Human embryos secrete microRNAs into culture media--a potential biomarker for implantation.

Objective: To determine whether human blastocysts secrete microRNA (miRNAs) into culture media and whether these reflect embryonic ploidy status and can predict in vitro fertilization (IVF) outcomes.

Design: Experimental study of human embryos and IVF culture media.

Setting: Academic IVF program.

Patient(s): 91 donated, cryopreserved embryos that developed into 28 tested blastocysts, from 13 couples who had previously completed IVF cycles.

Intervention(s): None.

Main Outcome Measure(s): Relative miRNA expression in IVF culture media.

Result(s): Blastocysts were assessed by chromosomal comparative genomic hybridization analysis, and the culture media from 55 single-embryo transfer cycles was tested for miRNA expression using an array-based quantitative real-time polymerase chain reaction analysis. The expression of the identified miRNA was correlated with pregnancy outcomes. Ten miRNA were identified in the culture media; two were specific to spent media (miR-191 and miR-372), and one was only present in media before the embryos had been cultured (miR-645). MicroRNA-191 was more highly concentrated in media from aneuploid embryos, and miR-191, miR-372, and miR-645 were more highly concentrated in media from failed IVF/non-intracytoplasmic sperm injection cycles. Additionally, miRNA were found to be more highly concentrated in ICSI and day-5 media samples when compared with regularly inseminated and day-4 samples, respectively.

Conclusion(s): MicroRNA can be detected in IVF culture media. Some of these miRNA are differentially expressed according to the fertilization method, chromosomal status, and pregnancy outcome, which makes them potential biomarkers for predicting IVF success.