Comparison of Fibroblasts and RPE Cells for Their Ability to Induce PVR in Rabbits

Abstract

Purpose:: In the rabbit model of proliferative vitreoretinopathy (PVR), fibroblasts robustly induce the disease, and they must be able to respond to platelet-derived growth factor (PDGF) in order to do so. Retinal pigment epithelial cells (RPEs) are particularly abundant in epiretinal membranes isolated from donor patients, and hence also a relevant cell type to be used in the rabbit model. The purpose of this study was to compare PVR that develops when rabbits are injected with either fibroblasts or RPE cells.

Methods:: The cell types used were primary rabbit conjunctival fibroblasts (RCF) or human ARPE19 cells stably expressing the PDGF α receptor (RPE-α). PVR was induced in the right eye of 20 pigmented rabbits by injecting 2 x 10⁵ or 3 x 10⁵ cells suspended in 0.1cc of serum free DMEM, in conjunction with 0.1 cc of platelet rich plasma. A gas vitrectomy (0.1cc of 100% C3F8) was performed 7 days prior to the injection of cells. Fourteen rabbits were injected with 2.5 x 10⁵ RCFs, and 6 with RPEα cells (3 with 2 x 10⁵ cells and 3 with 3 x 10⁵ cells). Rabbits were examined by a single investigator on days 1, 5, 7, 14, 21, and 28 via indirect ophthalmoscopy. PVR was graded using the Fastenberg classification as follows: 0, no abnormality; 1, vitreous strands; 2, traction of the retina; 3, retinal detachment (RD) involving less than two quadrants; 4, RD including more than two quadrants; 5, total RD.

Results:: Large intravitreal cell clusters were confirmed in all injected eyes on day 1. On day 7, all rabbits injected with RCFs had advanced PVR (stage 3-4). By day 14, all eyes injected with RCFs had advanced to stage 5. The disease developed differently in eyes injected with RPEα cells. The injected cells remained clumped and the vitreous was clear for the first 14 days. Fibrosis and haze developed thereafter, and by day 28 retinal detachment (stage 3 or greater) was observed in all eyes.

Conclusions:: Both fibroblasts and RPEα cells induce PVR, and the kinetics and nature of disease progression is quite different. Importantly, RPEα cells induce disease that more closely resembles PVR in humans. These modifications to the rabbit model increase its utility to study the pathogenesis of as well as possible treatment measures for PVR.

Keywords: proliferative vitreoretinopathy • retinal pigment epithelium • receptors