. Down-regulation of PLIN2 in human pseudoislets cultured at 5.6 mM glucose impaired both phases of GSIS, indicating that PLIN2 is critical for GSIS. Down-regulation of PLIN2 decreased specific OXPHOS proteins in all three models and reduced oxygen consumption rates in INS1 cells and mouse islets. Moreover, we found that PLIN2 deficient INS1 cells increased the distribution of a fluorescent oleic acid analog to mitochondria and showed signs of mitochondrial stress as indicated by susceptibility to fragmentation and alterations of acyl-carnitines and glucose metabolites. Collectively, PLIN2 in β cells have an important role in preserving insulin secretion, β cell metabolism and mitochondrial function under nutritional stress.

scholarly journals Molecular regulation of pancreatic β-cell mass development, maintenance, and expansion

2007 ◽  
Vol 38 (2) ◽  
pp. 193-206 ◽  
Author(s):  
Amanda M Ackermann ◽  
Maureen Gannon
Keyword(s):  
Cell Differentiation ◽  
Cell Mass ◽  
Β Cells ◽  
Β Cell ◽  
Pancreatic Development ◽  
Proliferation And Apoptosis ◽  
Patients With Diabetes ◽  
Mass Development ◽  
Differentiation And Proliferation

Pancreatic β-cells are responsible for producing all of the insulin required by an organism to maintain glucose homeostasis. Defects in development, maintenance, or expansion of β-cell mass can result in impaired glucose metabolism and diabetes. Thus, identifying the molecular regulators of these processes may provide new therapeutic targets for diabetes. Additionally, understanding the processes of β-cell differentiation and proliferation may allow for in vitro cultivation of β-cells in sufficient amounts to be transplanted into patients with diabetes. This review addresses many of the transcription factors and signaling pathways that play a role in early pancreatic development and endocrine cell (specifically β-cell) differentiation, conditions that influence β-cell mass development and molecular regulators of β-cell proliferation and apoptosis that are responsible for maintaining and expanding β-cell mass.

Sustained exposure of toxically damaged mouse pancreatic islets to high glucose does not increase β-cell dysfunction

1989 ◽  
Vol 123 (1) ◽  
pp. 47-51 ◽  
Author(s):  
D. L. Eizirik ◽  
S. Sandler
Keyword(s):  
Pancreatic Islets ◽  
Insulin Release ◽  
High Glucose ◽  
Β Cells ◽  
Β Cell ◽  
Glucose Stimulation ◽  
Cell Dysfunction ◽  
Mouse Pancreatic Islets ◽  
Insulin Secretory Response

ABSTRACT The aim of this study was to clarify whether prolonged in-vitro exposure of either normal or damaged β cells to a high glucose environment can be toxic to these cells. For this purpose NMRI mice were injected intravenously with a diabetogenic dose of streptozotocin (SZ; 160 mg/kg) or vehicle alone (controls). Their islets were isolated 15 min after the injection and subsequently maintained in culture for 21 days in the presence of 11·1 or 28 mmol glucose/l. After this period, during acute glucose stimulation, the control islets showed a marked increase in their insulin release in response to a high glucose stimulus. In the SZ-exposed islets there was a decrease in DNA and insulin contents, and a deficient insulin secretory response to glucose. However, in the SZ-damaged islets as well as in the control islets, culture with 28 mmol glucose/l compared with 11·1 mmol glucose/l did not impair islet retrieval after culture, islet DNA content or glucose-induced insulin release. Thus, the degree of damage was similar in the SZ-treated islets cultured at the two concentrations of glucose. These results suggest that glucose is not toxic to normal or damaged mouse pancreatic islets over a prolonged period in tissue culture. Journal of Endocrinology (1989) 123, 47–51

scholarly journals Protection of pancreatic β-cells by exendin-4 may involve the reduction of endoplasmic reticulum stress; in vivo and in vitro studies

2007 ◽  
Vol 193 (1) ◽  
pp. 65-74 ◽  
Author(s):  
Shin Tsunekawa ◽  
Naoki Yamamoto ◽  
Katsura Tsukamoto ◽  
Yuji Itoh ◽  
Yukiko Kaneko ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Death ◽  
Er Stress ◽  
Islet Cells ◽  
Binding Protein ◽  
Β Cells ◽  
Β Cell ◽  
Pancreatic Β Cells

The aim of this study was to investigate the in vivo and in vitro effects of exendin-4, a potent glucagon-like peptide 1 agonist, on the protection of the pancreatic β-cells against their cell death. In in vivo experiments, we used β-cell-specific calmodulin-overexpressing mice where massive apoptosis takes place in their β-cells, and we examined the effects of chronic treatment with exendin-4. Chronic and s.c. administration of exendin-4 reduced hyperglycemia. The treatment caused significant increases of the insulin contents of the pancreas and islets, and retained the insulin-positive area. Dispersed transgenic islet cells lived only shortly, and several endoplasmic reticulum (ER) stress-related molecules such as immunoglobulin-binding protein (Bip), inositol-requiring enzyme-1α, X-box-binding protein-1 (XBP-1), RNA-activated protein kinase-like endoplasmic reticulum kinase, activating transcription factor-4, and C/EBP-homologous protein (CHOP) were more expressed in the transgenic islets. We also found that the spliced form of XBP-1, a marker of ER stress, was also increased in β-cell-specific calmodulin-overexpressing transgenic islets. In the quantitative real-time PCR analyses, the expression levels of Bip and CHOP were reduced in the islets from the transgenic mice treated with exendin-4. These findings suggest that excess of ER stress occurs in the transgenic β-cells, and the suppression of ER stress and resultant protection against cell death may be involved in the anti-diabetic effects of exendin-4.

scholarly journals Metformin Preserves β-Cell Compensation in Insulin Secretion and Mass Expansion in Prediabetic Nile Rats

2021 ◽  
Vol 22 (1) ◽  
pp. 421
Author(s):  
Hui Huang ◽  
Bradi R. Lorenz ◽  
Paula Horn Zelmanovitz ◽  
Catherine B. Chan
Keyword(s):  
Insulin Secretion ◽  
Cell Function ◽  
Cell Mass ◽  
Metformin Treatment ◽  
Β Cells ◽  
Β Cell ◽  
Β Cell Function ◽  
Glucose Output ◽  
Mass Expansion

Prediabetes is a high-risk condition for type 2 diabetes (T2D). Pancreatic β-cells adapt to impaired glucose regulation in prediabetes by increasing insulin secretion and β-cell mass expansion. In people with prediabetes, metformin has been shown to prevent prediabetes conversion to diabetes. However, emerging evidence indicates that metformin has negative effects on β-cell function and survival. Our previous study established the Nile rat (NR) as a model for prediabetes, recapitulating characteristics of human β-cell compensation in function and mass expansion. In this study, we investigated the action of metformin on β-cells in vivo and in vitro. A 7-week metformin treatment improved glucose tolerance by reducing hepatic glucose output and enhancing insulin secretion. Although high-dose metformin inhibited β-cell glucose-stimulated insulin secretion in vitro, stimulation of β-cell insulin secretion was preserved in metformin-treated NRs via an indirect mechanism. Moreover, β-cells in NRs receiving metformin exhibited increased endoplasmic reticulum (ER) chaperones and alleviated apoptotic unfold protein response (UPR) without changes in the expression of cell identity genes. Additionally, metformin did not suppress β-cell mass compensation or proliferation. Taken together, despite the conflicting role indicated by in vitro studies, administration of metformin does not exert a negative effect on β-cell function or cell mass and, instead, early metformin treatment may help protect β-cells from exhaustion and decompensation.

Staining and in Vitro Toxicity of Dithizone with Canine, Porcine, and Bovine Islets

1994 ◽  
Vol 3 (4) ◽  
pp. 299-306 ◽  
Author(s):  
Samuel A. Clark ◽  
Kermit M. Borland ◽  
Sandra D. Sherman ◽  
Thelma C. Rusack ◽  
William L. Chick
Keyword(s):  
Concentration Dependence ◽  
Prolonged Exposure ◽  
Islet Cells ◽  
Toxic Effects ◽  
Insulin Content ◽  
Lower Percentage ◽  
In Vitro Toxicity ◽  
Porcine Islets

Dithizone (DTZ) is a recognized diabetogenic agent in vivo, and a supravital stain commonly used for identification of islets to be used for transplantation. In the present studies, we compared DTZ staining of freshly isolated and cultured canine, bovine, and porcine islets, and the effect of DTZ on the function and viability of islets. Incubation with DTZ resulted in staining of canine and porcine islets, but no discernible staining with bovine islets. Insulin content of porcine, canine, and bovine islet was 2.0 ± 0.2, 2.2 ± 0.3, and 1.9 ± 0.2 mU/EIN, indicating a lack of correspondence of DTZ staining and insulin content. Seven days of culture with canine islets resulted in ≥50% reduction of DTZ stained cells. Exposure to DTZ at 50 μg/mL resulted in a maximal number of stained cells in preparations of purified islets (80-85%; counted after dispersion), a lower percentage of cells stained faintly at 20 μg/mL (50-55%), with no discernible staining at 10 μg/mL. Prolonged exposure of islets (4-48 h) to 20 μg/mL DTZ led to reduced insulin secretion and islet cell death. Incubation of canine or porcine islets with 100 μg/mL of DTZ for 0.5 h resulted in a dramatic loss of viability and diminished insulin secretory function, which was not reversed with continued culture. The concentration dependence of toxic effects paralleled the concentration dependence of cellular staining. The minimally effective staining concentration (20 μg/mL) also resulted in a loss of viability. An additional assessment of DTZ toxicity was made using the RIN-38 β-cell line, which shows no discernible staining with DTZ. A 1 h exposure to dithizone resulted in a dose-dependent loss of viable RIN-38 cells. We conclude first, that DTZ is cytotoxic to islet cells in vitro, at concentrations used for islet staining. Although the toxicity of DTZ appears to be related to its staining properties, high concentrations have toxic effects that are unrelated to staining properties. We propose that cellular accumulation of DTZ (staining), produces toxicity by concentrating DTZ to toxic levels. Secondly, we conclude that DTZ does not stain islets of all species, despite the equivalent insulin content.

scholarly journals Mitogen-Inducible Gene 6 Triggers Apoptosis and Exacerbates ER Stress-Induced β-Cell Death

2013 ◽  
Vol 27 (1) ◽  
pp. 162-171 ◽  
Author(s):  
Yi-Chun Chen ◽  
E. Scott Colvin ◽  
Bernhard F. Maier ◽  
Raghavendra G. Mirmira ◽  
Patrick T. Fueger
Keyword(s):  
Cell Death ◽  
Er Stress ◽  
Caspase 3 ◽  
Cell Mass ◽  
Growth Factor Receptor ◽  
Protein Translation ◽  
Β Cells ◽  
Β Cell ◽  
Inducible Gene

The increased insulin secretory burden placed on pancreatic β-cells during obesity and insulin resistance can ultimately lead to β-cell dysfunction and death and the development of type 2 diabetes. Mitogen-inducible gene 6 (Mig6) is a cellular stress-responsive protein that can negatively regulate the duration and intensity of epidermal growth factor receptor signaling and has been classically viewed as a molecular brake for proliferation. In this study, we used Mig6 heterozygous knockout mice (Mig6+/−) to study the role of Mig6 in regulating β-cell proliferation and survival. Surprisingly, the proliferation rate of Mig6+/− pancreatic islets was lower than wild-type islets despite having comparable β-cell mass and glucose tolerance. We thus speculated that Mig6 regulates cellular death. Using adenoviral vectors to overexpress or knockdown Mig6, we found that caspase 3 activation during apoptosis was dependent on the level of Mig6. Interestingly, Mig6 expression was induced during endoplasmic reticulum (ER) stress, and its protein levels were maintained throughout ER stress. Using polyribosomal profiling, we identified that Mig6 protein translation was maintained, whereas the global protein translation was inhibited during ER stress. In addition, Mig6 overexpression exacerbated ER stress-induced caspase 3 activation in vitro. In conclusion, Mig6 is transcriptionally up-regulated and resistant to global translational inhibition during stressed conditions in β-cells and mediates apoptosis in the form of caspase 3 activation. The sustained production of Mig6 protein exacerbates ER stress-induced β-cell death. Thus, preventing the induction, translation, and/or function of Mig6 is warranted for increasing β-cell survival.

Sign in / Sign up

Export Citation Format

Share Document