Abstract
Purpose :
The vitreous is an information-rich matrix and serves as a proximal biofluid of the retina. We recently described an abundant population of extracellular vesicles (EVs) in vitreous from humans with no retinal vascular disease. The purpose of this study was to determine if EV concentration and/or size distribution is altered in patients with retinal disease.
Methods :
Vitreous was acquired from patients with proliferative diabetic retinopathy (PDR; n=5), diabetic macular edema (DME; n=5), and age-related macular degeneration (AMD; n=6). PDR vitreous was obtained during vitrectomy for non-clearing vitreous hemorrhage. DME vitreous was obtained in clinic before and after intravitreal anti-vascular endothelial growth factor treatment. AMD vitreous was acquired in clinic from treatment-naïve patients with exudative AMD. Control vitreous was derived from patients undergoing repair of macular hole or epiretinal membrane (MH/ERM; n=6). Unfractionated samples were analyzed by NanoSight (Malvern) nanoparticle tracking analysis for quantification and characterization of vitreous EV populations. Protein concentration was determined by DC Protein Assay (Bio-Rad). This study was approved by the University of Michigan and Penn State College of Medicine institutional review boards and adhered to the tenets of the Declaration of Helsinki. Statistical analysis was by t-test.
Results :
Mean and mode particle diameter were similar across samples and ranged from 154-195 nm and 112-134 nm, respectively. PDR vitreous had significantly higher average EV concentration than controls (57 x 109particles/mL PDR, 25 x 109particles/mL MH/ERM; p<0.05). PDR (p<0.5), pre- and post-treatment DME (p<0.01 and p<0.001, respectively), and AMD (p<0.001) samples had lower protein concentrations than MH/ERM vitreous.
Conclusions :
These novel data demonstrate that EVs are a major constituent of vitreous in multiple retinal diseases. EV concentration in PDR vitreous was approximately twice that of controls, while MH/ERM vitreous had the highest protein concentration.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.