Reproduction Abstracts

Acquisition of uterine receptivity, an essential prelude for successful embryo implantation, is fully dependent on the development of adequate conditions for the attachment of the conceptus to the endometrial epithelium. The particular constituents of such ‘adequate conditions’ are not as yet defined and markers for a receptive endometrium are practically unavailable. Furthermore, the disappointing, poor rate of pregnancy, presently achieved following the transfer of high quality embryos makes implantation the rate-limiting step for the success of IVF. A substantial increase in pregnancy rate, induced by endometrial biopsyin patients with recurrent implantation failure, has been reported by us and confirmed by others. Along this line, we have later demonstrated that uterine dendritic cells (DCs) are crucial for implantation in mice. Taking these findings into account we raised the hypothesis that local injury generated by endometrial biopsy increases uterine receptivity by provoking inflammation. The overall goal of our study was to unveil the role of inflammation in successful implantation, further providing valuable clinical information that will be translated into diagnosis and treatment of infertility. Our experiments were specifically directed at i) characterization of the response of human endometrial cells to inflammatory-inducing agents, ii) examination of the effect of immune cells on endometrial cell differentiation, and iii) establishment of biomarkers for predicting implantation competence. The results of our study suggest that endometrial biopsy upregulates the expression of proinflammatory cytokines that recruit monocytes to the site of injury and may switch their differentiation into DC-like cells. These monocyte-derived DCs may trigger the epithelial cells to produce molecules that interact with the blastocyst, facilitating implantation.