Optimization of the Retinal Vein Occlusion Mouse Model to Limit Variability

Summary

Here, we describe an optimized protocol for retinal vein occlusion using rose bengal and a laser-guided retinal imaging microscope system with recommendations to maximize its reproducibility in genetically modified strains.

Abstract

Mouse models of retinal vein occlusion (RVO) are often used in ophthalmology to study hypoxic-ischemic injury in the neural retina. In this report, a detailed method pointing out critical steps is provided with recommendations for optimization to achieve consistently successful occlusion rates across different genetically modified mouse strains. The RVO mouse model consists primarily of the intravenous administration of a photosensitizer dye followed by laser photocoagulation using a retinal imaging microscope attached to an ophthalmic guided laser. Three variables were identified as determinants of occlusion consistency. By adjusting the wait time after rose bengal administration and balancing the baseline and experimental laser output, the variability across experiments can be limited and a higher success rate of occlusions achieved. This method can be used to study retinal diseases that are characterized by retinal edema and hypoxic-ischemic injury. Additionally, as this model induces vascular injury, it can also be applied to study the neurovasculature, neuronal death, and inflammation.

Introduction

Retinal vein occlusion (RVO) is a common retinal vascular disease that affected approximately 28 million people worldwide in 2015¹. RVO leads to vision decline and loss in working aged adults and elders, representing an ongoing sight-threatening disease estimated to increase over the proximate decade. Some of the distinct pathologies of RVO include hypoxic-ischemic injury, retinal edema, inflammation, and neuronal loss². Currently, the first line of treatment for this disorder is through the administration of vascular endothelial growth factor (VEGF) inhibitors. While anti-VEGF treatment has helped ameliorate retinal ede....

Protocol

This protocol follows the Association for Research in Vision and Ophthalmology (ARVO) statement for the use of animals in ophthalmic and vision research. Rodent experiments were approved and monitored by the Institutional Animal Care and Use Committee (IACUC) of Columbia University.

NOTE: All experiments used two-month-old male mice that weighed approximately 20 g.

1. Preparation and administration of tamoxifen for inducible genetic ablation of floxed genes

NOTE: Retinal vessel diameter can be affected by the weight of the animal. Make sure that all animals used for an experiment are of ....

Results

The RVO mouse model aims to successfully achieve occlusions in the retinal veins, leading to hypoxic-ischemic injury, breakdown of the blood retinal barrier, neuronal death, and retinal edema⁸. Figure 1 shows a timeline of steps to ensure reproducibility, a schematic of the experimental design, and outlines steps that can be further optimized depending on the experimental questions. The three main steps that can be modified are the waiting time after rose bengal admin.......

Discussion

The mouse RVO model provides an avenue to further understand RVO pathology and to test potential therapeutics. While the mouse RVO model is widely used in the field, there is a need for a current detailed protocol of the model that addresses its variability and describes the optimization of the model. Here, we provide a guide with examples from experience on what can be altered to get the most consistent results across a cohort of experimental animals and provide reliable data.

The two most es.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Carprofen	Rimadyl	NADA #141-199	keep at 4 °C
Corn Oil	Sigma-Aldrich	C8267
Fiber Patch Cable	Thor Labs	M14L02
GenTeal	Alcon	00658 06401
Ketamine Hydrochloride	Henry Schein	NDC: 11695-0702-1
Lasercheck	Coherent	1098293
Phenylephrine	Akorn	NDCL174478-201-15
Phoneix Micron IV with Meridian,  StreamPix, and OCT modules	Phoenix Technology Group
Proparacaine Hydrochloride	Akorn	NDC: 17478-263-12	keep at 4 °C
Refresh	Allergan	94170
Rose Bengal	Sigma-Aldrich	330000-5G
Tamoxifen	Sigma-Aldrich	T5648-5G	light-sensitive
Tropicamide	Akorn	NDC: 174478-102-12
Xylazine	Akorn	NDCL 59399-110-20