Target gene repression mediated by miR-144 and miR-224 in cumulus cells is related to the success of oocyte maturation and fertilisation in patients with polycystic ovary syndrome (PCOS).

Context: In vitro maturation (IVM) of oocytes is an alternative approach for patients with polycystic ovary syndrome (PCOS) predisposing to ovarian hyperstimulation syndrome (OHSS). Transcriptomic analysis of cumulus cells (CC) may help make IVM more efficient. The aim of this study was to examine the impact of miR-144 and miR-224 and their candidate target genes (COX-2 and PTX-3 , respectively) expression on oocyte development in PCOS patients.

Methods: Immature oocytes were retrieved from 20 PCOS patients. After IVM, samples were divided into two groups: matured (M) and immatured (I) oocytes. ICSI was performed and the embryo quality was evaluated. qPCR was used to analyse miR-144, miR-224, COX-2 and PTX-3 expression levels in CCs of each group.

Key Results: We found that the expression levels of miR-144 and miR-224 were lower and the COX-2 and PTX-3 mRNA levels were higher in CCs of M group than in CCs of I group. The expression level of miR-144 and miR-224 in unfertilised oocytes were higher than fertilised oocytes. The contrary results were observed for COX-2 and PTX-3 . A reduction pattern in the expression level of miR-144 and miR-224 and increasing pattern in the level of COX-2 and PTX-3 expression were observed in high quality compared to low quality embryos.

Conclusions: The selected miRNAs were related to oocyte maturation, fertilisation and embryo development. These results support their critical involvement in oocyte development.

Implications: Our findings may help reveal the mechanisms of post-transcriptional regulation by miR-144 and miR-224 during IVM procedure.