Urinary Exosomal RNA Isolation and Quantification

Mid-stream, second morning void urine samples were collected, centrifuged at 2,000× g for 20 minutes at room temperature, and the supernatant was transferred into RNA later solution (Thermo Scientific, Waltham, MA) and stored at -80°C until further use. Urinary exosomal RNA was isolated from 1 mL of urinary supernatant using spin column-based exoRNeasy serum/plasma midi kits (QIAGEN GmbH, Hilden, Germany), as described previously (11 (link)). The quantity (absorbance at 260 nm) and purity (ratio of absorbance at 260 and 280 nm) of RNA were measured using NanoDrop1 ND-2000 UV spectrophotometer (Thermo Scientific).