Pluripotency and cellular differentiation miRNAs expressed in human blastocoel fluid are associated with embryo quality

Abstract Purpose To analyse the microRNAs (miRNAs) present in blastocoel fluid (BF) and assess the relationship with blastocyst quality. Methods Seventy-two blastocysts from 57 women (25 IVF patients and 32 oocyte donors) undergoing IVF in a single private Fertility Center were included. Blastocyst quality was evaluated using Gardner´s classification. BF was collected prior to cryopreservation. MiRNA sequencing (miRNA-Seq) was employed to analyse pooled blastocoel fluid from 8 good-quality (GQ) and 8 medium/poor-quality embryos (PQ). Differential expression of miRNAs was validated in individual BF by relative quantitative real-time PCR (qRT-PCR) in 18 good-quality and 38 medium/poor-quality embryos. Target genes were identified using in silico prediction algorithms. Results Using miRNA-seq we identified 85 mature and 75 immature miRNAs and selected 16 miRNAs differentially expressed in GQ and PQ embryos, with a read count exceeding 10. At the p < 0.05 level, eight miRNAs were upregulated in GQ compared to PQ embryos (miR-7107-5p, miR-4687-3p, miR-6743-5p, miR-4651, miR-6503, miR-4516, miR-4472.2, miR-409) and 8 were upregulated in PQ compared to GQ embryos (miR-6805-3p, miR-663a, miR-4438, miR-6068, miR-1182, miR-2682, miR-1908, miR-4754). In individual BF, qRT-PCR identified significantly lower expression of miR-663a, miR-7107-5p and miR-4687-3p in GQ embryos. Hatched GQ embryos had lower expression of miR-6805-3p, miR-663a and miR-4651 compared to unhatched GQ embryos. In silico predicted target genes were associated with cellular growth and differentiation, apoptosis, pluripotency, and embryonic development. Conclusion Specific expression profiles of BF microRNAs involved in pluripotency and cellular differentiation may be associated with blastocyst quality and hatching and represent potential biomarkers for successful embryo transfer.