Extracellular Vesicles, From Pathogenesis to Therapeutics in Retinal Degenerations

Abstract

Age-related macular degeneration (AMD) is a complex retinal disease that leads to degeneration of the central retina, resulting in irreversible vision loss. The onset and progression of AMD is driven by a combination of genetic, lifestyle, and environmental factors that contribute to oxidative stress and chronic inflammation, two hallmark features of AMD. Its multifactorial nature, combined with the immune-privileged environment in which the retina resides, makes AMD particularly challenging to treat. Currently, for dry AMD, which accounts for 90% of cases, there are only two FDA-approved drugs. However, both drugs target single or limited pathways in the late stages of the disease, reducing lesion size without slowing vision loss. They also require invasive ocular administration by a clinician, making them less accessible and posing risks associated with repeated dosing. This highlights the need for new treatment strategies that address both the complexity of AMD and the challenge of treating inflammation within the retina. This thesis will explore how extracellular vesicles (EVs), which act as intercellular delivery vehicles, contribute to the development of AMD and investigate their potential as therapeutics to target chronic inflammation and slow vision loss.

In this thesis, I investigate the role of EVs in mediating retinal inflammation during pyroptosis, a form of inflammatory cell death, in both healthy and degenerating states of the retina. The results from this study show that EVs contribute to inflammation by packaging and releasing proinflammatory cytokine IL-1beta. Additionally, mice with reduced pyroptosis capability demonstrated better preserved retinal function, increased photoreceptor survivability and reduced inflammation. This work provides key insights into how the retina may regulate inflammation through EV release, suggesting that targeting pyroptosis or EV release with pharmacological or RNA-based inhibitors could offer therapeutic benefits for retinal degeneration such as AMD.

This thesis also explores EVs, which can cross blood tissue barriers and modulate a range of biological pathways, as a novel therapeutic strategy for AMD. In this work, we use a low-immunogenic EV source, red blood cells (RBCs) to develop a novel incubation pipeline to obtain reproducible, homogenous, and anti-inflammatory EV populations. The RBC EVs generated in this study were neuroprotective, effectively reducing inflammation and cell death, and slowing vision loss in a murine model of AMD. Additional analysis revealed that these RBC EVs possess an anti-inflammatory profile, further validated by their ability to modulate proinflammatory cytokine output in peripheral blood mononuclear cells (PBMCs). Together, these findings support the use of RBC EVs as a promising therapeutic strategy for retinal degeneration, contributing to a patent application currently in examination.

Finally, this thesis tackles the clinical challenges of using EVs as therapeutics by exploring EV loading, benchmarking new EV products against commercial alternatives, and translating pre-clinical findings to human applications. This thesis demonstrates how the incubation pipeline for murine RBCs can be adapted to human RBCs and optimize therapeutic RNA loading for retinal degeneration treatment.

Overall, this thesis highlights the dual role of EVs- both in disease progression and as a promising therapeutic strategy for retinal degenerations including AMD. Show more