A potential novel therapy for PVR: HC-HA/PTX3, an active matrix component of amniotic membrane, inhibits proliferation of rabbit RPE cells and is non-toxic intravitreally

Abstract

Purpose : Proliferative vitreoretinopathy (PVR), characterized by retinal surface membranes, is the main cause of failure of rhegmatogenous retinal detachments (RRDs). PVR is mediated by proliferation and epithelial mesenchymal transition (EMT) of RPE cells under the influence of vitreous growth factors. Heavy chain-hyaluronic acid/pentraxin 3 (HC-HA/PTX3) complex is a unique matrix component from amniotic membrane that exerts anti-inflammatory and anti-EMT effects. We previously demonstrated that HC-HA/PTX3 inhibits ARPE-19 proliferation and EMT in vitro. HC-HA/PTX3 can be solubilized and injected intravitreally. Therefore, we investigated whether HC-HA/PTX3 inhibits rabbit RPE cell proliferation in vitro, evaluated the safety of intravitreal HC-HA/PTX3, and established a rabbit PVR model for future studies.

Methods : We first tested if 12.5 to 200 µg/ml HC-HA/PTX3 was toxic to rabbit RPE cells in comparison to HA by the WST-1 assay. Next, we assessed the inhibitory effect of HC-HA/PTX3 on epidermal growth factor (EGF) and fibroblast growth factor (FGF)-induced proliferation in vitro by the WST-1 assay. We tested the safety of intravitreal HC-HA/PTX3 injections using weekly ERGs and fundus exams for four weeks, followed by histologic analysis. Additionally, we established a model of PVR in New Zealand white (NZW) rabbits using gas displacement of vitreous with intravitreal C₃F₈ and intravitreal injection of NZW RPE cells to induce PVR in four rabbits.

Results : There was no difference in rabbit RPE cell viability by addition of HA-HA/PTX3 or HA. EGF+FGF induced a 2-fold increase (p<0.05) in proliferation. Addition of 12.5 - 200 µg/ml HC-HA/PTX3 inhibited EGF+FGF-induced proliferation in a dose-dependent fashion, up to 2.2-fold (p<0.05), while addition of HA along did not. Two rabbits injected with intravitreal HC-HA/PTX3 did not demonstrate any ERG or fundus exam changes and did not develop any histologic changes. Using the model of PVR, all rabbits developed Stage III of higher PVR.

Conclusions : HC-HA/PTX3 is a non-toxic, potent inhibitor of RPE cell proliferation and EMT in vitro. We will further test whether intravitreal injection of HC-HA/PTX3 can inhibit PVR formation using the established rabbit model of PVR.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.