Laser Induced Mouse Glaucoma Model Suitable for Studying Stem Cell-based Therapy

Abstract

Purpose: Reduced cellularity within the trabecular meshwork (TM) is observed in glaucoma patients and correlates with elevated intraocular pressure (IOP). This study aimed to develop a mouse glaucoma model with reduced TM cellularity and elevated IOP suitable for studying stem cell-based therapy for glaucoma.

Methods: The experimental glaucoma model in C57BL/6 mice was induced by photocoagulation at the limbus with cw-diode 532-nm laser once a week for 3 times. IOP was measured by Icare® TONOLAB tonometer once a week for up to 6 months. The TM structure was examined by whole mount staining and transmission electron microscopy (TEM). The structure of the anterior chamber angle was checked by optical coherence tomography (OCT) and hematoxylin and eosin (HE) staining. The function of retinal ganglion cells was evaluated by was evaluated with electroretinography (ERG) to detect Photopic negative response (PhNR). Optic nerve axons were detected by toluidine blue staining on semithin optic nerve sections. The ability of TM stem cells to home to laser damaged TM region and repair the tissue was confirmed by whole mount staining and TEM.

Results: Ninety percent of mice received limbal laser photocoagulation manifest IOP above 20 mmHg for up to 6 months; IOP elevated from 14.3 ± 1.97 mmHg to 27.9±6.93 mmHg. Whole mount staining showed lower TM cellularity in experimental glaucoma eyes. TEM images indicated swollen and degenerating mitochondria and endoplasmic reticulum in TM cells and endothelial cells of Schlemm’s canal. OCT and HE staining showed that the anterior chamber angle was still visible after laser photocoagulation. ERG detected reduced or absent PhNR in the experimental glaucoma eyes. Toluidine blue staining showed shrunken and swollen axons in glaucomatous eyes. After injected into laser damaged mouse anterior chamber, TM stem cells were able to home to the damaged TM tissue and partially repair the damaged TM structure.

Conclusions: This laser-induced mouse model was similar to the human open angle glaucoma phenotype, and may be an appropriate model for studying stem cell treatment for glaucoma to restore TM structure and function.

Keywords: 735 trabecular meshwork • 568 intraocular pressure • 721 stem cells