Decorin^-/- Depicts Structural and Vascular Abnormalities in Adult Mouse Retina

Abstract

Purpose : Decorin (Dcn) is a chondroitin/dermatan sulfate proteoglycan associated with cell proliferation and extracellular matrix assembly in the eye. A previous study has suggested its role in differentiation of retinal ganglion cells during development and neuronal repair after injury. The present study aims to investigate the functional role of Dcn in the adult mouse retina.

Methods : Eight-twelve weeks old C57Bl/6J and Dcn knockout (Dcn^-/-) mice were used in the study. Fundus photography and fluorescein fundus angiography (FFA) were performed using Micron IV. Lectin staining in retinal flat mounts and trypsin digests were made for the identification of vascular abnormalities. Retinal sections (8-10 mm) were used immunostaining for retinal cell markers. Retinal lysates were prepared for gene and protein profiling of angiogenic and inflammatory factors. Retinal cellular and structural abnormalities were observed using electron microscopy.

Results : Dcn^-/- retina histology showed disrupted cellular architecture and overall reduction in retinal thickness. Fundus and FFA imaging of Dcn^-/- retina showed reduced caliber (thickness) with increased tortuosity (curvature) and fractal dimensions (hyperbranching). Retinal trypsin digest of Dcn^-/- indicated thinner capillaries with flattened endothelial cells and acellular capillaries. EM indicated severe cell loss and structural deformities. Dcn^-/- mice retina showed increased expression of angiogenic and inflammatory factors. Immunostaining of retinal cell markers depicted loss of vascular integrity as seen by elevated expression of Collagen IV in the ganglion cell layer (GCL) and choroid. Increased VEGF production in Dcn^-/- mice was further accompanied by activation of glutamine synthetase (GS, Muller cell marker) and CRALBP (Muller and RPE cell marker) staining.

Conclusions : This is the first study to characterize the functional role of Decorin in the maintenance of retinal structural integrity and vasculature.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.