Serum is preferable to plasma for circulating exosomal microRNA biomarker discovery studies

Exosomes were purified from 250 ul matched plasma and serum samples using ExoQuickTm. The presence of particles consistent in size with exosomes (60-150nm) was confirmed using a Nanosight LM10. miRNA was extracted from exosomes using an miRNeasy Serum/Plasma kit (Qiagen, #217184). miRNA was reversed transcribed using a TaqMan® microRNA Reverse Transcription Kit (Life technologies, #4366596). miRNA profiling was performed with a high throughput TaqMan® OpenArray® Human microRNA panel (Life technologies, #4461104). The panel consisted of probes for 754 human miRNAs that are based on miRNA sequences derived from Sanger miRBase v14. MegaplexTM Primer Human Pool A v2.1 and Human Pool B v2.0 or v3.0 OpenArray high throughput real time PCR of microRNAs purified from exosomes that were isolated from matched serum and plasma samples from 10 patients without oesophageal disease, and 10 patients with locally advanced Oesophageal Adenocarcinoma.