CD44 aptamer mediated cargo delivery to lysosomes of retinal pigment epithelial cells to prevent age-related macular degeneration

Chetan Chandola,Marco G Casteleijn,Urvashi M Chandola,Lakshmi Narayanan Gopalan,Arto Urtti,Muniasamy Neerathilingam

doi:10.1016/j.bbrep.2019.100642

Abstract

Age related macular degeneration (AMD) is a progressive, neurodegenerative disorder that leads to the severe loss of central vision in elderlies. The health of retinal pigment epithelial (RPE) cells is critical for the onset of AMD. Chronic oxidative stress along with loss of lysosomal activity is a major cause for RPE cell death during AMD. Hence, development of a molecule for targeted lysosomal delivery of therapeutic protein/drugs in RPE cells is important to prevent RPE cell death during AMD. Using human RPE cell line (ARPE-19 cells) as a study model, we confirmed that hydrogen peroxide (H2O2) induced oxidative stress results in CD44 cell surface receptor overexpression in RPE cells; hence, an important target for specific delivery to RPE cells during oxidative stress. We also demonstrate that the known nucleic acid CD44 aptamer - conjugated with a fluorescent probe (FITC) - is delivered into the lysosomes of CD44 expressing ARPE-19 cells. Hence, as a proof of concept, we demonstrate that CD44 aptamer may be used for lysosomal delivery of cargo to RPE cells under oxidative stress, similar to AMD condition. Since oxidative stress may induce wet and dry AMD, both, along with proliferative vitreoretinopathy, CD44 aptamer may be applicable as a carrier for targeted lysosomal delivery of therapeutic cargoes in ocular diseases showing oxidative stress in RPE cells.

Highlights

Age related macular degeneration (AMD) is a progressive, neurodegenerative disorder that leads to the loss of central vision in elderly people [1]
AMD is classified to two forms: the wet form involves choroidal neovascularization (CNV), and the dry form is associated with geographic atrophy (GA)
CD44 surface receptor is a well-known biomarker for certain cancers and cancer stem cells, its expression pattern has not been studied in the retinal pigment epithelium (RPE) cells under oxidative stress, which is an important factor in the development of AMD

Summary

Introduction

Age related macular degeneration (AMD) is a progressive, neurodegenerative disorder that leads to the loss of central vision in elderly people [1]. Though AMD is a multifactorial disorder, the most common reason for dry AMD is oxidative stress whereas the wet form is mainly caused by inflammation, which may itself be induced by oxidative stress [1]. This oxidative stress is generated in RPE cells due to substantial consumption of oxygen, accumulation of lipid peroxidation products from ingested photoreceptor outer segments, and constant exposure to light. Clinical studies have shown that dry AMD may develop into wet AMD, it is important to develop therapeutic interventions at the early stage of dry AMD to avoid progression to the more aggressive wet form of the disease

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