Apr 07, 2023

Fixation and Embedding of Eyes at UAB

 Forked from Fixation of Eyes at UAB
DOI
https://dx.doi.org/10.17504/protocols.io.8epv5jp75l1b/v1
  • 1University of Alabama at Birmingham;
  • 2Vanderbilt University
  • VU Biomolecular Multimodal Imaging Center / Spraggins Research Group
  • Human BioMolecular Atlas Program (HuBMAP) Method Development Community
Angela R.S. Kruse
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DOI: https://dx.doi.org/10.17504/protocols.io.8epv5jp75l1b/v1
Protocol Citation: Jeffrey D. Messinger, David Anderson, Angela Kruse, Jamie Allen, melissa.a.farrow , Jeff Spraggins, Kevin Schey, Christine Curcio 2023. Fixation and Embedding of Eyes at UAB. protocols.io https://dx.doi.org/10.17504/protocols.io.8epv5jp75l1b/v1
Manuscript citation:
Anderson DMG, Messinger JD, Patterson NH, Rivera ES, Kotnala A, Spraggins JM, Caprioli RM, Curcio CA, Schey KL. 2020. Lipid Landscape of the Human Retina and Supporting Tissues Revealed by High Resolution Imaging Mass Spectrometry. bioRxiv:2020.2004.2008.029538.
Pang CE, Messinger JD, Zanzottera EC, Freund KB, Curcio CA. 2015. The Onion Sign in Neovascular Age-Related Macular Degeneration Represents Cholesterol Crystals. Ophthalmology 122:2316-2326..
License: This is an open access  protocol  distributed under the terms of the  Creative Commons Attribution License,  which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
Protocol status: Working
We use this protocol and it's working
Created: March 27, 2023
Last Modified: October 18, 2023
Protocol  Integer ID: 79505
Keywords: HuBMAP, BIOMIC, Vanderbilt, University of Alabama, Eye, Fixation, fixation of whole human eye, eyes at uab, whole human eye, part of the human biomolecular atlas project, human biomolecular atlas project, eye, fixation, uab
Abstract
The accession and fixation of whole human eye specimens at University of Alabama Birmingham as part of the Human Biomolecular Atlas Project.
Materials
tissue marking dyes (Cancer Diagnostics Inc. Durham, NC)
18-mm trephine, Stratis Healthcare, #6718L
Curved Spring Scissors, Roboz Cat# RS-5681
4% Paraformaldehyde, EMS Cat#15713-S
Sorenson’s Phosphate Buffer (EMS Cat# 11600-10)
Fixation container (Fisher ScientificTM SamecoTMBio-TiteTM40 ml Cat# 13-711-86)
1 mm ruby bead (Meller Optics Cat# MRB10MD)
embedding molds (Peel-A-Way 22 x 30 mm molds, Polysciences # 18646B)
Bitran Freezer Bag (Fisher Science cat# 19240150)
Collection, dissection, and preservation of ocular tissue
Whole donor globes on wet ice were received within less than 6 hours time of death (TOD) from the Advancing Sight Network (500 Robert Jemison Rd Birmingham, AL 35209). Laterality was verified using extra ocular anatomy.
Tissue orientation was preserved using tissue marking dyes in (Cancer Diagnostics Inc. Durham, NC) black, red, and, yellow identifying the superior rectus muscle, fovea, and optic nerve head respectively.

Figure 1: Posterior view of excised ocular globes, as if one is standing behind the patient. The superior portion of the eye is marked in black. The yellow marker demonstrates the location of the optic nerve head (ONH). The red marker demonstrates the approximate location of the fovea. Superior, inferior, nasal and temporal (S, I, N, T) refer to the 4 ocular quadrants. The long posterior ciliary artery divides the superior and inferior hemisphere.
To facilitate removal of the cornea and preservative penetration, a circular cut was scored through the Ora Serrata using an 18-mm trephine (Stratis Healthcare, #6718L) and a small 3 x 5 mm rectangular window incision was made at the scleral-cornea junction by first making a small (~5mm) incision with a scalpel or similar, then completing a rectangular incision area with curved spring scissors (Roboz Cat# RS-5681).

Figure 2: Incisions made in anterior portion of eye to facilitate separation of the anterior and posterior segments as well as preservative penetration.

The globe with incisions described in step 3 is immersed in immersed in ice-cold 4% paraformaldehyde (EMS Cat#15713-S) in Sorenson’s Phosphate Buffer, 0.1M pH 7.2 (EMS Cat# 11600-10) and allowed to fix for 24 hours at 4°C.

After 24 hours, the anterior portion was removed using the trephine-scored incision described in step 3.

Color fundus photography
After 24 hours, globes are placed within a 30 cc quartz crucible (Fisher Scientific # 08-074D) in correct anatomical orientation (aka facing the patient). Size was referenced using a 1 mm diameter ruby bead (Meller Optics Cat# MRB10MD). Color fundus photographs were obtained using a Nikon D7200 DSLR camera mounted to an Olympus SZX9 stereo microscope at 3 magnifications (0.75x, 1.50x, and 3.00x) with 3 modalities of epi, flash, and trans illuminations.

Figure 3: Color fundus photographs. Epi, flash, and trans illumination (left, middle, and right, respectively) was used to image the ocular fundus at 0.75x, 1.50x, and 3x magnifications (top, middle, and bottom, respectively).

Optical coherence tomography (OCT)
Optical coherence tomography (OCT) images of globes were collected using a Spectralis Spectral Domain OCT (HRA&OCT, HRA2; Heidelberg Engineering) as follows:
Globes are immersed in chilled Sorenson's buffer with the anterior orientation facing the objective lens of the OCT device within a custom-built chamber with a 60-diopter lens (Pang et al., 2015)
Figure 4. Custom-built OCT chamber containing globe with anterior orientation facing toward the objective lens (right)
Spectral domain OCT was acquired with the following parameters:
30° macula cube
30 μm spacing
Automatic Real-time averaging ≥50
Near-infrared reflectance, red-free reflectance, and autofluorescence (488 nm excitation wavelength) modalities
Tissue orientation and embedding
Orient the posterior portion of the eye in a cryomold (Peel-A-Way 22 x 30 mm molds, Polysciences # 18646B) with the assistance of a stereo microscope (Nikon SMZ 1000 or similar), as follows:

Using a razor blade or similar, carefully remove the bottom of one cryomold. Place within a second cryomold to create a double-stack.

Label double-stacked cryomolds corresponding to the tissue orientation denoted by the tissue marking dyes.

Prefill the bottom of the mold with 5 ml of 15% fish gelatin.

Place the superior pole (black tissue mark) along the mold side with the fundus facing directly upwards.

The optic nerve head (ONH) and fovea (yellow and red tissue marks, respectively) are placed on the bottom of the mold. Label the bottom of the mold with their locations.

Figure 5: A. Double-stacked cryomold containing globe stabilized in small amount of fish gelatin. B. Bottom of mold indicating location of optic nerve head (ONH) and fovea (F). C. Top of mold indicating orientation of embedded globe (fundus facing upward, superior orientation indicated by black dye).
With the tissue oriented as in step 7.

Allow gelatin to semi-freeze by holding the mold suspended in liquid nitrogen until semi-solid and tacky to ensure stable positioning of the posterior pole in the cryomold. Use forceps to suspend mold within liquid nitrogen in dewar.

Slowly fill the fundus first with 15% fish gelatin and allow the fish gelatin to overflow out of the fundus cup until the entire mold is filled

Freeze the mold and tissue with liquid nitrogen, but do not let liquid nitrogen flow over the top of the mold.

Store in a -80oC freezer in a Bitran Freezer Bag (Fisher Science cat# 19240150) until shipment.
Label one additional cryomold for anterior portion (removed in step 4), indicating the location of the superior pole (black tissue marking dye). Optionally, draw the shape of the cornea on the side of the mold.

Prefill the mold with 5 ml of 15% fish gelatin.

Place anterior pole in mold with the cornea facing down.

Allow gelatin to semi-freeze until semi-solid and tacky in liquid nitrogen to ensure tissue adherence. Use forceps to suspend mold within liquid nitrogen in dewar.

Completely fill mold with 15% fish gelatin.

Freeze entire mold with liquid nitrogen, but do not let liquid nitrogen flow over the top of the mold.

Store in a -80oC freezer in a Bitran Freezer Bag (Fisher Science cat# 19240150) for shipment to Vanderbilt University.