Observing Islet Function and Islet-Immune Cell Interactions in Live Pancreatic Tissue Slices
Summary
This study presents the application of live pancreatic tissue slices to the study of islet physiology and islet-immune cell interactions.
Abstract
Live pancreatic tissue slices allow for the study of islet physiology and function in the context of an intact islet microenvironment. Slices are prepared from live human and mouse pancreatic tissue embedded in agarose and cut using a vibratome. This method allows for the tissue to maintain viability and function in addition to preserving underlying pathologies such as type 1 (T1D) and type 2 diabetes (T2D). The slice method enables new directions in the study of the pancreas through the maintenance of the complex structures and various intercellular interactions that comprise the endocrine and exocrine tissues of the pancreas. This protocol demonstrates how to perform staining and time-lapse microscopy of live endogenous immune cells within pancreatic slices along with assessments of islet physiology. Further, this approach can be refined to discern immune cell populations specific for islet cell antigens using major histocompatibility complex-multimer reagents.
Introduction
Involvement of the pancreas is pathognomonic to diseases such as pancreatitis, T1D, and T2D1,2,3. The study of function in isolated islets usually involves removal of the islets from their surrounding environment4. The live pancreatic tissue slice method was developed to allow for the study of pancreatic tissue while maintaining intact islet microenvironments and avoiding the use of stressful islet isolation procedures5,6,7. Pancreatic tissue slices from human donor tissue have been successfully used to study T1D and have demonstrated processes of beta cell loss and dysfunction in addition to immune cell infiltration8,9,10,11,12,13. The live pancreatic tissue slice method can be applied to both mouse and human pancreatic tissue5,6,8. Human pancreatic tissue slices from organ donor tissues are obtained through a collaboration with the Network for Pancreatic Organ Donors with Diabetes (nPOD). Mouse slices can be generated from a variety of different mouse strains.
This protocol will focus on non-obese diabetic-recombination activating gene-1-null (NOD.Rag1-/-) and T cell receptor transgenic (AI4) (NOD.Rag1-/-.AI4α/β) mouse strains. NOD.Rag1-/- mice are unable to develop T and B cells due to a disruption in the recombination-activating gene 1 (Rag1)14. NOD.Rag1-/-.AI4α/β mice are used as a model for accelerated type 1 diabetes because they produce a single T cell clone that targets an epitope of insulin, resulting in consistent islet infiltration and rapid disease development15. The protocol featured here describes procedures for functional and immunological studies using live human and mouse pancreatic slices through the application of confocal microscopy approaches. The techniques described herein include viability assessments, islet identification and location, cytosolic Ca2+ recordings, as well as staining and identification of immune cell populations.
Protocol
Representative Results
Discussion
The objective of this protocol is to explicate the generation of pancreas slices and the procedures needed to employ the slices in functional and immunological studies. There are many benefits to using live pancreatic slices. However, there are several critical steps that are essential for the tissue to remain viable and useful during the described experiment protocols. It is imperative to work quickly. The length of time between injecting the pancreas and generating the slices on the vibratome should be minimized to mai…
Disclosures
The authors have nothing to disclose.
Acknowledgements
This work was funded by NIH grants R01 DK123292, T32 DK108736, UC4 DK104194, UG3 DK122638, and P01 AI042288. This research was performed with the support of the Network for Pancreatic Organ donors with Diabetes (nPOD; RRID:SCR_014641), a collaborative type 1 diabetes research project sponsored by JDRF (nPOD: 5-SRA-2018-557-Q-R), and The Leona M. & Harry B. Helmsley Charitable Trust (Grant #2018PG-T1D053). The content and views expressed are the responsibility of the authors and do not necessarily reflect the official view of nPOD. Organ Procurement Organizations (OPO) partnering with nPOD to provide research resources are listed at http://www.jdrfnpod.org/for-partners/npod-partners/. Thank you to Dr. Kevin Otto, University of Florida, for providing the vibratome used to generate mouse slices.
Materials
| #3 Style Scalpel Handle | Fisherbrand | 12-000-163 | |
| 1 M HEPES | Fisher Scientific | BP299-100 | HEPES Buffer, 1M Solution |
| 10 cm Untreated Culture Dish | Corning | 430591 | |
| 10 mL Luer-Lok Syringe | BD | 301029 | BD Syringe with Luer-Lok Tips |
| 27 G Needle | BD | BD 305109 | BD General Use and PrecisionGlide Hypodermic Needles |
| 35 mm coverglass-bottom Petri dish | Ibidi | 81156 | µ-Dish 35 mm, high |
| 50 mL syringe | BD | 309653 | |
| 8-well chambered coverglass | Ibidi | 80826 | µ-Slide 8 Well |
| APC anti-mouse CD8a antibody | Biolegend | 100712 | |
| BSA | Fisher Scientific | 199898 | |
| Calcium chloride | Sigma | C5670 | CaCl2 |
| Calcium chloride dihydrate | Sigma | C7902 | CaCl2 (dihydrate) |
| Compact Digital Rocker | Thermo Fisher Scientific | 88880020 | |
| Confocal laser-scanning microscope | Leica | SP8 | Pinhole = 1.5-2 airy units; acquired with 10x/0.40 numerical aperture HC PL APO CS2 dry and 20x/0.75 numerical aperture HC PL APO CS2 dry objectives at 512 × 512 pixel resolution |
| D-(+)-Glucose | Sigma | G7021 | C6H12O6 |
| ddiH2O | |||
| Dithizone | Sigma-Aldrich | D5130-10G | |
| DMSO | Invitrogen | D12345 | Dimethyl sulfoxide |
| Ethanol | Decon Laboratories | 2805 | |
| Falcon 35 mm tissue culture dish | Corning | 353001 | Falcon Easy-Grip Tissue Culture Dishes |
| FBS | Gibco | 10082147 | |
| Feather No. 10 Surgical Blade | Electron Microscopy Sciences | 7204410 | |
| fluo-4-AM | Invitrogen | F14201 | cell-permeable Ca2+ indicator |
| Gel Control Super Glue | Loctite | 45198 | |
| Graefe Forceps | Fine Science Tools | 11049-10 | |
| Hardened Fine Scissors | Fine Science Tools | 14090-09 | |
| HBSS | Gibco | 14025092 | Hanks Balanced Salt Solution |
| HEPES | Sigma | H4034 | C8H18N2O4S |
| Ice bucket | Fisherbrand | 03-395-150 | |
| Isoflurane | Patterson Veterinary | NDC 14043-704-05 | |
| Johns Hopkins Bulldog Clamp | Roboz Surgical Store | RS-7440 | Straight; 500-900 Grams Pressure; 1.5" Length |
| Kimwipes | Kimberly-Clark Professional | 34705 | Kimtech Science™ Kimwipes™ Delicate Task Wipers, 2-Ply |
| LIVE/DEAD Viability/Cytotoxicity Kit | Invitrogen | L3224 | This kit contains the calcein-AM live cell dye. |
| Low glucose DMEM | Corning | 10-014-CV | |
| Magnesium chloride hexahydrate | Sigma | M9272 | MgCl2 (hexahydrate) |
| Magnesium sulfate heptahydrate | Sigma | M2773 | MgSO4 (heptahydrate) |
| Magnetic Heated Platform | Warner Instruments | PM-1 | Platform for imaging chamber for dynamic stimulation recordings |
| Microwave | GE | JES1460DSWW | |
| Nalgene Syringe Filter | Thermo Fisher Scientific | 726-2520 | |
| No.4 Paintbrush | Michaels | 10269140 | |
| Open Diamond Bath Imaging Chamber | Warner Instruments | RC-26 | Imaging chamber for dynamic stimulation recordings |
| Oregon Green 488 BAPTA-1-AM | Invitrogen | O6807 | cell-permeable Ca2+ indicator |
| Overnight imaging chamber | Okolab | H201-LG | |
| PBS | Thermo Fisher Scientific | 20012050 | To make agarose for slice generation |
| PE-labeled insulin tetramer | Emory Tetramer Research Core | sequence YAIENYLEL | |
| Penicillin Streptomycin | Gibco | 15140122 | |
| Potassium chloride | Sigma | P5405 | KCl |
| Potassium phosphate monobasic | Sigma | P5655 | KH2PO4 |
| Razor Blades | Electron Microscopy Sciences | 71998 | For Vibratome; Double Edge Stainless Steel, uncoated |
| RPMI 1640 | Gibco | 11875093 | |
| SeaPlaque low melting-point agarose | Lonza | 50101 | To make agarose for slice generation |
| Slice anchor | Warner Instruments | 64-1421 | |
| Slice anchor (dynamic imaging) | Warner Instruments | 640253 | Slice anchor for dynamic imaging chamber |
| Sodium bicarbonate | Sigma | S5761 | NaHCO3 |
| Sodium chloride | Sigma | S5886 | NaCl |
| Sodium phosphate monohydrate | Sigma | S9638 | NaH2PO4 (monohydrate) |
| Soybean Trypsin Inhibitor | Sigma | T6522-1G | Trypsin inhibitor from Glycine max (soybean) |
| Stage Adapter | Warner Instruments | SA-20MW-AL | To fit imaging chamber for dynamic stimulation recordings on the microscope stage |
| Stage-top incubator | Okolab | H201 | |
| Stereoscope | Leica | IC90 E MSV266 | |
| SYTOX Blue Dead Cell Stain | Invitrogen | S34857 | blue-fluorescent nucleic acid stain |
| Transfer Pipet | Falcon | 357575 | Falcon™ Plastic Disposable Transfer Pipets |
| Valve Control System | Warner Instruments | VCS-8 | System for dynamic stimulation recordings |
| Vibratome VT1000 S | Leica | VT1000 S | |
| Water bath | Fisher Scientific | FSGPD02 | Fisherbrand Isotemp General Purpose Deluxe Water Bath GPD 02 |
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