Müller Glia Cell Activation in a Laser-induced Retinal Degeneration and Regeneration Model in Zebrafish

Summary

The zebrafish is a popular animal model to study mechanisms of retinal degeneration/regeneration in vertebrates. This protocol describes a method to induce localized injury disrupting the outer retina with minimal damage to the inner retina. Subsequently, we monitor in vivo the retinal morphology and the Müller glia response throughout retinal regeneration.

Abstract

A fascinating difference between teleost and mammals is the lifelong potential of the teleost retina for retinal neurogenesis and regeneration after severe damage. Investigating the regeneration pathways in zebrafish might bring new insights to develop innovative strategies for the treatment of retinal degenerative diseases in mammals. Herein, we focused on the induction of a focal lesion to the outer retina in adult zebrafish by means of a 532 nm diode laser. A localized injury allows investigating biological processes that take place during retinal degeneration and regeneration directly at the area of damage. Using non-invasive optical coherence tomography (OCT), we were able to define the location of the damaged area and monitor subsequent regeneration in vivo. Indeed, OCT imaging produces high-resolution, cross-sectional images of the zebrafish retina, providing information which was previously only available with histological analyses. In order to confirm the data from real-time OCT, histological sections were performed and regenerative response after the induction of the retinal injury was investigated by immunohistochemistry.

Introduction

Vision is probably the most essential sense of the human being and its impairment has a high socio-economic impact. In the industrialized world, retinal degenerative diseases account for the majority of vision loss and blindness among the adult population¹. Retinitis pigmentosa (RP) is the most common inherited cause of blindness in people between the ages of 20 and 60, affecting approximately 1.5 million people worldwide^2,3. It is a heterogeneous family of inherited retinal disorders characterized by progressive loss of the photoreceptors (PRs) followed by degeneration of retinal pigme....

Protocol

All experiments adhered to the Statement for the Use of Animals in Ophthalmic and Vision Research of the Association for Research in Vision and Ophthalmology (ARVO) and respect the related regulations of the governmental authorities.

1. Animals

1. Maintain TgBAC (gfap:gfap-GFP) zebrafish 167 (AB) strain aged between 6 - 9 months under standard conditions in water with a temperature of 26.5 °C and a 14/10 h light/dark cycle¹⁸.
2. Follow the animal care guidelines of the involved institutions for the animal experiments after approval by the governmental authorities.

Results

Real-time OCT: In order to analyze the role of MCs in retinal repair, we used a laser injury model inducing a well-delineated zone of damage in the zebrafish retina. The site of damage was imaged by means of in vivo OCT for the first time (Day 0) within 60 minutes following the injury (Figure 3). To compensate for the optics of the fish eye, a custom-made contact lens was placed on the cornea. Immediately after laser treatment, a dif.......

Discussion

Retinal regeneration/degeneration in the zebrafish has been investigated by different approaches such as cytotoxin-mediated cell death²², mechanical injury²³, and thermal injury²⁴. We employed a 532 nm diode laser to damage the zebrafish retina. Thereby, our model offers several advantages. For instance, we rapidly created a well-defined area of injury localized in the outer retina, specifically in the PRs layer. Furthermore, this experimental set-up.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Acid hematoxylin solution	Sigma-Aldrich, Buchs, Switzerland	2852
Albumin	Sigma-Aldrich, Buchs, Switzerland	A07030
Bovine serum albumin (BSA)	Sigma-Aldrich, Buchs, Switzerland	5470
Dako Pen	Dako, Glostrup, Danmark	S2002
DAPI mounting medium	Vector Labs, Burlingame, CA, USA	H-1200
Eosin G aqueous solution 0.5%	Carl Roth, Arlesheim, Switzerland	X883.2
Ethanol	Sigma-Aldrich, Buchs, Switzerland	2860
Ethylene diamine tetraacetic acid (EDTA)	Sigma-Aldrich, Buchs, Switzerland	ED
Eukitt	Sigma-Aldrich, Buchs, Switzerland	3989
Goat anti-rabbit IgG H&L Alexa Fluor® 488	Life Technologies, Zug, Switzerland	A11008
Goat anti-mouse IgG H&L Alexa Fluor® 594	Life Technologies, Zug, Switzerland	A11020
Goat normal serum	Dako, Glostrup, Danmark	X0907
Hydrogel contact lens	Johnson & Johnson AG, Zug, Switzerland	n.a.	1-Day Acuvue Moist
Hydroxypropylmethylcellulose 2%	OmniVision, Neuhausen, Switzerland	n.a.	Methocel 2%
Ethyl 3-aminobenzoate methanesulfonate	Sigma-Aldrich, Buchs, Switzerland	A5040	Tricaine, MS-222
Visulas 532s	Carl Zeiss Meditec AG, Oberkochen, Germany	n.a.	532 nm laser
Mouse anti-GS monoclonal antibody	Millipore, Billerica, MA, USA	MAB302
HRA + OCT Imaging System	Heidelberg Engineering, Heidelberg, Germany	n.a.	Spectralis
Heidelberg Eye Explorer	Heidelberg Engineering, Heidelberg, Germany	n.a.	Version 1.9.10.0
Paraformaldehyde (PFA)	Sigma-Aldrich, Buchs, Switzerland	P5368
Phosphate buffered saline (PBS)	Sigma-Aldrich, Buchs, Switzerland	P5368
Rabbit anti-GFAP polyclonal antibody	Invitrogen, Waltham, MA, USA	180063
Silicone pin holder	Huco Vision AG Switzerland	n.a.	Cut by hand from silicone pin mat of the sterilization tray accordingly.
Slit lamp BM900	Haag-Streit AG, Koeniz, Switzerland	n.a.
Slit lamp adapter	Iridex Corp., Mountain View, CA, USA	n.a.
Superfrost Plus glass slides	Gehard Menzel GmbH, Braunschweig, Germany	10149870
TgBAC (gfap:gfap-GFP) zf167 (AB) strain	KIT, Karlsruhe, Germany	15204	http://zfin.org/ZDB-ALT-100308-3
Tris buffered saline (TBS)	Sigma-Aldrich, Buchs, Switzerland	P5912
Tween 20	Sigma-Aldrich, Buchs, Switzerland	P1379
78D non-contact slit lamp lens	Volk Optical, Mentor, OH, USA	V78C
Xylene	Sigma-Aldrich, Buchs, Switzerland	534056
Ocular fundus laser lens	Ocular Instruments, Bellevue, WA, USA	OFA2-0
2100 Retriever	Aptum Biologics Ltd., Southampton, United Kingdom	R2100-EU	Steamer