Treatment with low-dose aspirin increased the level LIF and integrin β3 expression in mice during the implantation window.

Embryo implantation is the group of processes by which the developing blastocyst adheres to, and embeds into, the receptive endometrium. Changes in the expression of molecules on the cell surface have been seen in the conversion of the endometrial surface from a non-receptive to a receptive state. Cell adhesion molecules like integrins, or soluble factors such as Leukemia inhibitory factor (LIF) have been identified to play an important role during the implantation period. Studies have suggested that low-dose aspirin (<100 mg/d) treatment can improve implantation rate, ovarian responsiveness, and pregnant rates in IVF patients. The mechanism of this increased implantation rate is unclear, and in this study we hypothesised that the expression of integrin β3 or LIF may be altered, during implantation window, by treatment with low-dose aspirin. Female mice were treated with 0.9 mg/ml aspirin daily for 15 days and then were mated. The protein or mRNA levels of LIF and integrin β3 in the endmetrium were determined on the day 4 post-coitus using immuno-fluorescence and RT-PCR. We found the expression of LIF or integrin β3 was significantly increased in the endometrium of mice that were treated with low dose of aspirin by immuno-fluorescence. In addition, the mRNA level of LIF or integrin β3 on the endometrium of aspirin treated mice was also significantly increased compared to untreated mice. We conclude that low dose aspirin alters the expression of endometrial LIF and integrin β3 and that these changes may increase endometrial receptivity.