Aqueous humor (AH) is a dynamic intraocular fluid that supports the vitality of tissues that regulate intraocular pressure. Researchers at Duke University Medical Center recently discovered that extracellular nanovesicles called exosomes are a major constituent of AH. Exosomes function in extracellular communication and contain proteins and small RNA. Our goal was to characterize the physical properties of AH exosomes and their exosomal RNA (esRNA) content. The researchers isolated exosomes from human AH collected during cataract surgery from five patients using serial ultracentrifugation. They measured the size and concentration of AH exosomes in solution using nanoparticle tracking analysis and found a single population of vesicles having a mean size of 121 ± 11 nm in the unprocessed AH. They extracted esRNA from the pooled human AH samples and generated a sequencing library for small RNA sequencing. More than 10 different miRNAs were identified; abundant species included miR-486-5p, miR-204, and miR-184. The researchers found that the majority of extracellular vesicles in the AH were in the exosome size range, suggesting that miRNAs housed within exosomes may function in communication between AH inflow and outflow tissues.
Exosomes are a major constituent of aqueous humor fluid
Dismuke WM, Challa P, Navarro I, Stamer WD, Liu Y. (2015) Human aqueous humor exosomes. Exp Eye Res [Epub ahead of print]. [abstract]