Co-Injection of Sulfotyrosine Facilitates Retinal Uptake of Hyaluronic Acid Nanospheres Following Intravitreal Injection.

Aiden Eblimit,Muayyad R Al-Ubaidi,Muna I Naash,Mustafa S Makia,Tirthankar Sinha,Daniel Strayve,Shannon M Conley,Ryan Crane,Ghanashyam Acharya

doi:10.3390/pharmaceutics13091510

Abstract

Gene and drug delivery to the retina is a critical therapeutic goal. While the majority of inherited forms of retinal degeneration affect the outer retina, specifically the photoreceptors and retinal pigment epithelium, effective targeted delivery to this region requires invasive subretinal delivery. Our goal in this work was to evaluate two innovative approaches for increasing both the persistence of delivered nanospheres and their penetration into the outer retina while using the much less invasive intravitreal delivery method. We formulated novel hyaluronic acid nanospheres (HA-NS, 250 nm and 500 nm in diameter) conjugated to fluorescent reporters and delivered them intravitreally to the adult Balb/C mouse retina. They exhibited persistence in the vitreous and along the inner limiting membrane (ILM) for up to 30 days (longest timepoint examined) but little retinal penetration. We thus evaluated the ability of the small molecule, sulfotyrosine, to disrupt the ILM, and found that 3.2 µg/µL sulfotyrosine led to significant improvement in delivery to the outer retina following intravitreal injections without causing retinal inflammation, degeneration, or loss of function. Co-delivery of sulfotyrosine and HA-NS led to robust improvements in penetration of HA-NS into the retina and accumulation along the interface between the photoreceptors and the retinal pigment epithelium. These exciting findings suggest that sulfotyrosine and HA-NS may be an effective strategy for outer retinal targeting after intravitreal injection.

Highlights

Our findings demonstrate that ST and hyaluronic acid (HA)-NS are safe for use in the retina, that HA-NS are persistent in the eye, and that co-delivery of low-dose ST dramatically increases penetration of HA-NS in the outer retina
Results at post injection (PI)-14 days using HA-NS-250 and 32 μg/μL ST (Figures 8E,F and S4C) were in between those seen with no ST and those seen with the 3.2 μg/μL ST
Similar to PI-14, at PI-30 most of the HA-NS-250 in eyes co-injected with 3.2 μg/μL ST was found in the outer retina at the retinal pigment epithelia (RPE)/outer segment interface

Summary

Introduction

The vast majority of defects underlying inherited retinal degeneration (IRD) in humans result from mutations in genes expressed in photoreceptors and the retinal pigment epithelia (RPE) [1]. Nanoscale delivery of genetic therapies to ameliorate phenotypes associated with IRD has taken many forms, including gene supplementation, knockdown, and most recently, delivery of CRISPR based approaches for gene editing (recently reviewed in [2]). While all of these approaches have been successfully employed in animal models, only one retinal gene therapy has far been FDA-approved for use in humans, an adeno-associated virus 4.0/).

Objectives

Methods

Results