In this study, for the first time, we demonstrated the presence of microRNAs and extracellular vesicles in human blastocoel fluid. The bioinformatic and comparative analyses identified the biological function of blastocoel fluid microRNAs and suggested a potential role inside the human blastocyst. We found 89 microRNAs, expressed at different levels, able to regulate critical signaling pathways controlling embryo development, such as pluripotency, cell reprogramming, epigenetic modifications, intercellular communication, cell adhesion and cell fate. Blastocoel fluid microRNAs reflect the miRNome of embryonic cells and their presence, associated with the discovery of extracellular vesicles, inside blastocoel fluid, strongly suggests their important role in mediating cell communication among blastocyst cells. Their characterization is important to better understand the earliest stages of embryogenesis and the complex circuits regulating pluripotency. Moreover, blastocoel fluid microRNA profiles could be influenced by blastocyst quality, therefore, microRNAs might be used to assess embryo potential in IVF cycles.
The aim of this pilot study was to assess if array comparative genomic hybridization (aCGH), non-invasive preimplantation genetic screening (PGS) on blastocyst culture media is feasible. Therefore, aCGH analysis was carried out on 22 spent blastocyst culture media samples after polar body PGS because of advanced maternal age. All oocytes were fertilized by intracytoplasmic sperm injection and all embryos underwent assisted hatching. Concordance of polar body analysis and culture media genetic results was assessed. Thirteen out of 18 samples (72.2%) revealed general concordance of ploidy status (euploid or aneuploid). At least one chromosomal aberration was found concordant in 10 out of 15 embryos found to be aneuploid by both polar body and culture media analysis. Overall, 17 out of 35 (48.6%) single chromosomal aneuploidies were concordant between the culture media and polar body analysis. By analysing negative controls (oocytes with fertilization failure), notable maternal contamination was observed. Therefore, non-invasive PGS could serve as a second matrix after polar body or cleavage stage PGS; however, in euploid results, maternal contamination needs to be considered and results interpreted with caution.
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