The Dynamic Change of microRNA Expression Profile in Endometrium and Plasma During the Periimplantation Window

Background: MicroRNAs (miRNAs) regulate gene expression critical for embryo implan-tation, but integrated analyses of miRNA changes in both endometrium and plasma dur-ing the peri-implantation period are lacking. Methods: A total of 62 endometrium and 62 plasma samples were collected from participants undergoing hormone treatment cycles between day P+3 to P+7. Next-generation sequencing (NGS) assay was used to profile miRNA expression levels. To identify the dynamic differentially expressed (DE) miRNAs, we compared the following groups: P+3/P+4, P+4/P+5, P+5/P+6, and P+6/P+7. Then, we perform functional miRNA-target interaction (MTI) and pathway enrichment analysis to understand the biological functions of DE miRNAs. Results: A total of 76 DE miRNAs in endometrium and 48 in plasma were identified. These miRNAs are involved in pathways related to implantation, such as cell senescence, cell growth, apoptosis, focal adhesion, autophagy, platelet activation and signaling. Ten DE miRNAs overlapped between en-dometrial tissue and plasma, with seven showing consistent dynamic expression changes. Further analysis revealed a high similarity in the biological pathways and functions in-volving the target genes of DE miRNAs in both endometrium and plasma. Conclusions: Dynamic miRNA expression changes in both endometrium and plasma reflect key bio-logical processes regulating human embryo implantation.