Trophoblast derived extracellular vesicles specifically alter the transcriptome of endometrial cells and may constitute a critical component of embryo-maternal communication

Abstract

Background The period of time when the embryo and the endometrium undergo significant morphological alterations to facilitate a successful implantation—known as “window of implantation”—is a critical moment in human reproduction. Embryo and the endometrium communicate extensively during this period, and lipid bilayer bound nanoscale extracellular vesicles (EVs) are purported to be integral to this communication. Methods To investigate the nature of the EV-mediated embryo-maternal communication, we have supplemented trophoblast analogue spheroid (JAr) derived EVs to an endometrial analogue (RL 95–2) cell layer and characterized the transcriptomic alterations using RNA sequencing. EVs derived from non-trophoblast cells (HEK293) were used as a negative control. The cargo of the EVs were also investigated through mRNA and miRNA sequencing. Results Trophoblast spheroid derived EVs induced drastic transcriptomic alterations in the endometrial cells while the non-trophoblast cell derived EVs failed to induce such changes demonstrating functional specificity in terms of EV origin. Through gene set enrichment analysis (GSEA), we found that the response in endometrial cells was focused on extracellular matrix remodelling and G protein-coupled receptors’ signalling, both of which are of known functional relevance to endometrial receptivity. Approximately 9% of genes downregulated in endometrial cells were high-confidence predicted targets of miRNAs detected exclusively in trophoblast analogue-derived EVs, suggesting that only a small proportion of reduced expression in endometrial cells can be attributed directly to gene silencing by miRNAs carried as cargo in the EVs. Conclusion Our study reveals that trophoblast derived EVs have the ability to modify the endometrial gene expression, potentially with functional importance for embryo-maternal communication during implantation, although the exact underlying signalling mechanisms remain to be elucidated.

Omics insights into extracellular vesicles in embryo implantation and their therapeutic utility

“…Indeed, a proportion of EVs identified in the uterine lumen during early pregnancy [55] have been shown to be uniquely contributed by the foetus [34,56,57,150,154], and levels of placental EVs increase in human maternal circulation across gestation [155]. Embryo-derived EVs can interact with various cell types associated with the uterus (e.g., endometrium, immune [156] cells) to modulate processes implicated in receptivity [84,157,158] in addition to remodelling the extracellular matrix [158,159]-a critical network in supporting the development and implantation competence of human embryos [160]. Because of the very small quantity of EVs released by an embryo, cells of trophectodermal [84,[157][158][159] or embryonic [33,34,53,129] origin remain the most widely used approaches to understand their composition and function (Table 2).…”

“…Embryo-derived EVs can interact with various cell types associated with the uterus (e.g., endometrium, immune [156] cells) to modulate processes implicated in receptivity [84,157,158] in addition to remodelling the extracellular matrix [158,159]-a critical network in supporting the development and implantation competence of human embryos [160]. Because of the very small quantity of EVs released by an embryo, cells of trophectodermal [84,[157][158][159] or embryonic [33,34,53,129] origin remain the most widely used approaches to understand their composition and function (Table 2).…”

MicroRNAs in the Regulation of Endometrial Receptivity for Embryo Implantation

“…There is growing evidence suggesting that the endometrium also has an active role in selecting embryonic EVs based on the cargo profile, which could include miRNAs such as the let-7 family, miR-31, miR-101a, miR-199a, miR-200 and the aforementioned miR-661 [ 121 , 132 ]. Other studies have predicted that miRNAs derived from the blastocyst culture medium may potentially modulate endometrial epithelial proliferation and embryo attachment [ 31 , 130 , 133 ].…”

Synergies of Extracellular Vesicles and Microchimerism in Promoting Immunotolerance During Pregnancy

“…Further, sEVs containing activated matrix MMP-2 2 derived from cancer cells modulate extracellular matrix by degrading collagen and fibronectin to promote cell invasion and metastasis (156). Comparably, EVs derived from trophoblast spheroids can modulate major pathways in endothelial cells including extracellular matrix organization (157).…”