We would like to thank Renee L. Pasker and Harpreet K. Brar for expert technical assistance on the protocols described in this work. Furthermore, we would like to acknowledge the mentoring of Christopher B. Newgard at Duke University and Alan D. Attie at the University of Wisconsin-Madison, along with the support of their laboratory members, which allowed us the time and support necessary to optimize the described protocols. In particular, we thank Hans Hohmeier, Danhong Lu, and Helena Winfield in the Newgard Laboratory and Mary Rabaglia in the Attie Laboratory for productive discussions and advice. This work was supported by NIH grant DK080845 and Juvenile Diabetes 594 
Research Foundation grant 17-2011-608 (to M.E.K.)

<ol>
	<li>Cryer, P. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hypoglycaemia:+the+limiting+factor+in+the+glycaemic+management+of+Type+I+and+Type+II+diabetes.">Hypoglycaemia: the limiting factor in the glycaemic management of Type I and Type II diabetes.</a> Diabetologia. 45, 937-948 (2002).</li><li>Alberti, K. G., Zimmet, P. Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Definition,+diagnosis+and+classification+of+diabetes+mellitus+and+its+complications.+Part+1:+diagnosis+and+classification+of+diabetes+mellitus+provisional+report+of+a+WHO+consultation.">Definition, diagnosis and classification of diabetes mellitus and its complications. Part 1: diagnosis and classification of diabetes mellitus provisional report of a WHO consultation.</a> Diabet Med. 15, 539-553 (1998).</li><li>Muoio, D. 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S., Rorsman, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Long-term+exposure+of+mouse+pancreatic+islets+to+oleate+or+palmitate+results+in+reduced+glucose+induced+somatostatin+and+oversecretion+of+glucagon.">Long-term exposure of mouse pancreatic islets to oleate or palmitate results in reduced glucose induced somatostatin and oversecretion of glucagon.</a> Diabetologia. 51, 1689-1693 (2008).</li><li>Fueger, P. T., Hernandez, A. M., Chen, Y. C., Colvin, E. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Assessing+Replication+and+Beta+Cell+Function+in+Adenovirally-transduced+Isolated+Rodent+Islets.">Assessing Replication and Beta Cell Function in Adenovirally-transduced Isolated Rodent Islets.</a> J Vis Exp. , (2012).</li><li>Szot, G. L., Koudria, P., Bluestone, J. 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Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Global+estimates+of+the+prevalence+of+diabetes+for+2010+and+2030.">Global estimates of the prevalence of diabetes for 2010 and 2030.</a> Diabetes Res Clin Pract. 87, 4-14 (2010).</li><li>Kirstetter, P., Lagneau, F., Lucas, O., Krupa, Y., Marty, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Role+of+endothelium+in+the+modulation+of+isoflurane-induced+vasodilatation+in+rat+thoracic+aorta.">Role of endothelium in the modulation of isoflurane-induced vasodilatation in rat thoracic aorta.</a> Br J Anaesth. 79, 84-87 (1997).</li><li>Brown, E. T., Umino, Y., Loi, T., Solessio, E., Barlow, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Anesthesia+can+cause+sustained+hyperglycemia+in+C57/BL6J+mice.">Anesthesia can cause sustained hyperglycemia in C57/BL6J mice.</a> Vis Neurosci. 22, 615-618 (2005).</li><li>Vaupel, D. B., McCoun, D., Cone, E. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Phencyclidine+analogs+and+precursors:+rotarod+and+lethal+dose+studies+in+the+mouse.">Phencyclidine analogs and precursors: rotarod and lethal dose studies in the mouse.</a> J Pharmacol Exp Ther. 230, 20-27 (1984).</li><li>Davis, D. 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Authors have nothing to disclose.

With the prevalence of diabetes projected to affect 7.7% of the world&#8217;s population, the requirement of novel research techniques is imperative to both understand and treat diabetes18. The present islet isolation is a well-established protocol used for in vitro experimentation and has been presented previously with slight modifications11,14,16. Although insulin secretion is a common downstream application for isolated islets, focusing on upstream constituents, such as cAMP, may help de...

The strict maintenance of euglycemia is imperative to prevent morbidities such as neuropathy, nephropathy, and retinopathy, which are all hallmarks of the pathology of uncontrolled type 1 and 2 diabetes1. Reduced &#946;-cell function and mass in both type 1 and 2 diabetes perturb blood glucose concentrations2. Whereas immune-mediated type 1 diabetes results from a devastating loss of insulin-producing &#946;-cells, impaired &#946;-cell insulin secretion and peripheral insulin signaling in type 2 diabetes together promote hyperglycemia, dyslipidemia, and increased hepatic glucose production, which eventually results in both loss of &#946;-cell mass and insulin secretory capacity from individual &#946;-cells3. Understanding the underlying &#946;-cell mechanisms in the progression of type 1 and 2 diabetes will hopefully give rise to novel therapies to prevent and treat these diseases.
In vitro tissue culture models, such as the INS-1 and MIN6 immortalized &#946;-cell lines, can be useful tools for understanding specific &#946;-cell functions. However, the interactions among the different cell types within the islet may themselves regulate &#946;-cell function. For example, the paracrine influence of glucagon (released from &#945;-cells) and somatostatin (released from &#948;-cells) in increasing and decreasing insulin secretion, respectively, demonstrates the importance of cell cell proximity in the endocrine response4. Moreover, gap junctions between &#946;-cells potentiate the release of insulin5. Furthermore, although strides have been made in generating insulinoma lines that better replicated the physiological response of isolated islets to glucose (e.g., the INS-1- derived 832/13 and 832/3 cell lines), their glucose responsiveness still differs from normal rat islets6,7. Moreover, the response of these clonal insulinoma cell lines to glucagon-like peptide-1 (GLP-1) agonists can differ dramatically from one another, as well as from normal islets6. Therefore, immortalized cell lines may not represent the best model for assaying agents that impact on cAMP production.
In contrast to the insulinoma-derived cell lines, studying &#946;-cell function solely in whole animal models offers its own set of complications. One of the biggest challenges in working with endocrine tissue is measuring the precise concentration of hormone released. Specifically, the liver plays a major role metabolizing insulin, and the pancreas blood flow goes directly to the liver. Thus, a plasma insulin measurement may not accurately portray the amounts of insulin being secreted from the pancreas itself or the impact of different treatments on the rate of insulin secretion8. Furthermore, renal metabolism of glucagon may limit the reliability of glucagon output from islet &#945;-cells9. Therefore, isolating primary mouse islets for in vitro experimentation provides a more precise understanding of how the islet is responding to specific stimuli to complement measurements made in vivo.
The present protocol for the isolation of mouse islets is a well-established protocol used by a number of groups (with slight modifications that may help to increase success)10,11. In addition, the determination of cAMP production allows for a direct read-out of the incretin responsiveness of the &#946;-cells. In conjunction with cAMP measurement, protein content and insulin secretion can also be quantified from the same cAMP sample prep, helping to determine whether a defect in &#946;-cell function lies proximal or distal to cAMP10. The final cAMP content and insulin secretion application in this protocol can be a very powerful tool for understanding the influence of pharmaceutical and dietary constituents, among others, on cAMP and insulin secretion. In addition to stimulation from glucose alone, other compounds can be used to measure changes in cAMP and insulin secretion10,11.
Finally, although insulin is the primary hormone we assay from isolated islets, other hormones, such as glucagon and somatostatin, as well as cytokines, eicosanoids, and cyclic adenosine monophosphate, can also be measured, either by a transient stimulation assay or by quantification of their levels in culture medium12. Finally, although outside of the scope of this manuscript, islet isolation with the described collagenase isolation method allows for islet preservation so that many other downstream applications may be pursued, such as islet transplantation, RNA isolation for quantitative real time PCR or microarray analyses, protein isolation for Western blotting, islet embedding and immunofluorescent imaging, and [3H]-thymidine incorporation as a measure of islet cell replication, some of which have been described in previous JoVE articles13-16. Overall, following the islet isolation procedure described in the protocol may provide a researcher with important and useful information for developing therapies and promoting drug discovery aimed at enhancing &#946;-cell function.

<table><tbody><tr><td>Collagenase from &lt;em&gt;Clostridium histolyticum&lt;/em&gt; suitable for isolating active islets</td><td>Sigma-Aldrich</td><td>C7657</td><td></td></tr><tr><td>Ficoll 400</td><td>Sigma-Aldrich</td><td>F9378</td><td></td></tr><tr><td>Hanks Balanced Salt Solution 10X</td><td>Invitrogen (Gibco)</td><td>14065-056</td><td></td></tr><tr><td>HEPES</td><td>Sigma-Aldrich</td><td>H3375</td><td></td></tr><tr><td>RPMI 1640 (powder)</td><td>Invitrogen (Gibco)</td><td>31800-022</td><td></td></tr><tr><td>Albumin from Bovine Serum (BSA)</td><td>Sigma-Aldrich</td><td>A7888</td><td></td></tr><tr><td>3/0 Silk Suture Thread</td><td>Fine Science Tools</td><td>18020-30</td><td></td></tr><tr><td>Dumont #5 Forceps</td><td>Fine Science Tools</td><td>11251-10</td><td></td></tr><tr><td>0.8 mm Forceps&amp;nbsp;&amp;nbsp;</td><td>Fine Science Tools</td><td>11050-10</td><td></td></tr><tr><td>Curved Scissors</td><td>Fine Science Tools</td><td>14061-10</td><td></td></tr><tr><td>Vannas-T&amp;uuml;bingen Spring Scissors - Straight/Sharp/8.5 cm/5 mm Cutting Edge</td><td>Fine Science Tools</td><td>15003-08</td><td></td></tr><tr><td>Dissecting Scissors</td><td>Fine Science Tools</td><td>14002-14</td><td></td></tr><tr><td>5 ml BD Luer-Lok Syringe</td><td>BD</td><td>309646</td><td></td></tr><tr><td>1 ml BD syringe</td><td>BD</td><td>309628</td><td></td></tr><tr><td>30 G BD Needle 1/2&quot; Length</td><td>BD</td><td>305106</td><td></td></tr><tr><td>27 G BD Needle 1/2&quot; Length</td><td>BD</td><td>305109</td><td></td></tr><tr><td>Sharpening Stone</td><td>Fine Science Tools</td><td>29008-01</td><td></td></tr><tr><td>2-2-2-tribromoethanol</td><td>Sigma-Aldrich</td><td>T48402-25G</td><td></td></tr><tr><td>2-methyl-2-butanol</td><td>Sigma-Aldrich</td><td>240486-100mL</td><td></td></tr><tr><td>Sodium Chloride (NaCl)</td><td>Sigma-Aldrich</td><td>S9888</td><td></td></tr><tr><td>Potassium Chloride</td><td>Sigma-Aldrich</td><td>P3911</td><td></td></tr><tr><td>Monopotassium Phosphate (KH&lt;sub&gt;2&lt;/sub&gt;PO&lt;sub&gt;4&lt;/sub&gt;)</td><td>Sigma-Aldrich</td><td>P0662</td><td></td></tr><tr><td>Sodium Bicarbonate (NaCHO&lt;sub&gt;3&lt;/sub&gt;)</td><td>Sigma-Aldrich</td><td>S6014</td><td></td></tr><tr><td>CaCl&lt;sub&gt;2&lt;/sub&gt;&amp;#183;2H&lt;sub&gt;2&lt;/sub&gt;O</td><td>Sigma-Aldrich</td><td>C3881</td><td></td></tr><tr><td>MgSO&lt;sub&gt;4&lt;/sub&gt;&amp;#183;7H&lt;sub&gt;2&lt;/sub&gt;O</td><td>Sigma-Aldrich</td><td>M9397</td><td></td></tr><tr><td>Penicillin-Streptomycin</td><td>Invitrogen (Gibco)</td><td>15140-122</td><td></td></tr><tr><td>Heat Inactivated Fetal Bovine Serum (H.I. FBS)</td><td>Fisher Scientific</td><td>SH30088.03HI</td><td></td></tr><tr><td>3-Isobutyl-1-methylxanthine (IBMX)</td><td>Sigma-Aldrich</td><td>5879-100MG</td><td></td></tr></tbody></table>

a method for mouse pancreatic islet isolation and intracellular camp determination

Uncontrolled glycemia is a hallmark of diabetes mellitus and promotes morbidities like neuropathy, nephropathy, and retinopathy. With the increasing prevalence of diabetes, both immune-mediated type 1 and obesity-linked type 2, studies aimed at delineating diabetes pathophysiology and therapeutic mechanisms are of critical importance. The &#946;-cells of the pancreatic islets of Langerhans are responsible for appropriately secreting insulin in response to elevated blood glucose concentrations. In addition to glucose and other nutrients, the &#946;-cells are also stimulated by specific hormones, termed incretins, which are secreted from the gut in response to a meal and act on &#946;-cell receptors that increase the production of intracellular cyclic adenosine monophosphate (cAMP). Decreased &#946;-cell function, mass, and incretin responsiveness are well-understood to contribute to the pathophysiology of type 2 diabetes, and are also being increasingly linked with type 1 diabetes. The present mouse islet isolation and cAMP determination protocol can be a tool to help delineate mechanisms promoting disease progression and therapeutic interventions, particularly those that are mediated by the incretin receptors or related receptors that act through modulation of intracellular cAMP production. While only cAMP measurements will be described, the described islet isolation protocol creates a clean preparation that also allows for many other downstream applications, including glucose stimulated insulin secretion, [3H]-thymidine incorporation, protein abundance, and mRNA expression.

To ensure a high islet yield during isolation, surgical techniques outlined in the protocol should be followed closely. Although the techniques presented here will be tailored to each laboratory, there are a few critical steps that will lead to a successful isolation. In order to make the common bile duct easily accessible, it is recommended that the organs be displaced to the right side of the mouse (Figure 1). Moreover, this will allow the pancreas to inflate with a smaller amount of resistance since t...

Watch this Scientific Journal Video about A Method for Mouse Pancreatic Islet Isolation and Intracellular cAMP Determination at JoVE.com

A Method for Mouse Pancreatic Islet Isolation and Intracellular cAMP Determination

Assaying in vitro &#946;-cell function using isolated mouse islets of Langerhans is an important component in the study of diabetes pathophysiology and therapeutics. While many&#160;downstream applications are available, this protocol specifically describes the measurement of intracellular cyclic adenosine monophosphate (cAMP) as an essential parameter determining &#946;-cell function.

Uncontrolled glycemia is a hallmark of diabetes mellitus and promotes morbidities like neuropathy, nephropathy, and retinopathy. With the increasing ...

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Research

JoVE Journal

Biology

65.1K Views.  University of Wisconsin-Madison. Assaying in vitro β-cell function using isolated mouse islets of Langerhans is an important component in the study of diabetes pathophysiology and therapeutics. While many downstream applications are available, this protocol specifically describes the measurement of intracellular cyclic adenosine monophosphate (cAMP) as an essential parameter determining β-cell function.

Video: A Method for Mouse Pancreatic Islet Isolation and Intracellular cAMP Determination

A Method for Murine Islet Isolation and Subcapsular Kidney Transplantation

Since the early pioneering work of Ballinger and Reckard demonstrating that transplantation of islets of Langerhans into diabetic rodents could normalize their blood glucose levels, islet transplantation has been proposed to be a potential treatment for type 1 diabetes 1,2. More recently, advances in human islet transplantation have further strengthened this view 1,3. However, two major limitations prevent islet transplantation from being a widespread clinical reality: (a) the requirement for large numbers of islets per patient, which severely reduces the number of potential recipients, and (b) the need for heavy immunosuppression, which significantly affects the pediatric population of patients due to their vulnerability to long-term immunosuppression. Strategies that can overcome these limitations have the potential to enhance the therapeutic utility of islet transplantation.
Islet transplantation under the mouse kidney capsule is a widely accepted model to investigate various strategies to improve islet transplantation. This experiment requires the isolation of high quality islets and implantation of islets to the diabetic recipients. Both procedures require surgical steps that can be better demonstrated by video than by text. Here, we document the detailed steps for these procedures by both video and written protocol. We also briefly discuss different transplantation models: syngeneic, allogeneic, syngeneic autoimmune, and allogeneic autoimmune.

Transplantation of isolated islets has been proposed to be a potential treatment for type 1 diabetes. Here we describe a method to isolate islets from mouse pancreata and transplant them to the subcapsular space of the kidney.

Since the early pioneering work of Ballinger and Reckard demonstrating that transplantation of islets of Langerhans into diabetic rodents could normalize ...

Medicine

Single-cell Transcriptomic Analyses of Mouse Pancreatic Endocrine Cells

Pancreatic endocrine cells, which are clustered in islets, regulate blood glucose stability and energy metabolism. The distinct cell types in islets, including insulin-secreting &#946; cells, are differentiated from common endocrine progenitors during the embryonic stage. Immature endocrine cells expand via cell proliferation and mature during a long postnatal developmental period. However, the mechanisms underlying these processes are not clearly defined. Single-cell RNA-sequencing is a promising approach for the characterization of distinct cell populations and tracing cell lineage differentiation pathways. Here, we describe a method for the single-cell RNA-sequencing of isolated pancreatic &#946; cells from embryonic, neonatal and postnatal pancreases.

We describe a method for the isolation of endocrine cells from embryonic, neonatal and postnatal pancreases followed by single-cell RNA sequencing. This method allows analyses of pancreatic endocrine lineage development, cell heterogeneity and transcriptomic dynamics.

Pancreatic endocrine cells, which are clustered in islets, regulate blood glucose stability and energy metabolism. The distinct cell types in islets, ...

Developmental Biology

Leprdb Mouse Model of Type 2 Diabetes: Pancreatic Islet Isolation and Live-cell 2-Photon Imaging Of Intact Islets

Type 2 diabetes is a chronic disease affecting 382 million people in 2013, and is expected to rise to 592 million by 2035 1. During the past 2 decades, the role of beta-cell dysfunction in type 2 diabetes has been clearly established 2. Research progress has required methods for the isolation of pancreatic islets. The protocol of the islet isolation presented here shares many common steps with protocols from other groups, with some modifications to improve the yield and quality of isolated islets from both the wild type and diabetic Leprdb (db/db) mice. A live-cell 2-photon imaging method is then presented that can be used to investigate the control of insulin secretion within islets.

Leprdb Mouse Model of Type 2 Diabetes: Pancreatic Islet Isolation and Live-cell 2-Photon Imaging Of Intact Islets

We present here a protocol for the isolation of islets from the mouse model of type 2 diabetes, Leprdb and details of a live-cell assay for measurement of insulin secretion from intact islets that utilizes 2 photon microscopy.

Type 2 diabetes is a chronic disease affecting 382 million people in 2013, and is expected to rise to 592 million by 2035 1. During the past 2 decades, ...

A Murine Pancreatic Islet Cell-based Screening for Diabetogenic Environmental Chemicals

Exposure to certain environmental chemicals in human and animals has been found to cause cellular damage of the pancreatic &#946; cells which will lead to the development of type 2 diabetes mellitus (T2DM). Although the mechanisms for the chemical-induced &#946; cell damage were unclear and likely to be complex, one recurring finding is that these chemicals induce oxidative stress leading to the generation of excessive reactive oxygen species (ROS) which induce damage to the &#946; cell. To identify potential diabetogenic environmental chemicals, we isolated pancreatic islet cells from C57BL/6 mice and cultured islet cells in 96-well cell culture plates; then, the islet cells were dosed with chemicals and the ROS generation was detected by 2',7'-dichlorofluorescein (DCFH-DA) fluorescent dye. Using this method, we found that bisphenol A (BPA), Benzo[a]pyrene (BaP), and polychlorinated biphenyls (PCBs), could induce high levels of ROS, suggesting that they may potentially induce damage in islet cells. This method should be useful for screening diabetogenic xenobiotics. In addition, the cultured islet cells may also be adapted for in vitro analysis of chemical-induced toxicity in pancreatic cells.

Here we present a protocol to isolate mouse pancreatic islet cells for screening the ROS inductions by the xenobiotics in order to identify the potential diabetogenic xenobiotic chemicals.

Exposure to certain environmental chemicals in human and animals has been found to cause cellular damage of the pancreatic &#946; cells which will lead to ...

Immunology and Infection

Mouse Islet of Langerhans Isolation using a Combination of Purified Collagenase and Neutral Protease

The interrogation of beta cell gene expression and function in vitro has squarely shifted over the years from the study of rodent tumorigenic cell lines to the study of isolated rodent islets. Primary islets offer the distinct advantage that they more faithfully reflect the biology of intracellular signaling pathways and secretory responses. Whereas the method of islet isolation using tissue dissociating enzyme (TDE) preparations has been well established in many laboratories1-4, variations in the consistency of islet yield and quality from any given rodent strain limit the extent and feasibility of primary islet studies. These variations often occur as a result of the crude partially purified TDEs used in the islet isolation procedure; TDEs frequently exhibit lot-to-lot variations in activity and often require adjustments to the dose of enzyme used. A small number of reports have used purified TDEs for rodent cell isolations5, 6, but the practice is not widespread despite the routine use and advantages of purified TDEs for human islet isolations. In collaboration with VitaCyte, LLC (Indianapolis, IN), we developed a modified mouse islet isolation protocol based on that described by Gotoh7, 8, in which the TDEs are perfused directly into the pancreatic duct of mice, followed by crude tissue fractionation through a Histopaque gradient9, and isolation of purified islets. A significant difference in our protocol is the use of purified collagenase (CIzyme MA) and neutral protease (CIzyme BP) combination. The collagenase was characterized by the use of a6 fluorescence collagen degrading activity (CDA) assay that utilized fluorescently labeled soluble calf skin fibrils as substrate6. This substrate is more predictive of the kinetics of collagen degradation in the tissue matrix because it relies on native collagen as the substrate. The protease was characterized with a sensitive fluorescent kinetic assay10. Utilizing these improved assays along with more traditional biochemical analysis enable the TDE to be manufactured more consistently, leading to improved performance consistency between lots. The protocol described in here was optimized for maximal islet yield and optimal islet morphology using C57BL/6 mice. During the development of this protocol, several combinations of collagenase and neutral proteases were evaluated at different concentrations, and the final ratio of collagenase:neutral protease of 35:10 represents enzyme performance comparable to Sigma Type XI. Because significant variability in average islet yields from different strains of rats and mice have been reported, additional modifications of the TDE composition should be made to improve the yield and quality of islets recovered from different species and strains.

A detailed description of mouse islet isolation is described using the technique of in situ pancreatic ductal cannulation and perfusion of a combination of purified collagenase and neutral protease.

The interrogation of beta cell gene expression and function in vitro has squarely shifted over the years from the study of rodent tumorigenic cell lines ...

Visualization of Endogenous Mitophagy Complexes In Situ in Human Pancreatic Beta Cells Utilizing Proximity Ligation Assay

Mitophagy is an essential mitochondrial quality control pathway, which is crucial for pancreatic islet beta cell bioenergetics to fuel glucose-stimulated insulin release. Assessment of mitophagy is challenging and often requires genetic reporters or multiple complementary techniques not easily utilized in tissue samples, such as primary human pancreatic islets. Here we demonstrate a robust approach to visualize and quantify formation of key endogenous mitophagy complexes in primary human pancreatic islets. Utilizing the sensitive proximity ligation assay technique to detect interaction of the mitophagy regulators NRDP1 and USP8, we are able to specifically quantify formation of essential mitophagy complexes in situ. By coupling this approach to counterstaining for the transcription factor PDX1, we can quantify mitophagy complexes, and the factors that can impair mitophagy, specifically within beta cells. The methodology we describe overcomes the need for large quantities of cellular extracts required for other protein-protein interaction studies, such as immunoprecipitation (IP) or mass spectrometry, and is ideal for precious human islet&#160;samples generally not available in sufficient quantities for these approaches. Further, this methodology obviates the need for flow sorting techniques to purify beta cells from a heterogeneous islet population for downstream protein applications. Thus, we describe a valuable protocol for visualization of mitophagy highly compatible for use in heterogeneous and limited cell populations.

This protocol outlines a method for quantitative analysis of mitophagy protein complex formation specifically in beta cells from primary human islet samples. This technique thus allows analysis of mitophagy from limited biological material, which are crucial in precious human pancreatic beta cell samples.

Mitophagy is an essential mitochondrial quality control pathway, which is crucial for pancreatic islet beta cell bioenergetics to fuel glucose-stimulated ...

A Simple High Efficiency Protocol for Pancreatic Islet Isolation from Mice

Pancreatic islets, also called the Islets of Langerhans, are a cluster of endocrine cells which produces hormones for glucose regulation and other important biological functions. The islets primarily consist of five types of hormone-secreting cells: &#945; cells secrete glucagon, &#946; cells secrete insulin, &#948; cells secrete somatostatin, &#949; cells secrete ghrelin, and PP cells secrete pancreatic polypeptide. Sixty to 80% of the cells in the islets are &#946; cells, which are the most important cell population to study insulin secretion. Pancreatic islets are a crucial model system to study ex vivo insulin secretion. Acquiring high quality islets is of great importance for diabetes research. Most islet isolation procedures require technically difficult to access site of collagenase injection, harsh and complex digestion procedures, and multiple density gradient purification steps. This paper features a simple high yield mouse islet isolation method with detailed descriptions and realistic demonstrations, showing the following specific steps: 1) injection of collagenase P at the ampulla of Vater, a small area joining the pancreatic duct and the common bile duct, 2) enzymatic digestion and mechanical separation of the exocrine pancreas, and 3) a single gradient purification step. The advantages of this method are the injection of digestive enzyme using the more accessible ampulla of Vater, more complete digestion using combination of enzymatic and mechanical approaches, and a simpler single gradient purification step. This protocol produces approximately 250&#8212;350 islets per mouse; and islets are suitable for various ex vivo studies. Possible caveats of this procedure are potentially damaged islets due to enzymatic digestion and/or prolonged gradient incubation, all of which can be largely avoided by careful ad justification of incubation time.

This islet isolation protocol described a novel route of collagenase injection to digest the exocrine tissue and a simplified gradient procedure to purify the islets from mice. It involves enzymatic digestion, gradient separation/purification, and islet hand-picking. Successful isolation can yield 250&#8211;350 high quality and fully functional islets per mouse.

Pancreatic islets, also called the Islets of Langerhans, are a cluster of endocrine cells which produces hormones for glucose regulation and other ...

Imaging Calcium Dynamics in Subpopulations of Mouse Pancreatic Islet Cells

Pancreatic islet hormones regulate blood glucose homeostasis. Changes in blood glucose induce oscillations of cytosolic calcium in pancreatic islet cells that trigger secretion of three main hormones: insulin (from &#946;-cells), glucagon (&#945;-cells) and somatostatin (&#948;-cells). &#946;-Cells, which make up the majority of islet cells and are electrically coupled to each other, respond to the glucose stimulus as one single entity. The excitability of the minor subpopulations, &#945;-cells and &#948;-cells (making up around 20% (30%) and 4% (10%) of the total rodent1 (human2) islet cell numbers, respectively) is less predictable and is therefore of special interest.
Calcium sensors are delivered into the peripheral layer of cells within the isolated islet. The islet or a group of islets is then immobilized and imaged using a fluorescence microscope. The choice of the imaging mode is between higher throughput (wide-field) and better spatial resolution (confocal). Conventionally, laser scanning confocal microscopy is used for imaging tissue, as it provides the best separation of the signal between the neighboring cells. A wide-field system can be utilized too, if the contaminating signal from the dominating population of &#946;-cells is minimized.
Once calcium dynamics in response to specific stimuli have been recorded, data are expressed in numerical form as fluorescence intensity vs. time, normalized to the initial fluorescence and baseline-corrected, to remove the effects linked to bleaching of the fluorophore. Changes in the spike frequency or partial area under the curve (pAUC) are computed vs. time, to quantify the observed effects. pAUC is more sensitive and quite robust whereas spiking frequency provides more information on the mechanism of calcium increase.
Minor cell subpopulations can be identified using functional responses to marker compounds, such as adrenaline and ghrelin, that induce changes in cytosolic calcium in a specific populations of islet cells.

Here, we present a protocol for imaging and quantifying calcium dynamics in heterogeneous cell populations, such as pancreatic islet cells. Fluorescent reporters are delivered into the peripheral layer of cells within the islet, which is then immobilized and imaged, and per-cell analysis of the dynamics of fluorescence intensity is performed.

Pancreatic islet hormones regulate blood glucose homeostasis. Changes in blood glucose induce oscillations of cytosolic calcium in pancreatic islet cells ...

Streamlining Mouse Pancreatic Endothelial Cell Extraction for Disease Studies

Isolation of Mouse Pancreatic Endothelial Cells

The pancreas is a vital organ for maintaining metabolic balance within the body, in part due to its production of metabolic hormones such as insulin and glucagon, as well as digestive enzymes. The pancreas is also a highly vascularized organ, a feature facilitated by the intricate network of pancreatic capillaries. This extensive capillary network is made up of highly fenestrated endothelial cells (ECs) important for pancreas development and function. Accordingly, the dysfunction of ECs can contribute to that of the pancreas in diseases like diabetes and cancer. Thus, researching the function of pancreatic ECs (pECs) is important not only for understanding pancreas biology but also for developing its pathologies. Mouse models are valuable tools to study metabolic and cardiovascular diseases. However, there has not been an established protocol with sufficient details described for the isolation of mouse pECs due to the relatively small population of ECs and the abundant digestive enzymes potentially released from the acinar tissue that can lead to cell damage and, thus, low yield. To address these challenges, we devised a protocol to enrich and recover mouse pECs, combining gentle physical and chemical dissociation and antibody-mediated selection. The protocol presented here provides a robust method to extract intact and viable ECs from the whole mouse pancreas. This protocol is suitable for multiple downstream assays and may be applied to various mouse models.

This protocol describes the isolation of mouse endothelial cells from whole pancreas.

The pancreas is a vital organ for maintaining metabolic balance within the body, in part due to its production of metabolic hormones such as insulin and ...

Pancreatic Islets Isolation through Collagenase Perfusion: An Enzymatic Method to Isolate Pancreatic Islet Cells

Source: Villarreal D. et al.&#160;<a href="https://jove.unicartagenaproxy.elogim.com/v/57048/" target="_blank">A Simple High Efficiency Protocol for Pancreatic Islet Isolation from Mice</a>. J. Vis. Exp. (2019)
Pancreatic islets, also called the Islets of Langerhans, are a cluster of endocrine cells which produces hormones for glucose regulation and other important biological functions.&#160;This protocol explains a method for isolating pancreatic islets by first perfusing collagenase via Ampulla of Vater to digest the exocrine pancreatic tissue and a simplified density gradient centrifugation to purify the islets from mice.

Izolacja wysp trzustkowych poprzez perfuzję kolagenazy: enzymatyczna metoda izolowania komórek wysp trzustkowych

Source: Villarreal D. et al.&#160;A Simple High Efficiency Protocol for Pancreatic Islet Isolation from Mice. J. Vis. Exp. (2019)
Pancreatic islets, also ...