Mouse models can be useful tools for investigating the biology of the retinal pigmented epithelium (RPE). It has been established that mice can develop an array of RPE pathologies. Here, we describe a phenotyping protocol to elucidate and quantify RPE pathologies in mice using light, transmission electron, and confocal microscopy.
Age-related macular degeneration (AMD) is a debilitating retinal disorder in aging populations. It is widely believed that dysfunction of the retinal pigmented epithelium (RPE) is a key pathobiological event in AMD. To understand the mechanisms that lead to RPE dysfunction, mouse models can be utilized by researchers. It has been established by previous studies that mice can develop RPE pathologies, some of which are observed in the eyes of individuals diagnosed with AMD. Here, we describe a phenotyping protocol to assess RPE pathologies in mice. This protocol includes the preparation and evaluation of retinal cross-sections using light microscopy and transmission electron microscopy, as well as that of RPE flat mounts by confocal microscopy. We detail the common types of murine RPE pathologies observed by these techniques and ways to quantify them through unbiased methods for statistical testing. As proof of concept, we use this RPE phenotyping protocol to quantify the RPE pathologies observed in mice overexpressing transmembrane protein 135 (Tmem135) and aged wild-type C57BL/6J mice. The main goal of this protocol is to present standard RPE phenotyping methods with unbiased quantitative assessments for scientists using mouse models of AMD.
Age-related macular degeneration (AMD) is a common blinding disease that affects populations over the age of 551. Many researchers believe that dysfunction within the retinal pigmented epithelium (RPE) is an early and crucial pathobiological event in AMD2. The RPE is a monolayer of polarized cells tasked with maintaining the homeostasis of neighboring photoreceptors and choroidal blood vessels3. A variety of models exist to investigate disease-associated mechanisms within the RPE, including cell culture models4,5 and mice6,7,8. A recent report has described standardized protocols and quality control criteria for RPE cell culture models4, yet no report has attempted to standardize the phenotyping of the RPE in mouse models. In fact, many publications on mouse models of AMD lack a complete description of the RPE or quantification of the RPE pathologies in them. The overall goal of this protocol is to present standard RPE phenotyping methods with unbiased quantitative assessments for scientists using AMD mouse models.
Previous publications have noted the presence of several RPE pathologies in mice through three imaging techniques. For instance, light microscopy allows researchers to view the gross morphology of the murine retina (Figure 1A) and detect RPE pathologies such as RPE thinning, vacuolization, and migration. RPE thinning in an AMD mouse model is exemplified by a deviation in the RPE height from their respective controls (Figure 1B). RPE vacuolization can be divided into two separate categories: microvacuolization (Figure 1C) and macrovacuolization (Figure 1D). RPE microvacuolization is summarized by the presence of vacuoles in the RPE that do not affect its overall height, whereas macrovacuolization is indicated by the presence of vacuoles that protrude into the outer segments of the photoreceptors. RPE migration is distinguished by the focal aggregate of pigment above the RPE monolayer in a retinal cross-section (Figure 1E). It should be noted that migratory RPE cells in AMD donor eyes exhibit immunoreactivity to immune cell markers, such as cluster of differentiation 68 (CD68)9, and could represent immune cells engulfing RPE debris or RPE undergoing transdifferentiation9. Another imaging technique called transmission electron microscopy can permit researchers to visualize the ultrastructure of the RPE and its basement membrane (Figure 2A). This technique can identify the predominant sub-RPE deposit in mice, known as the basal laminar deposit (BLamD) (Figure 2B)10. Lastly, confocal microscopy can reveal the structure of RPE cells through imaging RPE flat mounts (Figure 3A). This method can uncover RPE dysmorphia, the deviation of the RPE from its classic honeycomb shape (Figure 3B). It can also detect RPE multinucleation, the presence of three or more nuclei within an RPE cell (Figure 3C). For a summary of the types of RPE pathologies present in current AMD mouse models, we refer researchers to these reviews from the literature6,7.
Researchers studying AMD should be aware of the advantages and disadvantages of using mice to investigate RPE pathologies prior to the phenotyping protocol. Mice are advantageous because of their relatively short life span and cost-effectiveness, as well as their genetic and pharmacologic manipulability. Mice also exhibit RPE degenerative changes, including RPE migration, dysmorphia, and multinucleation, that are observed in AMD donor eyes11,12,13,14,15,16,17; this suggests that similar mechanisms may underly the development of these RPE pathologies in mice and humans. However, there are key differences that limit the translatability of mouse studies to human AMD. First, mice do not have a macula, an anatomically distinct region of the human retina necessary for visual acuity that is preferentially affected in AMD. Second, some RPE pathologies in mice, like RPE thinning and vacuolization, are not typically seen in AMD donor eyes18. Third, mice do not develop drusen, a hallmark of AMD pathology19. Drusen are lipid- and protein-containing deposits with very few basement membrane proteins that form between the RPE basal lamina and the inner collagenous layer of Bruch's membrane (BrM)19. Drusen differ from BLamD, the common sub-RPE deposit in mice, in both their composition and anatomical location. BLamDs are age- and stress-dependent extracellular matrix-enriched abnormalities that form between the RPE basal lamina of BrM and the basal infoldings of the RPE20. Interestingly, BLamDs have a similar protein composition and appearance in both mice and humans6,10,21. Recent work suggests BLamDs may act in the pathobiology of AMD by influencing the progression of AMD to its later stages18,22; thus, these deposits may represent diseased RPE in the mouse retina. Knowledge of these benefits and limitations is critical for researchers interested in translating results from mouse studies to AMD.
In this protocol, we discuss the methods to prepare eyes for light, transmission electron, and confocal microscopy to visualize RPE pathologies. We also describe how to quantify RPE pathologies in an unbiased manner for statistical testing. As proof of concept, we utilize the RPE phenotyping protocol to investigate the structural RPE pathologies observed in transmembrane protein 135- (Tmem135) overexpressing mice and aged wild-type (WT) C57BL/6J mice. In summary, we aim to describe the phenotyping methodology to characterize the RPE in AMD mouse models, since there are currently no standard protocols available. Researchers interested in examining and quantifying pathologies of the photoreceptors or choroid, which are also affected in AMD mouse models, may not find this protocol useful for their studies.
All procedures involving animal subjects have been approved by the Institutional Animal Care and Use Committee at the University of Wisconsin-Madison, and are in adherence with the Association for Research in Vision and Ophthalmology (ARVO) Statement for the Use of Animals in Ophthalmic and Vision Research.
1. Evaluation of mouse RPE by light microscopy
2. Evaluation of mouse RPE by transmission electron microscopy
3. Evaluation of mouse RPE through confocal microscopy
Completion of the RPE phenotyping protocol described in this article provides a quantitative analysis of the structural RPE abnormalities commonly observed in mouse models of AMD. To confirm the effectiveness of this protocol, we used it in mice that are known to display RPE pathologies, including transgenic mice that overexpress WT Tmem135 driven by the chicken beta-actin promoter (Tmem135 TG)30 and aged C57BL/6J mice31,32. The objective of these experiments is to show representative results that could be obtained using the methods described in this protocol to researchers new to mouse models.
We adhered to the methods in Step 1 of the protocol to process and evaluate eyes from WT and Tmem135 TG mice to evaluate RPE pathologies using light microscopy. We found that 4-month-old Tmem135 TG mice have a significant reduction in RPE thickness at two measured intervals relative to age-matched WT through an ANOVA with post-hoc Tukey test (Figure 4). These results indicate that the RPE is thinner in the 4-month-old Tmem135 TG mice than in age-matched WT mice at 600 and 900 µm away from the optic nerve.
In addition, utilizing the methods of Step 1 of the protocol, we calculated the incidence of RPE pathologies, including microvacuolization, macrovacuolization, and migration of three 25-day-old WT and Tmem135 TG mice (Figure 5A). The average frequency of RPE microvacuolization pathologies per slide in WT mice was 0.67 ± 0.31 and in Tmem135 TG mice was 7.07 ± 0.61 (Figure 5B). There was no RPE macrovacuolization in WT mice, but there were, on average, 5.33 ± 2.02 macrovacuolization events in Tmem135 TG mice (Figure 5C). Lastly, the rates of migratory RPE cells per slide was zero in WT mice and 0.4 ± 0.35 in Tmem135 TG mice (Figure 5D). After performing a student's t-test, the incidence of RPE microvacuolization and microvacuolization was significantly different between WT and Tmem135 TG mice. However, the higher incidence of RPE migratory cells in Tmem135 TG mice was not significantly different compared to WT (p = 0.1161). This data shows that RPE microvacuolization and macrovacuolization, but not migration, is significantly higher in 25-day-old Tmem135 TG than WT mice.
Following the methods of the protocol included in Step 2, we prepared retinal sections from 2-month-old and 24-month-old WT C57BL/6J mice for transmission electron microscopy to analyze the presence and heights of BLamDs. We found BLamDs present in 24-month-old WT retinas that were notably absent in 2-month-old WT retinas (Figure 6A). We presented the heights of the BLamDs in the 24-month-old WT retinas by calculating and plotting the cumulative frequencies of their occurrence. Cumulative frequencies of the BLamD heights were graphed against deposit height to illustrate the distribution of the deposit heights. There is a shift to the right of the line for the 24-month-old WT BLamD heights compared to the 2-month-old WT BLamD heights, demonstrating an increase of deposits in 24-month-old WT mice (Figure 6B). This graph is supported by a larger average of BLamD heights in 24-month-old WT retinas (1.01 μm ± 0.43 μm) than 2-month-old WT retinas (0.23 µm ± 0.017 μm), that were significantly different by a student's t-test (Figure 6C). In summary, we conclude that 24-month-old WT mice have large BLamDs in the sub-RPE space of their retinas compared to 2-month-old WT mice.
We applied the methods of preparing eyes from 4-month-old WT and Tmem135 TG mice in Step 3 to generate RPE flat mounts for the detection and analysis of RPE dysmorphia and multinucleation. In this protocol, we defined RPE dysmorphia by changes in RPE cell size and density in an AMD mouse model relative to their controls. We found that the RPE in 4-month-old Tmem135 TG mice are dysmorphic (Figure 7A). The RPE in Tmem135 TG retinas are larger (806.89 µm2 ± 252.67 vs. 291.69 µm2 ± 26.31) and less dense (0.0014 cells/µm2 ± 0.00039 vs. 0.0033 cells/µm2 ± 0.00024) than age-matched WT retinas (Figure 7B,C). Furthermore, there were more multinucleated RPE cells in the Tmem135 TG retinas compared to WT controls (8.04 cells ± 5.54 vs. 0.33 cells ± 0.29) (Figure 7D). All these parameters reached statistical significance with a student's t-test. Together, 4-month-old Tmem135 TG mice have more dysmorphic and multinucleated RPE cells than 4-month-old WT mice.
Figure 1: RPE pathologies detected by light microscopy. Representative images of normal RPE in WT (A) and abnormal RPE in Tmem135 TG mice (B-E). The RPE pathologies observed in Tmem135 TG mice include RPE thinning (B), macrovacuolization (C), microvacuolization (D), and migration (E). Each pathology is illustrated by a black arrow. Scale bar = 100 µm. Magnification = 20x. Abbreviations: RGC = retinal ganglion cell layer, IPL = inner plexiform layer, INL = inner nuclear layer, OPL = outer plexiform layer, ONL = outer nuclear layer, IS = photoreceptor inner segments, OS = photoreceptor outer segments, RPE = retinal pigmented epithelium, Cho = choroid. Please click here to view a larger version of this figure.
Figure 2: RPE pathologies detected by transmission electron microscopy. Representative images of (A) RPE in young CFH-H/H and (B) 2-year-old CFH-H/H mice that has abundant basal laminar deposits (BLamDs). BLamDs are traced with yellow dots in the image. Scale bar = 800 nm. Magnification = 15,000x. Abbreviations: N = nucleus, M = mitochondrion, P = pigment granule, BI = basal infoldings, EL = elastic lamina, RPE = retinal pigmented epithelium, BrM = Bruch's membrane, Cho = choroid. Please click here to view a larger version of this figure.
Figure 3: RPE pathologies detected by confocal microscopy. Representative images of (A) normal RPE of 8-month-old WT and (B) abnormal RPE of 8-month-old Tmem135 TG mice that exhibits RPE dysmorphia. The white square is zoomed in (C) to depict a multinucleated RPE cell with three nuclei. The green color is anti-ZO1 associated RPE tight junctions, and the blue color is DAPI staining of RPE nuclei. Scale bar = 50 µm. Magnification = 20x. Please click here to view a larger version of this figure.
Figure 4: RPE thickness in 4-month-old wild-type (WT) and Tmem135 TG mice. (A) Representative images of the retina from 4-month-old WT and Tmem135 TG (TG) mice. Magnification = 20x. Scale bar = 100 µm. (B) Line graphs of the RPE thickness measurements in 4-month-old WT (black) and Tmem135 TG mice (green) up to 3,000 µm away from the optic nerve. Numbers after the genotype denote the number of mice used in this study. *p < 0.05, ANOVA with post-hoc Tukey test. All data are mean ± sd. Please see the Figure 1 legend for abbreviations of retinal layers. Please click here to view a larger version of this figure.
Figure 5: RPE pathologies in 25-day-old Tmem135 TG mice. (A) Representative images of RPE microvacuolization, macrovacuolization, and migration in three 25-day-old Tmem135 TG (TG) mice. RPE pathologies are highlighted by black arrows in each image. Magnification = 40x. Scale bar = 20 µm. (B–D) Quantification of RPE micro- and macrovacuolization as well as migratory RPE cells in 25-day-old WT and Tmem135 TG mice. Numbers in parentheses denote the number of mice used in this study. *p < 0.05 and ****p < 0.0001, student's t-test. All data are mean ± sd. Please click here to view a larger version of this figure.
Figure 6: Ultrastructural analysis of BLamDs in young and aged WT retinas. (A) Representative electron micrographs of 2-month-old and 24-month-old WT RPE. Magnification = 15,000x. Scale bar = 800 nm. An example of a basal laminar deposit (BLamD) is diagrammed with a bracket. (B) Cumulative frequencies of the BLamD heights. (C) BLamD height averages. Numbers in parentheses denote the total number of mice per genotype used in this study. **p < 0.01, student's t-test. All data are mean ± sd. Please see the Figure 2 legend for abbreviations of retinal layers. Please click here to view a larger version of this figure.
Figure 7: RPE flat mounts reveal RPE pathologies in Tmem135 TG mice. (A) Representative images of 4-month-old WT and Tmem135 TG (TG) RPE flat mounts with anti-ZO-1 in green and DAPI in blue. Magnification = 20x. Scale bar = 100 µm. (B) RPE cell size, (C) RPE cell density, and (D) RPE multinucleation in 4-month-old WT and Tmem135 TG mice. The number in parentheses denotes the number of mice used in the study. *p < 0.05, **p < 0.01 and ****p < 0.0001, student's t-test. All data are mean ± sd. Please click here to view a larger version of this figure.
Supplementary Figure 1: Schematic of cardiac perfusion setup and use. (A) Gravity-feed perfusion system. (B) Syringe barrel of the perfusion system for fixative buffer. (C) Valve to be turned until it is parallel with the tubing line to allow the buffer to flow through the tubing line. (D) Valve to be turned until it is perpendicular with the tubing line to stop the buffer from flowing into the tubing line. Image created in Biorender. Please click here to download this File.
Supplementary Figure 2: Schematic of procedure for cardiac perfusion of a mouse. (A) Four incisions made to expose the abdominal cavity. (B) Cut made through the diaphragm and sternum to expose the heart. (C) Gauge needle inserted into the left ventricle of the heart. The valve is turned until it is parallel with the tubing line. The right atrium is cut with curved scissors to allow blood and fixative to exit. Image created in Biorender. Please click here to download this File.
Supplementary Figure 3: Schematic of procedure to enucleate eyes from a mouse. (A) Gently push down with the thumb and index finger around the eye socket to cause protrusion of the eye from the eye socket. (B) Take curved scissors and hold them with the blade at a 30° angle from the eye socket. Proceed to cut around the eye with the curved scissors at a 30° angle. Colored dots represent finger placement on the mouse or curved scissors. Image created in Biorender. Please click here to download this File.
Supplementary Figure 4: Pictures of mouse eye dissection to yield mouse posterior segment. (A) Eye transferred to a dissecting microscope. (B) Fat and muscle removed from the eyeball. (C) Cornea and iris removed from the eyeball. (D) Lens removed from the eyeball. Please click here to download this File.
Supplementary Figure 5: Hematoxylin eosin (H&E) staining procedure. Schematic depicting the H&E procedure to stain paraffin-embedded retinal sections. Arrows indicate transfer between steps. The time of each step is given in red font. Reagents for staining are provided in black font within glass staining containers. There should be a glass staining container prepared for each reagent that is included in the above diagram. All steps must be completed in a fume hood. When adding a coverslip to a slide, be careful not to introduce bubbles to the slide. After completion of the procedure, slides can be stored in a slide box. Image created in Biorender. Please click here to download this File.
Supplementary Figure 6: Example of RPE thickness measurement. The black arrow depicts a red line from the top to the bottom of the RPE. This line can be measured to determine the thickness of the RPE. Scale bar = 100 µm. Magnification = 20x. The boxed area is zoomed out for easier viewing of the RPE. Please see the Figure 1 legend for abbreviations of retinal layers. Please click here to download this File.
Supplementary Figure 7: EtOH dehydration procedure of mouse posterior segments for TEM processing. Image created in Biorender. Please click here to download this File.
Supplementary Figure 8: Example of BLamD height measurement. The red line depicts the largest BLamD in this image. Yellow dots delineate BLamDs in the image. This red line can be measured to determine the height of this BLamD in this image. Scale bar = 800 nm. Magnification = 15,000x. Please see the Figure 2 legend for abbreviations of retinal layers. Please click here to download this File.
Supplementary Figure 9: Mouse eye dissection for RPE flat mount. (A) Eye transferred to a Petri dish containing 1x PBS under a dissecting microscope. (B) Fat and muscle removed from the eyeball. (C) Cornea and iris removed from the eyeball. (D) Lens and retina removed from the eyeball. Please click here to download this File.
Supplementary Figure 10: Methanol (MeOH) fixation procedure of mouse posterior eyecups. Image created in Biorender. Please click here to download this File.
Supplementary Figure 11: Immunofluorescence procedure to label tight junctions and nuclei of RPE cells. Diagram depicting steps of immunofluorescence technique from this protocol. Note this technique takes 2 days to complete. All steps occur at RT and on a shaker with a speed of 75 rpm, unless specifically noted in the diagram. The primary (1°) antibody used in this study was rabbit polyclonal anti-ZO1, and the secondary (2º) antibody used in this study was 488 fluorophore-conjugated donkey anti-rabbit IgG. Once the secondary antibody and DAPI are added to the samples, then the samples must be wrapped in aluminum foil to protect against photobleaching of sample. Image created in Biorender. Abbreviations: NDS = normal donkey serum, Ab = antibody. Please click here to download this File.
Supplementary Figure 12: Depiction of cuts to yield four quadrants of mouse RPE flat mount. N = north, E = east, S = south, W = west. Please click here to download this File.
Supplementary Figure 13: Examples of RPE flat mount analysis endpoints. (A) RPE flat mount image. (B) RPE boundary trace image. (C) RPE Cell Profiler analyzed image. Magnification = 20x. Please click here to download this File.
Supplementary Coding File 1: Ikeda RPE Area Calculator.cpproj Please click here to download this File.
In this article, we introduced a phenotyping protocol for assessing the structural RPE pathologies of mouse models. We described the steps required for processing the eyes for various imaging techniques including light, transmission electron, and confocal microscopy, as well as the quantitation of typical pathologies observed via these imaging methods. We proved the effectiveness of our RPE phenotyping protocol by examining Tmem135 TG and 24-month-old WT mice, since these mice display RPE pathologies30,31,32. This protocol can be applied to any genetically modified or pharmacologically treated mouse that may harbor RPE pathologies such as RPE thinning, vacuolization, migration, and dysmorphia, as well as BLamDs6,7. Although the RPE pathologies observed in Tmem135 TG and 24-month-old WT mice are present in other AMD mouse models7,30, it is important for the researcher to become familiar with the AMD mouse model chosen for their studies, as the age of onset and severity of the RPE pathologies of their AMD mouse model may differ from the Tmem135 TG and 24-month-old WT mice. Researchers may need to utilize more mice for their studies than the numbers of mice used to produce the representative results shown in this article, if the presentation of RPE pathologies is variable in their respective AMD mouse model. Furthermore, many AMD mouse models are currently available to AMD researchers, yet do not have complete descriptions of their RPE pathologies, which may require researchers to perform preliminary studies to acquire this information.
Although modifications can be made in how mouse eyes are processed for the various imaging methods, it is critical to maintain the quantitative evaluation of structural RPE abnormalities as described in the protocol. For instance, five H&E-stained retinal sections were prepared to count the number of RPE microvacuolization, macrovacuolization, and migration events, allowing researchers to evaluate RPE pathologies at multiple locations in the mouse retina. Another example is using a 400-mesh thin-bar copper electron microscopy grid to assess the ultrastructural abnormalities of the RPE. The electron microscopy grid provides a framework to evaluate a retinal sample systematically and unbiasedly by transmission electron micrography, as well as obtain 40 to 70 images per retinal section to examine the presence of BLamDs. This cannot be achieved with an electron microscopy-slot grid, and we suggest not utilizing them with this protocol. Lastly, capturing 20x magnification images from the four quadrants of an RPE flat mount enables researchers to investigate large areas of murine RPE for dysmorphia and multinucleation. Researchers are free to expand on this protocol and examine additional retinal sections for RPE pathologies in their studies. Together, these methods allow researchers to gather ample data to make conclusions about the structural RPE pathologies that may be present in their AMD mouse models.
Another key feature of this protocol is the consistency of the RPE phenotyping methods. For example, all eyes used for light and transmission electron microscopy were orientated by the superior side of the mouse retina for sectioning. It is important to maintain the orientation of the mouse eye throughout its processing for light and transmission electron microscopy because the mouse eye has a topographical distribution of retinal cells33,34. The anatomical orientation of the mouse eye was not maintained for RPE flat mount preparation, since superior to inferior topographical changes of the mouse RPE cell have not been observed. In fact, the RPE in the human retina displays topographical changes that radiate away from the optic nerve head35, suggesting this may be the case for mouse RPE. Lastly, the image acquisition described in this protocol relies on the anatomical positioning of the optic nerve. Inclusion of these methodological aspects will help to reproduce results of RPE pathologies for researchers as they work with their AMD mouse models.
Researchers may desire to add more analytical features to the RPE phenotyping protocol. Some phenotypic outcomes not featured in this protocol are the examination of BrM thickness, RPE apical microvilli, and other RPE ultrastructural components. These components include mitochondria, pigment granules, and other organelles like phagosomes. Researchers can determine the size and number of these components in the electron micrographs obtained with this protocol using the Fiji ImageJ program. In particular, the status of mitochondria may be an important phenotypic outcome to consider, since targeting mitochondria in the RPE is an important therapeutic strategy for AMD36. Another phenotypic outcome is additional measurements of RPE dysmorphia on RPE flat mounts. RPE flat mount images obtained using the protocol can be examined for RPE hexagonal shape, number of neighboring RPE cells, and other properties with the REShAPE program (https://github.com/nih-nei/REShAPE)35. Another possible phenotypic outcome is whether RPE pathologies occur in the central or peripheral areas of the mouse retina. These additional phenotypic considerations will further strengthen the RPE phenotyping protocol described in this article.
There are a few limitations of this RPE phenotyping protocol. One limitation of this method is the need to sacrifice mice to harvest their eyes for RPE phenotyping. As an alternative, new advances in spectral domain optical coherence tomography (SD-OCT) imaging allow for the quantification of RPE thickness and pathologies in living mice37–39. This may be advantageous to researchers who want to perform longitudinal studies on their AMD mouse model cohorts. Another limitation of this method is the lack of functional RPE assessments in mice. If researchers are interested in a functional assessment of the RPE in mice, we recommend performing electroretinography and measuring the c-wave component, as the c-wave is indicative of the functional role of the RPE in phototransduction40. Another limitation of this method is the lack of biochemical measurements of RPE markers in mice. If researchers desire to investigate the levels of RPE markers, such as cellular retinaldehyde-binding protein (CRABLP), retinal pigment epithelium-specific 65 kDa protein (RPE65), potassium inwardly rectifying channel subfamily J member 13 (KCNJ13), or bestrophin 1 (BEST1), we recommend harvesting eyes for immunohistochemistry, quantitative real-time PCR, or western blot analysis.
In conclusion, this RPE phenotyping protocol can be an important resource for researchers using mouse models recapitulating pathological aspects of AMD. This protocol also serves to standardize how the RPE is evaluated in AMD mouse models, which has not been previously described in the literature. Standardizing RPE phenotyping would be critical in translating the findings from mice to other models of AMD, including RPE cell culture models4 and higher organism models including non-human primates. It would also aid in our understanding of the pathobiological mechanisms underlying AMD development and potentially developing new therapies for this blinding disease.
The authors have nothing to disclose.
The authors would like to acknowledge Satoshi Kinoshita and the University of Wisconsin (UW) Translational Research Initiatives in Pathology laboratory (TRIP) for preparing our tissues for light microscopy. This core is supported by the UW Department of Pathology and Laboratory Medicine, University of Wisconsin Carbone Cancer Center (P30 CA014520), and the Office of The Director-NIH (S10OD023526). Confocal microscopy was performed at the UW Biochemistry Optical Core, which was established with support from the UW Department of Biochemistry Endowment. This work was also supported by grants from the National Eye Institute (R01EY022086 to A. Ikeda; R01EY031748 to C. Bowes Rickman; P30EY016665 to the Department of Ophthalmology and Visual Sciences at the UW; P30EY005722 to the Duke Eye Center;NIH T32EY027721 to M. Landowski; F32EY032766 to M. Landowski), Timothy William Trout Chairmanship (A. Ikeda), FFB Free Family AMD Award (C. Bowes Rickman); and an unrestricted grant from the Research to Prevent Blindness (Duke Eye Center).
0.1 M Cacodylate Buffer pH7.2 | PolyScientiifc R&D Company | S1619 | |
100 Capacity Slide Box | Two are needed for this protocol (one for H&E-stained slides and one for RPE flat mounts.) | ||
100% Ethanol | MDS Warehouse | 2292-CASE | Can be used to make diluted ethanol solutions in this protocol. |
1-Way Stopcock, 2 Female Luer Locks | Qosina | 11069 | |
1x Phosphate Buffer Solution (PBS) | Premade 1x PBS can be used in this protocol. | ||
2.0 mL microtubes | Genesee Scientific | 24-283-LR | |
24 Cavity Embedding Capsule Substitute Mold | Electron Microscopy Sciences | 70165 | |
24 inch PVC Tubing with Luer Ends | Fisher Scientific | NC1376778 | |
400 Mesh Gilder Thin Bar Square Mesh Grids | Electron Microscopy Sciences | T400-Cu | |
95% Ethanol | MDS Warehouse | 2293-CASE | |
Absorbent Underpads with Waterproof Moisture Barrier (23 inches by 24 inches) | VWR | 56616-031 | |
Adjustable 237 ml Spray Bottle | VWR | 23609-182 | |
Alexa Fluor488 Conjugated Donkey anti-Rabbit IgG | Thermo Fisher Scientific | A-21206 | |
Aluminum Foil | |||
BD Precision glide 19 Gauge Syringe Needle | Sigma-Aldrich | Z192546 | |
Bracken Forceps; Curved; Fine Cross Serrations; 4" Length, 1 mm Tip Width | Roboz Surgical Instrument | RS-5211 | Known as curved forceps in this protocol. |
Camel Hair Brush | Electron Microscopy Sciences | 65575-02 | |
Carbon Dioxide Euthanasia Chamber | |||
Carbon Dioxide Flow Meter | |||
Carbon Dioxide Tank | |||
Castaloy Prong Extension Clamps | Fisher Scientific | 05-769-7Q | |
Cast-Iron L-shaped Base Support Stand | Fisher Scientific | 11-474-207 | |
Cell Prolifer Program | Available to download: https://cellprofiler.org/releases | ||
Clear Nail Polish | Electron Microscopy Sciences | 72180 | |
Colorfrost Microscope Slides Lavender | VWR | 10118-956 | |
Computer | |||
DAPI | Sigma-Aldrich | D9542-5MG | |
Distilled H20 | Water from Milli-Q Purification System was used in this protocol. | ||
Dumont Thin Tip Tweezers; Pattern #55 | Roboz Surgical Instrument | RS-4984 | Known as fine-tipped forceps in this protocol, and 3 are needed for this protocol (two for dissections and one for electron microscope processing). |
Electron Microscopy Grid Holder | Electron Microscopy Sciences | 71147-01 | |
EPON 815 Resin | Electron Microscopy Sciences | 14910 | |
Epredia Mark-It Tissue Marking Yellow Dye | Fisher Scientific | 22050460 | Please follow manufacturer's protocol when using this tissue marking dye. |
Epredia Mounting Media | Fisher Scientific | 22-110-610 | Use for mounting H&E slides. |
Fiber-Lite Mi-150 Illuminator Series,150 w Halogen Light Source | Dolan-Jenner Industries | Mi-150 | Light source for dissecting microscope. |
Fiji ImageJ Program | Available to download: https://imagej.net/downloads | ||
Flexaframe Castaloy Hook Connector | Thermo Scientific | 14-666-18Q | |
Fume hood | |||
Glutaraldehyde 2.5% in Phosphate Buffer, pH 7.4, 32% | Electron Microscopy Sciences | 16537-05 | |
JEM-1400 Transmission Electron Microscope (JEOL) with an ORIUS (1000) CCD Camera | |||
Laboratory Benchtop Shaker | Two are needed for these experiments. One should be at room temperature while the other should be in a 4 degree Celsius cold room. | ||
Laser Cryo Tag Labels | Electron Microscopy Sciences | 77564-05 | |
Lead Citrate | Electron Microscopy Sciences | 17800 | |
Leica EM UC7Ultramicrotome | |||
Leica Reichert Ultracut S Microtome | |||
LifterSlips | Thermo Fisher Scientific | 22X22I24788001LS | Use these coverslips for the RPE flat mounts as they have raised edges and accommodate the thickness of the RPE. |
Mayer's Hematoxylin | VWR | 100504-406 | |
McPherson-Vannas Micro Dissecting Spring Scissors | Roboz Surgical Instrument | RS-5600 | Known as micro-dissecting scissors in protocol. |
Methanol | Fisher Scientific | A412-4 | |
Mice | Any AMD mouse model and its respective controls can work for this protocol. | ||
Micro Dissecting Scissors; Standard Version; Curved; Sharp Points; 24 mm Blade Length; 4.5" Overall Length | Roboz Surgical Instrument | RS-5913 | Known as curved scissors in this protocol. |
Microsoft Excel | |||
Microtube racks | |||
Nikon A1RS Confocal Microscope | |||
Normal Donkey Serum | SouthernBiotech | 0030-01 | |
Number 11 Sterile Disposable Scalpel Blades | VWR | 21909-380 | |
Osmium Tetroxide | Electron Microscopy Sciences | 19150 | |
Paraformaldehyde, 32% | Electron Microscopy Sciences | 15714-S | |
Pencil | |||
Petri Dish | VWR | 21909-380 | |
Pipette Tips | |||
Pipettes | |||
Polyclonal Anti-ZO-1 Antibody | Thermo Fisher Scientific | 402200 | |
Propylene Oxide | Electron Microscopy Sciences | 20412 | |
Razor Blade | VWR | 10040-386 | |
Shallow Tray for Mouse Perfusions | |||
Shandon Eosin Y Alcoholic | VWR | 89370-828 | |
Sharpie Ultra Fine Tip Black Permanent Marker | Staples | 642736 | |
Slide Rack for Staining | Grainger | 49WF31 | |
Squared Cover Glass Slips | Fisher Scientific | 12-541B | |
Staining Dish with Cover | Grainger | 49WF30 | Need 15 for H&E staining procedure. |
Target All-Plastic Disposable Luer-Slip 50 mL Syringe | Thermo Scientific | S7510-50 | Use only the syringe barrel. |
Timer | Fisher | 1464917 | |
Uranyl Acetate | Electron Microscopy Sciences | 22400 | |
Vacuum Oven | |||
Vectashield Mounting Medium | Vector Laboratories | H-1000 | Use for mounting RPE flat mounts. |
Xylene | Fisher Scientific | 22050283 | |
Zeiss Axio Imager 2 Light Microscope | This microscope has the capacity to generate stitched 20x images. If a light microscope does not have this capacity, then take images of the entire retina that are slightly overlapping each other. Use Adobe Photoshop to stitch these images together. Please refer to the manuals of the Adobe Photoshop program for image stitching. | ||
Zeiss Stemi 2000 Dissecting Microscope | Electron Microscopy Sciences | 65575-02 |