Abstract: THE ROLE OF CRISP3 IN REGULATING ENDOMETRIAL RECEPTIVITY IN REPEATED IMPLANTATION FAILURE
Repeated implantation failure (RIF) is a clinical scenario characterized by failure to achieve a positive pregnancy test after the transfer of a sufficient number of viable euploid embryos. Some RIF patients had a defective endometrial receptivity during the implantation window as compared to those with normal fertility. Identifying key factors influencing receptivity is essential for understanding the etiology of RIF and increasing the clinical pregnancy rates. The aim of this study was to identify key factors affecting endometrial receptivity with the use of human expanded potential stem cell derived trophoblastic spheroids as embryo surrogate. Analysis on published datasets of single-cell RNA sequencing of human endometrial tissues revealed that cysteine rich secretory protein 3 (CRISP3) was one of the upregulated genes in luminal epithelial cells during the secretory phase as compared to the proliferative phase. CRISP3 was also found to be one of the down-regulated genes in the luminal epithelial cells of patients with RIF at 7 days after luteinizing hormone surge (LH+7). Its expression was significantly higher in receptive endometrial epithelial cell (EEC) line (RL95-2) when compared to non-receptive EEC lines (AN3CA and HEC-1B). The expression levels of CRISP3 in primary EEC were further compared between endometrial tissues collected from receptive phase on LH+7 day (n=13) and pre-receptive phase on LH+2 day (n=6). It was found that significantly higher levels of CRISP3 was detected in EEC on LH+7 day. The functional role of endometrial CRISP3 was studied by the knockdown approach, followed by the attachment assay of the trophoblastic spheroid. It was shown that CRISP3 knockdown by siRNA in RL95-2 cells significantly reduced the attachment rate of the trophoblastic spheroids. The results of this study will provide some possible clues for understanding the mechanisms underlying RIF and identifying key factors for improving endometrial receptivity.
