Expression of pigment epithelium-derived factor and thrombospondin-1 regulate proliferation and migration of retinal pigment epithelial cells.

Mitra Farnoodian,Ismail Zaitoun,Christine M Sorenson,Saeed Yadranji Aghdam,James B Kinter,Nader Sheibani

doi:10.14814/phy2.12266

Abstract

Age‐related macular degeneration (AMD) is the leading cause of vision loss among elderly. Although the pathogenesis of AMD is associated with retinal pigmented epithelium (RPE) dysfunction and abnormal neovascularization the detailed mechanisms remain unresolved. RPE is a specialized monolayer of epithelial cells with important functions in ocular homeostasis. Pathological RPE damage contributes to major ocular conditions including retinal degeneration and irreversible loss of vision in AMD. RPE cells also assist in the maintenance of the ocular angiogenic balance by production of positive and negative regulatory factors including vascular endothelial growth factor (VEGF), thrombospondin‐1 (TSP1), and pigment epithelium‐derived factor (PEDF). The altered production of PEDF and TSP1, as endogenous inhibitors of angiogenesis and inflammation, by RPE cells have been linked to pathogenesis of AMD and choroidal and retinal neovascularization. However, lack of simple methods for isolation and culture of mouse RPE cells has resulted in limited knowledge regarding the cell autonomous role of TSP1 and PEDF in RPE cell function. Here, we describe a method for routine isolation and propagation of RPE cells from wild‐type, TSP1, and PEDF‐deficient mice, and have investigated their impact on RPE cell function. We showed that expression of TSP1 and PEDF significantly impacted RPE cell proliferation, migration, adhesion, oxidative state, and phagocytic activity with minimal effect on their basal rate of apoptosis. Together, our results indicated that the expression of PEDF and TSP1 by RPE cells play crucial roles not only in regulation of ocular vascular homeostasis but also have significant impact on their cellular function.

Highlights

Age-related macular degeneration (AMD) is one of the major causes of visual impairment in the elderly population worldwide
AMD is presented in two major forms, the dry form which is associated with degeneration of retinal pigment epithelium (RPE), and the exudative or wet form which presents the formation of choroidal neovascularization (CNV) (Hua et al 2012).The impairment of RPE cell function is an early and crucial event in the molecular pathways leading to clinically relevant AMD changes associated with increased production of vascular endothelial growth factor (VEGF) and CNV
The PEDFÀ/À RPE cells exhibited a more spindle-shaped and elongated morphology compared to wild-type cells on gelatin-coated plates, while TSP1À/À RPE cells exhibited a similar morphology as wild-type RPE cells (Fig. 1B)

Summary

Introduction

Age-related macular degeneration (AMD) is one of the major causes of visual impairment in the elderly population worldwide. AMD is presented in two major forms, the dry form which is associated with degeneration of retinal pigment epithelium (RPE), and the exudative or wet form which presents the formation of choroidal neovascularization (CNV) (Hua et al 2012).The impairment of RPE cell function is an early and crucial event in the molecular pathways leading to clinically relevant AMD changes associated with increased production of vascular endothelial growth factor (VEGF) and CNV. The detailed mechanisms impacting RPE cell function and pathogenesis of AMD remain poorly defined. The failure of RPE cell function results in major ocular clinical changes such as retinal degeneration and irreversible vision loss (Korte et al 1984; Yang et al 2006a,b)

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