1. Making a custom-made stand for cell culture inserts
The base of a 5 ml pipette tip (ISC BioExpress, #P-3250-19) has an inner diameter of 13 mm, which perfectly matches the bottom size (12.6 mm, outer diameter) of a 10 mm (inner diameter) NUNC cell culture insert (8 μm, Polycarbonate membrane, Thermal, #137443). To make the stand, the pipette was cut off near the base to produce a 6 mm long hollow cylinder. Then, pieces were removed from the side of the cylinder using a flame-heated blade to create 3 legs (4 mm in height) under a ring (2 mm in height), which raised the height of the inserts by approximately 5 mm.
2. Preparation of sterile filter paper for attachment and culture of porcine retina
Whatman 4M Filter paper (Cat No. 1004) was cut into a circular shape (6.3 mm in diameter) with a small, triangular handle that was used for moving the filter paper into a glass tube for sterilization or once the retina was attached (as shown in the video).
3. Preparation of retinal explants
Eyes from 5- to 9-month old, 150-230 lbs, American Yorkshire pigs were obtained from a local abattoir within three hours of enucleation (transported on ice). Upon arrival, eyes were cleaned of extraneous tissue, dipped in betadine solution (10% Povidone-iodine, The Purdue Frederique Company, Stamford, CT) and washed twice in Dulbecco’s Modified Eagle Medium (DMEM with 1g/L glucose, L-glutamine, and sodium pyruvate, Cellgro-mediatech Inc., Manasses, VA) supplemented with 2.5 μg/ml Amphotericin B (Gibco-Invitrogen, Carlsbad, CA). The anterior segment was removed, exposing the neural retina. Six-mm trephine blades (Storz Ophthalmic-Bausch and Lomb, Manchester, MO) were used to cut equatorial, full-thickness posterior segment explants. The retina was subsequently peeled off by gently applying a piece of dry sterile filter paper onto the ganglion cell layer, lifting off the neural retina, and placing the filter paper with attached retina onto the culture insert, photoreceptors facing up. The insert was then placed into culture medium, making sure to fully cover the retina, in a 12-well culture dish (Fisher). Multiple explants were obtained routinely and cultured from a single eye.
4. Tissue culture
The retinal tissue was cultured in Eagle’s Minimum Essential Medium (MEM, Invitrogen-Gibco-Life Technologies Inc., Rockville, MD), pH 7.4, supplemented with 0.2 mg/ml glutamine, 10 μg/ml porcine insulin, 1 mM pyruvate, 0.1 mM L-ascorbic acid, 100 U/ml penicillin, 100 μg/ml streptomycin, and 250 ng/ml amphotericin B (Antibiotic Antimycotic: Sigma, St. Louis, MO), and aerated with humidified 5% CO2, balance air, at 37 °C. Medium was exchanged every two days.
Tissue can be used, treated with a variety of reagents or probes, or left untreated for subsequent biochemical or morphological analyses. The section below describes procedures to create consistent full-thickness retinal cross-sections.
5. Sectioning
6. Immunohistochemistry
Use any standard protocol. Immunolabeled thick sections can be viewed with a confocal microscope.
7. Representative Results:
Morphology was preserved during the seven-day period of culture. Images of retina before and after culturing are available in the video.
Name of the reagent | Company | Catalogue number | Comments |
MEM | Invitrogen-Gibco | 10370-021 | |
5 mL pipette tip | ISC BioExpress | P-3250-19 | |
NUNC cell culture insert | Thermal | 137443 | 8μm, Polycarbonate |
Whatman 4M Filter paper | Whatman | 1004 | |
DMEM | Cellgro-mediatech Inc | 10-013-CV | |
Agar | Fluka | 05040 | |
Fungizone Amphotericin B | Invitrogen-Gibco | 15290018 | |
Trephine blades | Bausch and Lomb | T3096 | 6.00mm |
O.C.T. Compound | Electron Microscopy Sciences | 62550-01 | 4583 |
Sciences | |||
Cryostat | Leica | CM1900 | |
Vibratome | Leica | Series 1000 | |
Confocal microscopy; | Carl Zeiss | LSM510 | |
Anti-Synaptic Vesicle Protein 2 (SV2) mouse monoclonal antibody | DSHB | N/A | |
Anti-Glial Fibrillary Acidic Protein (GFAP) polyclonal rabbit antibody | DAKO | DAKO | |
Propidium Iodide (PI) | Sigma | P4170 |
There is a recognized demand for in vitro models that can replace or reduce animal experiments. Porcine retina has a similar neuronal structure to human retina and is therefore a valuable species for studying mechanisms of human retinal injury and degenerative disease. Here we describe a cost-effective technique for organotypic culture of adult porcine retina isolated from eyes obtained from an abattoir. After removing the anterior segment, a trephine blade was used to create multiple neural retina-Bruch’s membrane-RPE-choroid-sclera explants from the posterior segment of adult porcine eyes. A piece of sterile filter paper was used to lift the neural retina off from each explant. The filter paper-retina complex was cultured (photoreceptor side up) atop an insert, which was held away from the bottom of the culture dish by a custom-made stand. The stand allows for good circulation of the culture medium to both sides of the retina. Overall, this procedure is simple, reproducible, and permits preservation of native retinal structure for at least seven days, making it a useful model for a variety of morphological, pharmacological, and biochemical studies on mammalian retina.
There is a recognized demand for in vitro models that can replace or reduce animal experiments. Porcine retina has a similar neuronal structure to human retina and is therefore a valuable species for studying mechanisms of human retinal injury and degenerative disease. Here we describe a cost-effective technique for organotypic culture of adult porcine retina isolated from eyes obtained from an abattoir. After removing the anterior segment, a trephine blade was used to create multiple neural retina-Bruch’s membrane-RPE-choroid-sclera explants from the posterior segment of adult porcine eyes. A piece of sterile filter paper was used to lift the neural retina off from each explant. The filter paper-retina complex was cultured (photoreceptor side up) atop an insert, which was held away from the bottom of the culture dish by a custom-made stand. The stand allows for good circulation of the culture medium to both sides of the retina. Overall, this procedure is simple, reproducible, and permits preservation of native retinal structure for at least seven days, making it a useful model for a variety of morphological, pharmacological, and biochemical studies on mammalian retina.
There is a recognized demand for in vitro models that can replace or reduce animal experiments. Porcine retina has a similar neuronal structure to human retina and is therefore a valuable species for studying mechanisms of human retinal injury and degenerative disease. Here we describe a cost-effective technique for organotypic culture of adult porcine retina isolated from eyes obtained from an abattoir. After removing the anterior segment, a trephine blade was used to create multiple neural retina-Bruch’s membrane-RPE-choroid-sclera explants from the posterior segment of adult porcine eyes. A piece of sterile filter paper was used to lift the neural retina off from each explant. The filter paper-retina complex was cultured (photoreceptor side up) atop an insert, which was held away from the bottom of the culture dish by a custom-made stand. The stand allows for good circulation of the culture medium to both sides of the retina. Overall, this procedure is simple, reproducible, and permits preservation of native retinal structure for at least seven days, making it a useful model for a variety of morphological, pharmacological, and biochemical studies on mammalian retina.