Trophoblast derived extracellular vesicles specifically\xa0alter the transcriptome of endometrial cells and may constitute a critical component of embryo-maternal communication

Kasun Godakumara,Freddy Lättekivi,James Ord,Andres Salumets,Ülle Jaakma,Janeli Viil,Nageswara Rao Boggavarapu,Keerthie Dissanayake,Omid R Faridani,Alireza Fazeli,Kersti Jääger,Agne Velthut-Meikas

doi:10.1186/s12958-021-00801-5

Abstract

BackgroundThe 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.MethodsTo 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.ResultsTrophoblast 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.ConclusionOur 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.

Highlights

The period of time when the embryo and the endometrium undergo significant morphological altera‐ tions to facilitate a successful implantation—known as “window of implantation”—is a critical moment in human reproduction
The expression profile of RL95‐2 cellular transcriptome Endometrial analogue (RL95-2) cells treated with JAr spheroid derived extracellular vesicle (EV) (RJ) was clearly different from the untreated control (R) and the RL95-2 cells treated with HEK293 spheroidderived EVs (RH) (Fig. 2A)
It is apparent that the untreated RL95-2 cells and RL95-2 cells treated with HEK293 EVs are clustered relatively closely together, indicating that there was little or no effect on RL95-2 cells from HEK293 derived EVs

Summary

Introduction

The period of time when the embryo and the endometrium undergo significant morphological altera‐ tions to facilitate a successful implantation—known as “window of implantation”—is a critical moment in human reproduction. One of the hypotheses being investigated in this regard is the theory of embryo-maternal cross-talk which posits that the embryo and the endometrium undergo a complex set of “negotiations” prior to and during apposition, the first step of implantation, in the time period known as the “window of implantation” (WOI) [4, 5]. The crosstalk prepares both the embryo and the endometrium for a successful implantation by inducing specific biochemical alterations in the epithelial cells and the underlying uterine architecture [6, 7]. As embryo implantation is a temporally and spatially complex process, it likely involves several other mechanisms that are less known

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Conclusion