Sorsby Fundus Dystrophy patient-derived RPE form abnormal extracellular matrices and demonstrate large basal laminar drusen

Abstract

Purpose : Previous studies have demonstrated the importance of retinal pigment epithelium (RPE) in the cellular ecosystem of the eye. Sorsby Fundus Dystrophy (SFD) is a rare disease that affects the RPE and Bruch’s membrane, resulting in central vision loss. Our aim is to determine whether SFD RPE have altered characteristics including extracellular matrix remodeling, drusen deposition, metabolism, and levels of oxidative stress compared to normal controls. We characterized the disease phenotype of iPSC-derived Sorsby Fundus Dystrophy retinal pigment epithelium.

Methods : RPE cell lines were differentiated from three distinct induced pluripotent stem cell (iPSC) clones from each of three normal control individuals and three iPSC clones each from two related individuals with SFD (S181C TIMP3 mutation). Transmission electron microscopy (TEM) and immunocytochemistry was performed on RPE cells cultured on transwell filter membranes and glass slides, respectively. Post mortem globes of affected members from the same SFD family were also examined as a comparison to the iPSC-derived SFD RPE.

Results : Unlike control RPE cells, SFD RPE cultured on transwell filter membranes elaborated a significantly thinner extracellular matrix, as detected by TEM. In contrast to control RPE, they also formed deposits that are similar in structure and composition to basal laminar drusen by TEM and immunohistochemistry. In addition, these deposits were similar in composition to the thickened Bruch’s membrane seen in post mortem SFD globes by immunohistochemistry. The basal laminar drusen demonstrated expression of multiple known drusen components including ApoE, TIMP3, and vitronectin.

Conclusions : iPSC-derived SFD RPE form an abnormal extracellular matrix with deposits similar to basal laminar drusen. The cells grown in culture create drusen deposits expressing the same markers as seen in the thickened ECM of donor globes from SFD patients.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.