JBRA Assisted Reproduction 2025;29(Suppl.2 SBRA 2025):250
Poster Presentation
29^th Annual Congress of the SBRA. São Paulo/SP - Brazil, 2025
doi: 10.5935/1518-0557.20263831

P-238. Transcriptional profiling of extracellular vesicles in uterine fluid as a non-invasive tool for assessing endometrial receptivity in IVF patients

Claudia Ferraro¹, Arianna Nani¹, Roberta Bellinghieri¹, Laura Sichenze¹, Elisa Giacomini², Valentina Pavone², Marco Reschini¹, Vittoria Sterpi¹, Maira Casalechi¹, Paola Vigano¹

¹ Fondazione IRCCS CA' Granda Ospedale Maggiore Policlinico - Milano - Italy
² IRCCS Ospedale San Raffaele - Italy

Objective: In in vitro fertilization (IVF) treatments, a key determinant of successful embryo implantation is the receptive state of the endometrium on the day of embryo transfer (ET). Current clinical methods for assessing endometrial receptivity are based on algorithms derived from gene expression profiles obtained through endometrial biopsy, an invasive procedure that may lack precision and is not ideal for routine clinical use. As a result, there is growing interest in non-invasive alternatives, such as the analysis of extracellular vesicles (EVs) present in uterine fluid. These vesicles are considered a form of noninvasive liquid biopsy and may reflect the molecular status of the endometrium at the time of the sampling. This study aimed to investigate the transcriptomic profile of uterine fluid-derived EVs (UF-EVs) at the time of frozen embryo transfer (FET) in 250 women undergoing IVF and to evaluate whether these profiles correlate with clinical pregnancy outcomes following ET.
Methods: This prospective multicentric cohort study include 48 infertile women under the age of 40, all undergoing their first frozen embryo transfer (FET) following IVF treatment. Uterine fluid samples were collected during the mid-luteal phase, specifically 7 days after the LH surge, one cycle prior to ET. RNA-sequencing was performed to characterize the transcriptomic landscape of UF-EVs., and differential gene expression was then correlated with the achievement of clinical pregnancy.
Results: Among the 48 participants, 19 (40%) achieved a clinical pregnancy. Expressed genes, defined as those showing at least 1 count per million (CPM) reads in at least 19 samples, totaled 15,229 across all samples. Clustering and principal component analysis (PCA) based on the entire transcriptome, as well as the top 5,000 and 500 most variable genes, did not reveal a clear separation between PG and NPG groups; however, DGE analysis identified 184 genes significantly upregulated and 3 genes downregulated in the PG group relative to the NPG group. Gene ontology analysis revealed that the PG group showed significant enrichment in biological processes such as protein localization to the endoplasmic reticulum, translation initiation, RNA catabolism, and cytoplasmic translation. Conversely, pathways related to cellular component maintenance and amyloid-beta clearance were diminished in the PG group. Cellular component enrichment analysis indicated that genes upregulated in the PG group were associated with ribosomes, mitochondrial membranes, the respiratory chain, and protein complexes. In terms of molecular function, enriched categories included ribosomal structure and translation initiation factors, while passive transmembrane transporter activity was notably reduced.
Conclusion: Distinct transcriptomic patterns in UF-EVs were observed between IVF patients who achieved clinical pregnancy and those who did not. The differentially expressed genes are involved in key cellular functions that align with known mechanisms of endometrial receptivity during the implantation window. These findings suggest that transcriptomic analysis of UF-EVs offers promising potential as a non-invasive, biologically informative tool for assessing endometrial receptivity, potentially serving as an alternative to current invasive biopsy-based methods. Nonetheless, this analysis is preliminary and limited by the small sample size of 48 patients. The goal of the study is to reach a cohort of 250 patients to strengthen the findings and provide more definitive insights into the clinical applicability of UF-EV profiling in IVF.