O-062 MicroRNAs in Blastocoel Fluid: a molecular signature for predicting human embryo implantation potential
Authors: Battaglia R , Caponnetto A , Ferrara C , Fazzio A , Barbagallo C , Barbagallo D , Vento M E , Carli L , Kasapi E , Palini S , Sierka W , Valerio D , Longobardi S , D’Hooghe T , Di Pietro C 
Published: June 2023

Abstract

Study question
Can microRNA expression in blastocoel fluid (BF) predict embryo implantation potential?

Summary answer
Up-regulation of miR-106, miR-373, miR-301, miR-320 and miR-525-3p represents the molecular signature characterizing the embryos with high implantation capability.

What is known already
The discovery of DNA within the BF and in spent embryo culture media, has caused increased interest in the non-invasive preimplantation testing application for monogenic disorders and aneuploidies. Aneuploid embryos have a lower implantation potential, however, chromosomal abnormalities represent only a tiny percentage of the causes of implantation failure. MiRNAs can control all cellular pathways and are involved in pluripotency, self-renewal, and stemness, and their altered regulation affects different human diseases.

Study design, size, duration
From September 2018 to March 2022, 112 BFsampleswere collected from human embryos on the fifth day of development, before the blastocyst cryopreservation. The samples were classified according to blastocyst grade and the data on implantation outcome and term births were collected for the transferred embryos. We compared the expression profiles of 89 miRNAs, previously identified in BF, between 33 BF from implanted embryos and 30 from non-implanted ones, regardless of blastocyst grade.

Participants/materials, setting, methods
By custom-designed TaqMan Low-Density Array card (TLDA), we analyzed the expression of 89 miRNAs in 4 different BF samples simultaneously. Differentially expressed (DE) miRNAs were identified by Volcano plot and Significance Analysis of Microarrays (SAM) tests. Bioinformatic analysis was performed to identify the biological role of the DE miRNAs. To evaluate miRNA’s ability for predicting implantation, Pearson’s correlation analyses, classical univariate Receiver Operator Characteristic (ROC) curve analysis, and the optimal cut-off value determination were performed.

Main results and the role of chance
We found five miRNAs, miR-106, miR-373, miR-301, miR-320 and miR-525-3pup-regulated in BF from implanted blastocysts. The identified miRNAs perform an important role during the first phases of embryo development suggesting that their up-regulation may reflect embryo health. Moreover, four of the five miRNAs showed significant correlation coefficients in both implanted and non-implanted blastocysts, indicating that their expression changes in the same way in the single sample and reflects the potentiality of the embryo to implant. Finally, ROC curve analysis confirmed that our miRNAs could be considered potential biomarkers for implantation.

Limitations, reasons for caution
Successful implantation requires a close dialogue between the embryo and the endometrium, mediated by different proteins and miRNAs produced by both the embryo and maternal tissues. Determining the quality of the embryo and its implantation potential is not sufficient to predict successful pregnancy outcomes.

Wider implications of the findings
This study represents the first report correlating miRNA profiles in BFand implantation and suggests that miRNA signature could become an accurate tool to evaluate embryo quality. It could be associated or replaced with the PGT-A to choose the most competent embryo and improve the outcome of assisted reproduction cycles.

Trial registration number
The study has been approved by theEthical Committee of Azienda Ospedaliero Universitaria Policlinico &quot;G.Rodolico -San Marco&quot; Catania.