Extracellular vesicles: a promising tool for assessment of embryonic competence

Purpose of review Extracellular vesicles have recently emerged as a promising field of research due to their pivotal roles in intercellular communication and potential to serve as biomarkers. This review focuses on extracellular vesicles secreted by the human preimplantation embryo. The most recent findings on embryo-derived extracellular vesicles are described and discussed, as well as current technical challenges to study them. Recent findings So far, only a few studies have addressed extracellular vesicles of embryonic origin and explored their potential as biomarkers for embryo selection. Two main hypotheses have driven interest in studying extracellular vesicles in IVF embryo-conditioned culture media. On the one hand, the potential roles of extracellular vesicles in mediating the embryo-endometrial crosstalk for proper implantation. On the other hand, the profile of secreted extracellular vesicles as an indicator of embryonic fitness irrespective of any involvement or communication with the endometrium. Embryo-derived extracellular vesicles have already been investigated to design diagnostic tests for embryo viability, however with small sample sizes or without extensive technology validation. Summary Extracellular vesicles offer indeed a novel means to assess embryonic fitness. Further validation studies, technology development and more complex study designs are certainly required to implement the profiling of embryonic extracellular vesicles as a diagnostic test for embryo selection.