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Lanny Shulman, Samuel Hanlon, Paul Landry, Clifton Smith, Alan Burns; Changes in Mouse Corneal Epithelial Innervation After Injury. Invest. Ophthalmol. Vis. Sci. 2013;54(15):3913. doi: https://doi.org/.
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Corneal epithelial abrasion is associated with nerve injury and while nerve regeneration in the mouse model can occur quickly, with nerve density recovering by 6 weeks post-injury, the pattern of the subbasal nerve plexus is abnormal. Whether nerve regeneration involves a change in the number of epithelial leashes and their distribution is unclear. An epithelial leash is defined as a group of subbasal nerves originating from a deeper stromal nerve. The purpose of this study is to provide a more detailed analysis of epithelial leash number and distribution following a central epithelial corneal abrasion.
Anesthetized adult C57BL/6 mice ages 8-10 weeks received 2.0 mm wide central corneal epithelial abrasions with an Alger brush. Uninjured age-matched mice served as controls. Mice were euthanized at 2, 4, and 6 weeks post-injury and corneas were excised, fixed and incubated in neuronal specific β-III Tubulin tagged with phycoerythrin; DAPI staining was used to identify cell nuclei. Using a DeltaVision fluorescence microscope, corneal wholemounts were partitioned into three concentric circular zones: a central 1600 μm diameter zone, a middle zone extending approximately 800 μm and a peripheral 480 μm zone. Epithelial leash number and distribution were evaluated using Image J software and a custom Matlab program.
In the uninjured cornea, epithelial leashes were generally confined to the middle (72 ±12) and peripheral zones (17 ±3); very few leashes were detected in the central zone (6 ±4). At 2 weeks post-injury, epithelial leash counts in the central zone increased 4-6 fold over age-matched controls and remained elevated at 4 and 6 weeks post-injury. In contrast, there was no significant change in the number of leashes in the middle and peripheral zones at 2, 4 or 6 weeks post-injury.
The data suggest that following a central epithelial abrasion, the greatest increase in epithelial leashes occurs in the central zone, which prior to injury had very few leashes. The de novo appearance of epithelial leashes in the central zone contributes to the abnormal patterning of the regenerating subbasal nerve plexus.
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