Extracellular vesicle mediated intercellular communication at the porcine maternal-fetal interface: A new paradigm for conceptus-endometrial cross-talk

Abstract

Exosomes and microvesicles are extracellular vesicles released from cells and can contain lipids, miRNAs and proteins that affect cells at distant sites. Recently, microvesicles containing miRNA have been implicated in uterine microenvironment of pigs, a species with unique epitheliochorial (non-invasive) placentation. Here we report a novel role of conceptus-derived exosomes/microvesicles (hereafter referred to as extracellular vesicles; EVs) in embryo-endometrial cross-talk. We also demonstrate the stimulatory effects of EVs (PTr2-Exo) derived from porcine trophectoderm-cells on various biological processes including the proliferation of maternal endothelial cells (PAOEC), potentially promoting angiogenesis. Transmission immuno-electron microscopy confirmed the presence of EVs in tissue biopsies, PTr2-Exo and PAOEC-derived EVs (PAOEC-Exo). RT-PCR detected 14 select miRNAs in CD63 positive EVs in which miR-126-5P, miR-296-5P, miR-16, and miR-17-5P were the most abundant angiogenic miRNAs. Proteomic analysis revealed EV proteins that play a role in angiogenesis. In-vitro experiments, using two representative cell lines of maternal-fetal interface, demonstrated bidirectional EVs shuttling between PTr2 and PAOEC cells. Importantly, these studies support the idea that PTr2-Exo and PAOEC-Exo containing select miRNAs and proteins can be successfully delivered to recipient cells and that they may have a biological role in conceptus-endometrial cross-talk crucial for the pregnancy success.

Embryonic extracellular vesicles as informers to the immune cells at the maternal–fetal interface

“…The target genes of these miRNAs are thought to mediate cellular activities such as adhesion and migration, suggesting that embryos could potentially modify the endometrial function [43]. The target genes of these miRNAs are thought to mediate cellular activities such as adhesion and migration, suggesting that embryos could potentially modify the endometrial function [43].…”

“…The porcine embryo-derived EV cargo also contains a variety of miRNA species with different targets on both epithelial and stromal cells. The target genes of these miRNAs are thought to mediate cellular activities such as adhesion and migration, suggesting that embryos could potentially modify the endometrial function [43]. miRNAs have also been identified in culture media of human blastocysts and were detected in biopsied trophectoderm cells, suggesting that they are released from blastocysts [44,45].…”

Roles of microRNAs in mammalian reproduction: from the commitment of germ cells to peri‐implantation embryos

“…Thus these miRNAs could be used to assess foetal health, although this requires validation with other mammalian species. Additionally, some miRNAs participate in the implantation process indirectly, such as by promoting the proliferation of trophoblast cells (Luo et al, ; Fu et al, ), by facilitating trophoblast migration (Bai et al, ; Luo et al, ; Fu et al, ), by inhibiting the apoptosis of trophoblasts (Pineles et al, ), and by participating in conceptus–endometrial crosstalk (Bidarimath et al, ).…”

“…Finally, early embryos may be enriched with a panel of parental miRNAs (Fig. 5), either through gametes (Tang et al, 2007;Yuan et al, 2016) or embryo-maternal crosstalk (Saadeldin et al, 2015;Bidarimath et al, 2017). Exosomes and cell-membrane-derived micro-and nano-vesicles could be the main medium for this embryo-maternal crosstalk (Diehl et al, 2012;Saadeldin et al, 2015), however, miRNAs could also be carried through the circulatory system by apoptotic bodies, RNA-binding lipoproteins and Argonaute protein complex (Ling, Bao-feng, & Jing, 2013;Sohel, 2016).…”

“…(3) miRNAs regulate pregnancy by mediating adhesion molecules, vasculature and angiogenesis miRNAs involved in the implantation process can be categorized into two groups, anti-or pro-implantation miRNAs (Fig. 5); these miRNAs are potent regulators of many genes related to adhesion, angiogenesis, and vasculature (see Table S5), as well as foetal-maternal immune tolerance following endometrial reception of the conceptus (Bidarimath et al, 2014(Bidarimath et al, , 2015. Alterations in expression of these miRNAs in the uterine endometrium could cause implantation failure as well as disease (Hiroki et al, 2010).…”