Extracellular vesicles microRNA cargo in porcine follicular fluids: the potential association with oocyte quality

The objective of this study was to identify miRNA expression profiles of extracellular vesicles (EVs) from porcine follicular fluids (FFs) in association with oocyte quality. Antral follicles were aspirated individually and oocytes were stained with 0.5% Lissamine Green B stain (LB), a vital stain for oocyte quality. Each oocyte was classified separately according to the stain into high-quality (unstained; HQ) and low-quality (stained; LQ). Oocyte corresponding FFs were pooled together into HQ and LQ groups and their EV-miRNAs were isolated and sequenced. Sequencing analysis revealed that a total of 295 known miRNAs were commonly detected in both groups. MiR-27b-3p, miR-140-3p, miR-29a-3p, miR-202-5p, and miR-16 were the top highly abundant miRNAs in both groups. Differentially expression (DE) analysis exhibited that 19 miRNAs (including miR-193a-5p, miR-125b, and miR-320) were up- while 22 (including miR-9, miR-6516, and miR-206) were down-regulated in the HQ compared to the LQ group. Overall design: Six small-RNA libraries were prepared from two different groups of follicular fluid-extracellular vesicles (FF-Evs) corresponding to oocyte quality (High vs. Low) and sequenced on an Illumina NovaSeq 6000.