Characterization of microRNAs in spent culture medium associated with human embryo quality and development

Given implantation failure limits the improvement of in vitro fertilization (IVF) success rates, there is an urgency to identify potential biomarkers for embryo quality and predict the outcomes of IVF-embryo transfer (IVF-ET).

Using RNA-sequencing, we identified the expression profiles of 16 spent culture medium (SCM) collected from embryos at the cleavage on day 3 (D3 cleavage) and blastocyst stages on day 5 (D5 blastocyst) during IVF cycles. Differentially expressed miRNAs (DEmiRNAs) were then identified, and microRNA (miRNA)-messenger RNA (mRNA) interaction networks were constructed. Finally, quantitative real-time polymerase chain reaction (qRT-PCR) confirmation and validation in the Gene Expression Omnibus (GEO) database were performed.

Compared with the pregnant group, 29 DEmiRNAs were detected in the non-pregnant group at D3 cleavage, and 26 were detected in the non-pregnant group at D5 blastocyst. Among them, a total of six known miRNAs, including hsa-miR-199a-3p>hsa-miR-199b-3p, hsa-miR-199a-5p, hsa-miR-379-5p, hsa-miR-432-5p, hsa-miR-99a-5p, and hsa-miR-483-5p, were identified. The results of Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis indicated that these target genes of DEmiRNAs were associated with various biological processes (BPs). The results of validation in qRT-PCR and the GEO database suggested the reliability of our RNA-sequencing results.

In conclusion, we identified three miRNAs, including hsa-miR-199a-5p, hsa-miR-483-5p, and hsa-miR-432-5p, which may serve as biomarkers for embryo quality during IVF cycles.