Neovascularization (NV) of the cornea can complicate multiple visual pathologies. Utilizing a controlled, alkali-burn injury model, a quantifiable level of corneal NV can be produced for mechanistic study of corneal NV and evaluation of potential therapies for neovascular disorders.
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Method Article
An Alkali-burn Injury Model of Corneal Neovascularization in the Mouse
* These authors contributed equally
In This Article
Summary
Abstract
Under normal conditions, the cornea is avascular, and this transparency is essential for maintaining good visual acuity. Neovascularization (NV) of the cornea, which can be caused by trauma, keratoplasty or infectious disease, breaks down the so called ‘angiogenic privilege' of the cornea and forms the basis of multiple visual pathologies that may even lead to blindness. Although there are several treatment options available, the fundamental medical need presented by corneal neovascular pathologies remains unmet. In order to develop safe, effective, and targeted therapies, a reliable model of corneal NV and pharmacological intervention is required. Here, we describe an alkali-burn injury corneal neovascularization model in the mouse. This protocol provides a method for the application of a controlled alkali-burn injury to the cornea, administration of a pharmacological compound of interest, and visualization of the result. This method could prove instrumental for studying the mechanisms and opportunities for intervention in corneal NV and other neovascular disorders.
Introduction
Corneal blindness is the fourth most common cause of blindness, responsible for approximately 4% of all cases1. Corneal neovascularization (NV) plays a significant role in many of these pathologies, including herpetic keratitis (the leading infectious cause of blindness in the West) and trachoma (the leading cause of infectious blindness worldwide)2. Current therapies include steroids, nonsteroidal anti-inflammatory drugs (NSAIDs), anti-VEGF therapies, and cyclosporin A as well as conventional or laser surgical techniques3. However, the severely debilitating nature of corneal NV based pathologies, the paucity of surgical facilities cap....
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Protocol
Note: The following protocol and representative results use the HDAC inhibitor SAHA as an example compound. However, this protocol is by no means limited to the use of SAHA, and is recommended as a general method to test the effects of soluble compounds on corneal neovascularization. Minor modifications will need to be made for degree of dilution as well as frequency and duration of application. Additionally, compounds that are easily soluble in water will be able to be administered in the absence of DMSO.
Ethical Statement: All animal experiments should only be performed in compliance with national law and institutional regulations. This p....
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Results
After alkali-burn injury, corneal NV occurs in a predictable, time-dependent fashion. Figure 1 demonstrates the stark difference both in neovascularization and corneal opacity between an untreated animal (Figure 1A) and an animal treated with the HDAC inhibitor SAHA (Figure 1B) at the 7 day time point.
Figures 2A and 2B demonstrate a corneal flat mount of an untreated control eye with primary PECAM-1 and LYVE-.......
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Discussion
The protocol presented here results in reproducible levels of hemangiogenesis, lymphangiogenesis, and inflammation, making it an ideal system to study these three (interrelated) processes. While this method produces centralized corneal NV, several methods that have been developed to cause more directed NV, namely suturing of the cornea17 and implanted growth-factor expressing pellets18, might also be of interest. Our protocol is designed for use in the adult mouse, providing an easy to use anim.......
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Disclosures
The authors have nothing to disclose.
Acknowledgements
We are grateful for Dr. Xinyu Li's help in preparing the manuscript. S.W. was supported by a Startup fund from Tulane University, President's Research Council New Investigator Award from UT Southwestern Medical Center, NIH Grant EY021862, a career development award from the Research to Prevent Blindness foundation, and a Bright Focus Award in Age Related Macular Degeneration Research.
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Materials
| Name | Company | Catalog Number | Comments |
|---|---|---|---|
| 1 ml Syringe | BD | 309659 | |
| 18 G Needle | BD | 305918 | |
| 10 ml Syringe | BD | 306575 | |
| 25 G Needle | BD | 305916 | |
| Anti-F4/80 (rat anti-mouse) | AbD Serotech | MCA497RT | |
| Anti-LYVE-1 (rabbit anti-mouse) | Abcam | ab14917 | |
| Anti-PECAM-1 (rat anti-mouse) | BD | 553370 | |
| Anti-IgG Alexa 488 (goat anti-rat) | Invitrogen | A11006 | |
| Anti-IgG Alexa 594 (goat anti-rabbit) | Invitrogen | A11012 | |
| Camera | Tucsen | TCC 5.0 ICE | |
| Coverslips | Fisher | 12-548-B | |
| DMSO | Sigma | D4540-1L | Caution: Mutagenic, Toxic |
| Forceps (Blunt), Iris | WPI | 15915 | |
| Forceps (Sharp), Dumont #4 | WPI | 500340 | |
| KCl | Fisher | P217-500 | |
| Ketamine Solution | MedVet | RXKETAMINE | Controlled substance, proper license required for use. |
| Light Source for Microscope | AmScope | LED-14M-YA | |
| Microscope (Stereo 7X-45X) | AmScope | SM-1B | |
| Mounting Medium, VECTASHIELD | Vector | H-1000 | |
| NaCl | Fisher | S271-10 | |
| NaH2PO4 | Fisher | S397-500 | |
| NaOH | Fisher | S318-1 | Caution: Corrosive |
| Paraformaldehyde | P6148-500G | Caution: Allergenic, Carcenogenic, Toxic | |
| Proparacaine Hydrochloride | Sigma | P4554-1G | |
| Scissors (5 mm blade), Vanas | WPI | 14003 | |
| Goat Serum | MPBio | 92939249 | |
| Microscope Slides | Fisher | 12-550-15 | |
| Triton X-100 | Sigma | T8787-100ML | |
| Whatman Grade 1 Filter Paper | Whatman | 1001-6508 | |
| Xylazine Solution | MedVet | RXANASED-20 |
References
- Pascolini, D., Mariotti, S. Global estimates of visual impairment. Br. J. Ophthalmol. 96 (5), 614-618 (2010).
- Whitcher, J., Srinivasan, M., Upadhyay, M. Corneal Blindness: A Global Perspective. Bull. World Health Org. 79 (3), 214-221 (2003).
- Gupta, D., Illingworth, C.
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