Abstract
Purpose :
Primary open angle glaucoma (POAG) is the most common type of glaucoma. Elevated intraocular pressure (IOP) is a major risk factor in POAG. In order to model POAG, we induced chronic IOP elevation in mice by injecting a UVA-sensitive biomatrix into the anterior chamber as previously described by Guo et al. (PMID: 29949582)
Methods :
IOP was increased in C57BL/6 mice by intracamerally injecting 2µL of hyaluronic acid glycidyl methacrylate (HAMA, 2.3–2.5%) and lithium phenyl-2,3,6-trimethylbenzoylphosphinate (0.1%) (henceforth referred to as "HAMA mix"). An UVA (635nm) generator with irradiance of ~250mW/cm2 was used to polymerize the mix by exposing eyes for 10–20s at a distance of 10cm. Unpolymerized HAMA or PBS was bilaterally injected as controls. In some animals an AAV2 vector regulating the expression of CNTF, shPTEN or GFP was intravitreally administered 2 weeks before HAMA mix injection. IOP was routinely measured in all mice during the course of the experiments. Retinas were collected terminally for RGC quantitation by immunostaining of flatmounts and for gene expression by qPCR. Data were also collected to check morphological and functional changes by fundus imaging, OCT, and pSTR (positive scotopic threshold response) ERG
Results :
IOP was elevated by 10-15 mmHg 2–3 days after injection of HAMA mix and was maintained ≥25% above baseline for at least 4 weeks. At week 4, we found ~48% RGC loss by Brn3a staining in AAV2-GFP+HAMA mix-injected mice compared to intact mice, with >10% ganglion cell complex (GCC) reduction by OCT and >50% reduction in pSTR amplitude. No significant differences from intact mice were observed in the eyes of PBS- or unpolymerized HAMA-injected mice. Administration of AAV2-CNTF did not ameliorate IOP elevation but preserved RGCs (~28% loss at 4 weeks vs 48% in the AAV-GFP group). qPCR analysis indicated reduced expression of RGC markers (Brn3a and RBPMS) and upregulation of inflammation-associated genes (TNF-a and CD11b) after IOP elevation
Conclusions :
Robust and sustained intraocular hypertension can be induced by intracameral injection of HAMA mix. We observed that IOP elevation caused GCC reduction that correlated with the RGC loss and associated functional decline in the model. CNTF expression, but not shPTEN expression, by AAV2 spared RGCs after IOP elevation
This is a 2020 ARVO Annual Meeting abstract.