MicroRNA expression in the human blastocyst

Objective To determine the most highly expressed microRNAs (miRNAs) in human blastocysts and to compare miRNAs in euploid versus aneuploid embryos and in male versus female embryos. Design Experimental study of human embryos: 14 blastocysts (four male, five female, and five aneuploid) were evaluated for miRNA expression with the use of an array-based quantitative real-time polymerase chain reaction (qPCR). Highly expressed and differentially expressed miRNAs were confirmed with the use of qPCR in an expanded set of 27 blastocysts (seven male, eleven female, and nine aneuploid). Setting Academic IVF program. Patient(s) Thirteen couples donated 91 cryopreserved embryos for this study. Intervention(s) None. Main Outcome Measure(s) Relative miRNA expression in individual blastocysts. Result(s) The most highly expressed miRNA in euploid embryos was miR-372. Many of the highly expressed miRNAs have been shown to be critical to mammalian embryo development and to maintenance of stem cell pluripotency. Several differentially expressed miRNAs were discovered based on chromosomal makeup, including sex of the embryo. Conclusion(s) Human blastocysts express miRNAs, which may be important to their survival. Differential miRNA expression based on sex implies some degree of differentiation at the blastocyst stage of development. Differential miRNA expression between euploid and aneuploid embryos may be an early indicator of their prognosis or a mechanism behind their eventual fate.