https://hsci.harvard.edu/files/hsci/files/pagliuca_et_al_cell_2014.pdf

Generation of functional human pancreatic β cells in vitro

Diabetes is a disease characterized by a relative or absolute lack of insulin, leading to hyperglycaemia. There are two main types of diabetes: type 1 diabetes and type 2 diabetes. Type 1 diabetes is due to an autoimmune destruction of the insulin-producing pancreatic beta cells, and type 2 diabetes is caused by insulin resistance coupled by a failure of the beta cell to compensate. Animal models for type 1 diabetes range from animals with spontaneously developing autoimmune diabetes to chemical ablation of the pancreatic beta cells. Type 2 diabetes is modelled in both obese and non-obese animal models with varying degrees of insulin resistance and beta cell failure. This review outlines some of the models currently used in diabetes research. In addition, the use of transgenic and knock-out mouse models is discussed. Ideally, more than one animal model should be used to represent the diversity seen in human diabetic patients.

LINKED ARTICLES

Animal Models

This paper is the latest in a series of publications on the use of animal models in pharmacology research. Readers might be interested in the previous papers.

Robinson V (2009). Less is more: reducing the reliance on animal models for nausea and vomiting research.

Holmes AM, Rudd JA, Tattersall FD, Aziz Q, Andrews PLR (2009). Opportunities for the replacement of animals in the study of nausea and vomiting.

Giacomotto J and Segalat L (2010). High-throughput screening and small animal models, where are we?

McGrath JC, Drummond GB, McLachlan EM, Kilkenny C, Wainwright CL (2010). Guidelines for reporting experiments involving animals: the ARRIVE guidelines.

Kilkenny C, Browne W, Cuthill IC, Emerson M, Altman DG (2010). The ARRIVE guidelines.

Emerson M (2010). Refinement, reduction and replacement approaches to in vivo cardiovascular research.

Berge O-G (2011). Predictive validity of behavioural animal models for chronic pain.

Vickers SP, Jackson HC and Cheetham SC (2011). The utility of animal models to evaluate novel anti-obesity agents.

Percie du Sert N, Holmes AM, Wallis R, Andrews PLR (2012). Predicting the emetic liability of novel chemical entities: a comparative study.

The complete series including future publications, as they occur, can be found at http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1476-5381/homepage/animal_models.htm.

https://bpspubs.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1476-5381.2012.01911.x

The use of animal models in diabetes research

Multiple small injections of streptozotocin in mice produce pancreatic insulitis, with progression to nearly complete beta cell destruction and diabetes mellitus. The timing and appearance of the inflammatory islet lesions suggest but do not prove that streptozotocin acts by initiating a cell-mediated immune reaction. Ultrastructural evidence of abundant type C viruses within beta cells of treated mice suggests that streptozotocin may activate murine leukemia virus in vivo in susceptible hosts.

http://science.sciencemag.org/content/sci/193/4251/415.full.pdf

Streptozotocin-induced pancreatic insulitis: new model of diabetes mellitus.

Brefeldin A's effects on endosomes, lysosomes, and the TGN suggest a general mechanism for regulating organelle structure and membrane traffic

Pancreatic β-cell dysfunction plays an important role in the pathogenesis of both type 1 and type 2 diabetes. Insulin, which is produced in β-cells, is a critical regulator of metabolism. Insulin is synthesized as preproinsulin and processed to proinsulin. Proinsulin is then converted to insulin and C-peptide and stored in secretary granules awaiting release on demand. Insulin synthesis is regulated at both the transcriptional and translational level. The cis-acting sequences within the 5' flanking region and trans-activators including paired box gene 6 (PAX6), pancreatic and duodenal homeobox- 1(PDX-1), MafA, and β-2/Neurogenic differentiation 1 (NeuroD1) regulate insulin transcription, while the stability of preproinsulin mRNA and its untranslated regions control protein translation. Insulin secretion involves a sequence of events in β-cells that lead to fusion of secretory granules with the plasma membrane. Insulin is secreted primarily in response to glucose, while other nutrients such as free fatty acids and amino acids can augment glucose-induced insulin secretion. In addition, various hormones, such as melatonin, estrogen, leptin, growth hormone, and glucagon like peptide-1 also regulate insulin secretion. Thus, the β-cell is a metabolic hub in the body, connecting nutrient metabolism and the endocrine system. Although an increase in intracellular [Ca2+] is the primary insulin secretary signal, cAMP signaling- dependent mechanisms are also critical in the regulation of insulin secretion. This article reviews current knowledge on how β-cells synthesize and secrete insulin. In addition, this review presents evidence that genetic and environmental factors can lead to hyperglycemia, dyslipidemia, inflammation, and autoimmunity, resulting in β-cell dysfunction, thereby triggering the pathogenesis of diabetes.

Regulation of insulin synthesis and secretion and pancreatic Beta-cell dysfunction in diabetes

The developing pancreases of twenty human embryos and fetuses, 8–23 weeks gestational age, were obtained under conditions optimum for cellular preservation and studied by light and electron microscopy. Primitive pancreatic tubules were the only epithelial structures present at 8 and 8.5 weeks. Alpha cells were first identified at 9 weeks, followed by delta and subsequently beta cells at 10.5 weeks. Endocrine cell progenitors, mixed endocrine cells, or mixed exocrine endocrine cells were not identified. Although potential sampling errors preclude a definitive recitation of the order of islet cell appearance, the alpha and delta cells are numerically the predominant pancreatic endocrine cells during early human embryogenesis. The observation of frequent, well-preserved delta cells and the identification of one undergoing mitotic division support their legitimacy as an independent cell type. Cytoplasmic glycogen was present in primitive tubular cells and differentiated exocrine cells but was excluded from endocrine cells. Other endocrine cells tentatively identified in the developing human pancreas are serotonin, gastrin, epinephrine and norepinephrine cells.

Embryogenesis of the human pancreatic islets: a light and electron microscopic study.

Monolayer cell culture of neonatal rat pancreas: an ultrastructural and biochemical study of functioning endocrine cells.

Kilham rat virus (KRV) infection of BB/Wor diabetes-resistant (DR) RT1(u) rats induces autoimmune diabetes without direct cytolytic infection of pancreatic beta-cells and is a new model of virus-induced IDDM. To investigate genetic susceptibility to KRV-induced diabetes, major histocompatibility complex congenic and other inbred rats were infected with the virus and studied for the appearance of diabetes and insulitis. KRV infection alone induced insulitis, selective beta-cell necrosis, and diabetes in BB/Wor DR and LEW1.WR1 (RT1 A(u) B/D(u) C(a)) but not other rats. Thus, KRV, an environmentally ubiquitous rat parvovirus, can precipitate autoimmune diabetes in rats that are not susceptible to spontaneous diabetes. If rats are injected with poly(I.C) immediately before KRV infection, diabetes frequency increases to >90% in BB/Wor DR and LEW1.WR1 rats, and PVG.RT1(u) rats are converted from KRV-resistant to KRV-susceptible status. Susceptibility to KRV-induced diabetes thus requires the presence of class I A(u) and class II B/D(u) gene products, which are shared by DR, LEW1.WR1, and PVG.RT1(u) rats. The RT1(u) haplotype is not sufficient for susceptibility, however, because while WF rats are RT1(u), they resist KRV-induced diabetes. If rats are depleted of RT6.1+ regulatory T-cells before KRV infection, the frequency of diabetes is dramatically increased in DR and LEW1.WR1, but not PVG.RT1(u) or other rats. These data confirm a regulatory role of RT6.1+ T-cells in diabetes induction, but indicate that they may not operate as such in all rat strains. KRV-induced diabetes is T-cell-mediated: DR and LEW1.WR1 rats are protected from diabetes by treatment with monoclonal antibodies directed against alpha beta T-cell receptor (TCR)+, CD5+, and CD8+ T-cells. Concanavalin A-activated spleen cells from KRV-infected DR rats adoptively transfer diabetes and insulitis into class II(u) compatible rats, suggesting that KRV infection of susceptible rats leads to the activation of diabetogenic class II(u) restricted T-cells. The ability of a common rat virus to initiate IDDM in multiple strains of rats strengthens the possibility that viruses may also initiate IDDM in human populations.

Kilham rat triggers T-cell-dependent autoimmune diabetes in multiple strains of rat.

 Monolayer culture of pancreatic cells from newborn rats has been shown to yield ultrastructurally normal endocrine cells, virtual absence of differentiated exocrine cells, and the maintenance of the capacity to synthesize immuno-reactive insulin (IRI) and glucagon (ERG) Such a preparation has potential advantages for the study of mechanisms of hormone synthesis and release Therefore, a survey of factors influencing hormone content and release from cultured cells was undertaken The following general features were demonstrated: (1) highly reproducible responses within a given preparation of cells despite (2) some variations of absolute hormone content and release between preparations, (3) suitability for preparing sufficient quantities of cells to permit the simultaneous comparison of several factors within a given preparation, and (4) persistence of physiological responses to known modulators of IRI and IRG release Thus, IRI release was stimulated in concentration-related fashion by glucose Amino acids, tolbutamide and glucagon augmented release, and 2-deoxy-D-glucose, mannoheptulose and diazoxide inhibited glucose-induced release Epinephrine inhibited glucose-induced IRI release through stimulation of an α-adrenergic receptor mechanism, and the presence of probable β-receptor stimulation of release was also demonstrated Agents affecting the microtubular-microfilamentous system exerted effecte similar to those demonstrated in other preparations Ouabain, as well as the absence or augmented potassium in the medium increased IRI release in the presence of non-stimulatory 275 mM glucose, whereas absence of calcium inhibited the response to 11 mM glucose without affecting baseline, non-stimulated release IRG release was shown to be inversely related to the glucose concentration in the medium It was stimulated by epinephrine, arginine, alanine, lactate and pyruvate, and inhibited by β-hydroxybutyrate Diazoxide alone had no effect on IRG release The monolayer culture employed in these studies provides a convenient, reproducible system for the further study of adult-type IRI and IRG secretory behaviour In addition to acute or short-term regulation it may be especially suited for the study of long-term modulating effects during the culture period

Insulin and glucagon release from monolayer cell cultures of pancreas from newborn rats.

The spontaneously diabetic BioBreeding/Worcester (BB/W) rat was used to examine the role of glycemie control in the pathogenesis of diabetic glomerulopathy and proteinuria. Nondiabetic BB/W rats (group 1) were compared with moderately (group 2) and severely (group 3) hyperglycemie diabetic animals of similar age. Urinary protein excretion and morphometric measurements of glomerular basement membrane (GBM) width and mesangial area were performed after 4, 8, and 12 mo of study. At 4 mo, urinary protein excretion both in group 2 (9.3 ± 0.7 mg/24 h) and group 3 (24.8 ± 1.98 mg/24 h) exceeded that in group 1 (5.4 ± 0.6 mg/24 h; P P GBM width in both diabetic groups (168.8 ± 2.4 and 165.7 ± 2.2 nm, groups 2 and 3, respectively) exceeded that in group 1 (148.3 ± 3.8 nm; P In the spontaneously diabetic BB/W rat, poor glycemie control contributes to both proteinuria and GBM widening but apparently does not cause mesangial expansion. Proteinuria and GBM widening may either be interdependent or related to a common third factor in the diabetic milieu.

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Papers

Embryogenesis of the human pancreatic islets: a light and electron microscopic study.

Monolayer cell culture of neonatal rat pancreas: an ultrastructural and biochemical study of functioning endocrine cells.

Kilham rat triggers T-cell-dependent autoimmune diabetes in multiple strains of rat.

Insulin and glucagon release from monolayer cell cultures of pancreas from newborn rats.

Glomerulopathy in spontaneously diabetic rat. Impact of glycemic control.