Effect of peritoneal fluid from women with endometriosis on implantation in the mouse model

Objective: To investigate the potential role of peritoneal fluid (PF) from women with or without endometriosis in implantation in mice with use of the delayed implantation model. Design: A murine experimental model with markers of uterine receptivity and prospective comparison of the effects of human PF on implantation. Setting: Academic university and hospital program. Intervention(s): PF collected from women with and without endometriosis was injected intraperitoneally into recently mated mice. Main Outcome Measure(s): Implantation sites were counted in treated and untreated animals, and the alpha v beta 3 integrin was measured in the pregnant mouse uterus by immunohistochemistry with in situ hybridization. Leukemia inhibitory factor and the beta 3 subunit of alpha v beta 3 were measured by Northern blot during early pregnancy and after injections of PF. Result(s): Animals receiving PF from infertile women with endometriosis had a reduction in the number of implantation sites compared with animals that received PF from fertile women or from patients with recently treated endometriosis. In the mouse, expression of alpha v beta 3 and leukemia inhibitory factor peaked at the time of implantation and was reduced by injections of human PF from infertile patients with endometriosis. Conclusion(s): Leukemia inhibitory factor and alpha v beta 3 are coexpressed at the time of implantation in the mouse. PF from women with endometriosis has a detrimental effect on embryo implantation, perhaps by adversely affecting uterine receptivity. (Fertil Steril(R) 2000;74:41-8. (C) 2000 by American Society for Reproductive Medicin).