Endometrial transcriptome profiling of patients with recurrent implantation failure (RIF) during hormone replacement therapy (HRT) cycles
The molecular mechanisms underlying window of implantation (WOI) displacement in patients with recurrent implantation failure (RIF) remain unclear. This study aims to explore the transcriptomic signatures of endometrium with normal and displaced WOIs during HRT cycles and to identify the causes of endometrial receptivity (ER) abnormalities and WOI displacement in RIF patients. 40 RIF patients were recruited and underwent personalized embryo transfer (pET) guided by the predicted results of endometrial receptivity diagnosis (ERD) model. Transcriptome analysis of endometrium from patients with clinical pregnancies after pET was performed to identify differentially expressed genes (DEGs) associated with WOI displacement. The ERD results indicated that 67.5% of RIF patients (27/40) were non-receptive in the conventional WOI (P+5) of the HRT cycle. The clinical pregnancy rate in RIF patients improved to 65% (26/40) after ERD-guided pET, indicating the effectiveness of transcriptome-based WOI prediction. Among the 26 patients with clinical pregnancy, the gene expression profiles of P+5 endometrium from advanced (n=6), normal (n=10) and delayed (n=10) WOI groups were significantly different from each other.  10 DEGs (CES4A, LRRC1, SLC25A48, TM4SF4, DPP4, CXCR1, CXCR2, OSM, LCN2 and TNFRSF10C ) identified among P+5 endometrium of 3 groups were involved in immunomodulation, transmembrane transport and tissue regeneration, which could accurately classify the endometrium with different WOIs. Overall design: The diagnostic value of the eight gene expression signatures was evaluated by receiver operator characteristic analysis. This model was validated by an external clinical patient cohort. All samples were surplus tissue from endometrial biopsies obtained from patients for diagnostic purposes. The timing of the endometrial biopsy was 5 days after ovulation (evaluated by ultrasonography), which is equivalent to LH + 7 in a natural cycle.