Endometrial stromal cells from women with repeated implantation failure display impaired invasion towards trophoblastic spheroids.

The success rate of in vitro fertilization (IVF) remains limited in some women despite transfers of good-quality embryos in repeated attempts. There is no reliable tool for assessing endometrial receptivity. This study aimed to assess the interaction between decidualized human primary endometrial stromal cells (1°-EnSC) and human embryonic stem cell-derived trophoblastic spheroids (BAP-EB) and to compare the invasion ability of decidualized 1°-EnSC towards BAP-EB between women attaining live birth in the first IVF cycle and those with repeated implantation failure (RIF). The invasion of the decidualized human endometrial cell line (T-HESC) and 1°-EnSC towards BAP-EB was studied. Real-time quantitative PCR and immunocytochemistry were employed to determine the expression of decidualization markers at mRNA and protein levels, respectively. Trophoblast-like BAP-EB-96h, instead of early trophectoderm (TE)-like BAP-EB-48h, facilitated the invasion ability of decidualized T-HESC and decidualized 1°-EnSC. Human chorionic gonadotropin at supra-physiological levels promoted the invasiveness of decidualized 1°-EnSC. The extent of BAP-EB-96h-induced invasion was significantly stronger in decidualized 1°-EnSC from women who had a live birth in the first IVF cycle when compared to those with RIF. While no difference was found in the expression of decidualization markers, PRL and IGFBP1 among two groups of women, significantly lower HLA-B was detected in the non-decidualized and decidualized 1°-EnSC from women with RIF. Collectively, the findings suggested that the invasion of decidualized 1°-EnSC towards trophoblast-like BAP-EB-96h was higher in women who had a live birth in the first IVF cycle than those with RIF.