BackgroundSuccessful establishment of pregnancy hinges on appropriate communication between the embryo and the uterus prior to implantation, but the nature of this communication remains poorly understood. Here, we tested the hypothesis that the endometrium is receptive to embryo-derived signals in the form of RNA.MethodsWe have utilized a non-contact co culture system to simulate the conditions of pre implantation environment of the uterus. We bioorthogonally tagged embryonic RNA and tracked the transferred transcripts to endometrium. Transferred transcripts were separated from endometrial transcripts and sequenced. Changes in endometrial transcripts were quantified using quantitative PCR.ResultsWe show that three specific transcripts are transferred to endometrial cells. We subsequently demonstrate a role of extracellular vesicles (EVs) in this process, as EVs obtained from cultured trophoblast spheroids incubated with endometrial cells induced down-regulation of all the three identified transcripts in endometrial cells.Finally, we show that EVs/nanoparticles captured from conditioned culture media of viable embryos as opposed to degenerating embryos induce ZNF81 down-regulation in endometrial cells, hinting at the functional importance of this intercellular communication.ConclusionUltimately, our findings demonstrate the existence of an RNA-based communication which may be of critical importance for the establishment of pregnancy.

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RESEARCH QUESTION Endometriosis is a common gynecological disease defined by the presence of endometrium-like tissue outside uterus. This complex disease, often accompanied by severe pain and infertility, causes significant medical and socioeconomic burden; hence, novel strategies are sought for treatment of endometriosis. Here, we set out to explore cytotoxic effects of a panel of compounds to find toxins with different efficiency in eutopic versus ectopic cells, thus highlighting alterations in the corresponding molecular pathways. DESIGN Effect of 14 compounds on cellular viability was established in a cohort of paired eutopic and ectopic endometrial stromal cell samples from 11 patients. The biological targets covered by the panel included pro-survival enzymes, cytoskeleton proteins, proteasome, and cell repair machinery. RESULTS We showed that protein kinase inhibitors GSK690693, ARC-775, and sorafenib, proteasome inhibitor bortezomib, and microtubule-depolymerizing toxin MMAE, were more effective in eutopic cells. In contrast, 10 M anthracycline toxin doxorubicin caused cellular death in ectopic cells more effectively than in eutopic cells. The large-scale sequencing of mRNA isolated from doxorubicin-treated and control cells indicated different survival strategies in eutopic versus ectopic endometrium. CONCLUSIONS Overall, our results confirm the evidence of large-scale metabolic reprogramming in endometriotic cells, which underlies the observed differences in sensitivity towards toxins. The enhanced efficiency of doxorubicin interfering with redox equilibria and/or DNA repair mechanisms pinpoints key players that can be potentially used for selective targeting of ectopic lesions in endometriosis.