Background: Endometrial receptivity issues represent a potential source of implantaion failure. It is very important to investigate the expression of endometrial receptive markers in the endometrium during implantation. Therefore, we examined whether it would be possible to analyze endometrial receptivity using cells from embryo transfer catheters. In addition, we analyzed the relationship between the gene expression profile associated with pregnancy from endometrial cells taken during embryo transfer.
Methods: A total of 88 cycles from 88 consenting patients were enrolled in this study. The tip of the embryo transfer (ET) catheter was cut and immersed in a dedicated reagent. Confirmation of cell distribution was carried out using a Papanicolaou stain (n=6) and immunocytochemistry (n=3). Protein expression was carried out by immunocytochemistry (n=12). Total RNA was extracted, and the expression of endometrial receptive markers (estrogen receptor α, progesterone receptor, and homeobox A10) were analyzed using quantitative reverse transcription polymerase chain reaction (n=67). we analyzed the relationship between the gene expression profile associated with pregnancy from endometrial cells.
Results: Samples collected from the ET catheter showed clear staining for endometrial cells. Most of the cells were endometrial epithelial cells. Cervical cells were not included. The protein expression of endometrial receptive markers in cells was also confirmed. Three genes were analyzed that are associated with endometrial receptivity. Progesterone receptor expression was 1.5-fold and homeobox A10 expression was 2-fold higher in patients who became non-pregnant group, compared to the pregnant group. Both increases were statistically significant (p < 0.05). Estrogen receptor α expression tended to be higher in the non-pregnant group, but there was no significant difference.
Conclusion: Our results suggest that endometrial receptivity can be evaluated using cells obtained from the ET catheter. This method may be useful for elucidating the cause of implantation failure by comparing a receptive and non-receptive endometrium at the time of ET.