Decreased CD44v3 Expression Impairs Endometrial Stromal Cell Decidualization in Women With Recurrent Implantation Failure

Abstract BackgroundThe precise pathogenesis of poor endometrial receptivity in recurrent implantation failure (RIF) still remains unclear. This study aims to explore the effects of different CD44 isoforms in the mid-secretory phase endometrium on endometrial receptivity in women with RIF.MethodsMid-secretory phase endometrial tissue samples were obtained from two groups of women who had undergone IVF: a) 24 patients with RIF, b) 18 patients with infertility due to tubal obstruction, who had achieved a successful clinical pregnancy after the first embryo transfer in IVF (control group). Identification of differentially expressed CD44 isoforms in endometrial tissues was assessed with immunohistochemistry, qPCR and western blotting. Effects of CD44v3 overexpression and knockdown on proliferation and decidualization of Immortalized human endometrial stromal cells (T-HESCs) and primary HESCs were investigated by qPCR and Western blot. A heterologous co-culture system of embryo implantation was constructed to mimics the process of trophoblast invasion during implantation.ResultsCD44v3 was significantly higher expressed in mid-secretory phase of endometrial stromal cells than proliferation phase, but was notably lower in RIF patients. The expression of decidualization markers, prolactin (PRL) and insulin like growth factor binding protein-1 (IGFBP1), was notably decreased following CD44v3 knockdown, whereas the expression levels of both PRL and IGFBP1 increased after CD44v3 overexpression in HESCs. Furthermore, the CD44v3-knockdown HESCs displayed a significantly deficiency in supporting trophoblast outgrowth through a co-culture system of embryo implantation; however, CD44v3 overexpression in HESCs promoted trophoblast outgrowth.ConclusionThe reduced expression of CD44v3 suppresses HESCs proliferation and decidualization, which might play a pivotal role in poor endometrial receptivity in women with RIF.