SRA

Improving embryo implantation rates has become one of the greatest challenges in assisted reproduction techniques. Implantation process requires a synchrony between the development of the embryo and the endometrium, but also, an adequate embryo-endometrial crosstalk. MicroRNAs (miRNAs) and extracellular vesicles (EVs) from endometrial fluid (EF) have been described to be mediators of this communication. Therefore, the molecular analysis of the miRNA content of EF could provide a non-invasive method to recognize an implantative endometrium and consequently improve the implantation rates. In this work, we optimized EF sample collection procedure and performed a comparative analysis of five different methodologies to enrich miRNA content of EF with the purpose of identifying a simple, sensitive, reproducible and non-invasive method that allow the quick identification of an implantative endometrium. Then, we applied the selected methodology in a set of real samples with different implantation outcome. Our results showed that EVs enrichment protocols permit to detect a higher number of miRNAs. In addition, we obtained two predictive models based on three miRNAs that allow us to differentiate between an implantative and non-implantative endometrium. Model 1 (Area under the curve (AUC)=0.93; p-value=0.0033): hsa-miR-200b-3p, hsa-miR-24-3p and hsa-miR-148b-3p. Model 2 (AUC=0.92; p-value=0.0002): hsa-miR-200b-3p, hsa-miR-24-3p and hsa-miR-99b-5p. This work supports the feasibility to analyze EVs and EVs-associated miRNAs from a small volume of EF sample and the development of EV-miRNAs based assays as low-invasive tools for the detection of an implantative endometrium. Overall design: Comparison of methods for the characterization of miRNAs from 400uL (1:30 dilution) of endometrial fluid