Endometrial exosomes/microvesicles in the Uterine Microenvironment: A New Paradigm for Embryo-Endometrial Cross Talk at Implantation

PLoS One. 2013;8(3):e58502. doi: 10.1371/journal.pone.0058502. Epub 2013 Mar 13.

Abstract

Exosomes are nanoparticles (∼100 nm diameter) released from cells, which can transfer small RNAs and mRNA via the extracellular environment to cells at distant sites. We hypothesised that exosomes or the slightly larger microvesicles (100-300 nm) are released from the endometrial epithelium into the uterine cavity, and that these contain specific micro (mi)RNA that could be transferred to either the trophectodermal cells of the blastocyst or to endometrial epithelial cells, to promote implantation. The aim of this study was to specifically identify and characterise exosomes/microvesicles (mv) released from endometrial epithelial cells and to determine whether exosomes/mv are present in uterine fluid. Immunostaining demonstrated that the tetraspanins, CD9 and CD63 used as cell surface markers of exosomes are present on the apical surfaces of endometrial epithelial cells in tissue sections taken across the menstrual cycle: CD63 showed cyclical regulation. Exosome/mv pellets were prepared from culture medium of endometrial epithelial cell (ECC1 cells) and from uterine fluid and its associated mucus by sequential ultracentifugation. Exosomes/mv were positively identified in all preparations by FACS and immunofluorescence staining following exosome binding to beads. Size particle analysis confirmed the predominance of particles of 50-150 nm in each of these fluids. MiRNA analysis of the ECC1 cells and their exosomes/mv demonstrated sorting of miRNA into exosomes/mv: 13 of the 227 miRNA were specific to exosomes/mv, while a further 5 were not present in these. The most abundant miRNA in exosomes/mv were hsa-miR-200c, hsa-miR-17 and hsa-miR-106a. Bioinformatic analysis showed that the exosome/mv-specific miRNAs have potential targets in biological pathways highly relevant for embryo implantation. Thus exosomes/mv containing specific miRNA are present in the microenvironment in which embryo implantation occurs and may contribute to the endometrial-embryo cross talk essential for this process.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Biomarkers / metabolism
  • Cellular Microenvironment*
  • Embryo Implantation*
  • Endometrium / cytology*
  • Epithelial Cells / cytology
  • Epithelial Cells / metabolism
  • Exosomes / metabolism*
  • Female
  • Humans
  • Intracellular Membranes / metabolism
  • Menstrual Cycle / metabolism
  • MicroRNAs / genetics
  • MicroRNAs / metabolism
  • Mucus / metabolism

Substances

  • Biomarkers
  • MicroRNAs

Grant support

Work in the Salamonsen Laboratory was supported by the National Health and Medical Research Council of Australia, Program grant #494802 and Fellowship #1002028 to LAS (www.nhmrc.gov.au). The Victorian Government's Operational Infrastructure Support Program (www.business.vic.gov.au/industries/science-technology-and-innovation/programs/medical-research-operational-infrastructure-program). YHN was the recipient of an Endeavour Fellowship from the Australian Government (http://www.innovation.gov.au/INTERNATIONALEDUCATION/ENDEAVOURAWARDS). The Rome laboratory is supported by Fondation pour la Recherche Médicale (www.frm.org), Association Française de recherche sur les Myopathies (www.afm-telethon.com), Association Française de Diabétologie (www.sfdiabete.org) and an INRA specific grant - ANSSD (www.international.inra.fr). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. PHI Data Audit 12–28.