Exploring the Impact of Extracellular Vesicles in Proliferative Diabetic Retinopathy: Insights from Vitreous Profiling

Abstract

Purpose : Diabetic retinopathy (DR) is a complex retinal disorder, involving various cell types. Consequently, gaining a profound understanding of disease-related cellular and molecular modifications within the retina and vitreous is crucial for developing future preventive and therapeutic strategies. Extracellular vesicles (EVs) have emerged as a focal point in research due to their role as intercellular communication platform, facilitating cargo delivery from donor to recipient cells. This project aimed to compare the EV profile in the human vitreous of patients with and without proliferative DR (PDR), to enhance our understanding of the complex pathophysiology of DR.

Methods : Undiluted human vitreous and blood samples were collected at the beginning of vitrectomies from three distinct patient groups: 1. PDR with vitreous hemorrhage, 2. PDR without vitreous hemorrhage, 3. Control (macular pucker). To analyze the EV profile, large and small EVs were isolated by tangential flow filtration and size exclusion chromatography. Characterization of the EV subpopulations involved assessing particle and total protein concentrations through nanoparticle tracking analysis (NTA) and MicroBCA, complemented by transmission electron microscopy (TEM). Lastly, EV-specific biomarker concentrations (e.g. CD9, CD63 and CD81) were compared using MSD assays.

Results : Particle characterization through NTA, TEM and EV-specific biomarker analysis revealed significantly higher levels of small EVs in the vitreous of PDR patients compared to controls, where particle and biomarker concentrations often laid below the lower detection limit. Comparison of diabetic patients with and without vitreous hemorrhage revealed similar particle concentrations in both groups with particularly high inter-sample variability in particle and biomarker concentrations in vitreous samples with hemorrhage. Interestingly, comparison of blood samples showed no significant differences between groups, while overall particle concentration as well as inter-sample variability was higher in all groups.

Conclusions : Our findings suggest a potential role of EVs in the complex pathophysiology of DR, as increased EV levels were only identified in vitreous but not blood samples from PDR patients. Further investigations addressing the origin and function of vitreous EVs are essential for obtaining a comprehensive understanding of the disease.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.