Evaluation of extracellular vesicles and gDNA from culture medium as a possible indicator of developmental competence in human embryos

Abstract

Summary Human embryos generated in vitro have a high incidence of chromosomal abnormalities that negatively affect pregnancy rate. Embryos generated in vitro secrete extracellular vesicles (EVs) into the culture medium that could be used potentially as indicators of embryo competence. This research aimed to evaluate the concentration and size of EVs and their gDNA content as an indicator of developmental competence in human embryos. Human embryos generated by intracytoplasmic sperm injection (ICSI) were classified morphologically as of either TOP, FAIR or POOR quality. Culture medium and developmentally arrested embryos (which were not able to be used for embryo transfer) were collected. Microvesicles, exosomes (MV/Exo) and apoptotic bodies (ABs) were isolated from culture medium. Nanoparticle tracking analysis (NTA) and array comparative genomic hybridization (aCGH) analysis were performed to evaluate EVs and their gDNA content. From NTA, the diameter (mean) of MVs/Exo from TOP quality embryos was higher (112.17 nm) compared with that of FAIR (108.02) and POOR quality embryos (102.78 nm) (P < 0.05). aCGH analysis indicated that MVs/Exo and ABs carried gDNA with the presence of 23 chromosome pairs. However, when arrested embryos were compared with their respective MVs/Exo and ABs, the latter had an increased rate of chromosomal abnormalities (24.9%) compared with embryos (8.7%) (P < 0.05). In conclusion, the size of EVs from culture medium might be an alternative for evaluating competence of human embryos, however more studies are needed to validate the use of gDNA from EVs as an indicator of embryo competence.

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

“…From such findings, molecular determinants of implantation success [3, 31, 32] have been identified. These substantiate that embryo development [32–35] and endometrial receptivity [29, 36–39] are temporally regulated by intricate signalling networks [40]. With this knowledge we can (i) develop diagnostics that screen endometrial and embryo samples for receptivity/competency markers [14, 16, 24, 26, 30], thereby enabling synchronized timing of embryo transfer, and (ii) design therapeutic entities that deliver and reprogram the non‐receptive endometrium, [41, 42] thus improving implantation rates in ART.…”

“…In recent years, EVs have been detected in ESM and UFs obtained from human [33, 53, 77, 78, 80–82, 124, 125], bovine [55, 73, 79, 126–129], ovine [54, 57], porcine [76, 130], and murine [74, 131] species, suggesting that EVs may be an evolutionarily‐conserved function in reproductive biology (Table 1). The functional spectrum of EVs in reproductive biology is continuously expanding [63, 132–135], implicating EVs in gamete development and function (i.e., sperm activation [136], capacitation [137], acrosome reaction [138, 139], and oocyte maturation [140–142]), fertilisation [143], embryo development [144], implantation [43, 44, 66, 145] and invasion [43, 44, 66], endometrial receptivity [84, 146] and embryo‐maternal crosstalk [147].…”

“…Functionally, EVs are present across key stages of embryo implantation, including apposition [84], attachment (adhesion) [43, 44, 66], and invasion [44, 66, 80] into the maternal endometrium (Figure 1). To understand their mechanisms of action, particularly their ability to deliver functional biomolecules that modify target cell composition and phenotype, various omics strategies (quantitative mass spectrometry‐based proteomics, transcriptomics, genomics) have been employed [33, 77, 80, 84]. In this review, we discuss recent achievements in understanding the functional role of EVs (from embryo and maternal sources) in embryo implantation.…”

Non-Invasive Preimplantation Genetic Testing for Aneuploidy and the Mystery of Genetic Material: A Review Article

“…In the same study, however, they evaluated the diameter of EVs in comparison with embryo quality and discovered that the embryos with the best quality on day three had a larger EV diameter compared to poor-quality embryos. The authors of the said study also performed aCGH on developmentally arrested human embryos as well as on media culture samples and discovered a lower rate of chromosome abnormalities in the arrested embryos, rather than in their corresponding EVs, suggesting that the self-correcting mechanisms of aneuploid embryos could explain this [ 17 ]. As Palliger et al predicted in their study, the implementation of the measurement of EV concentration under standardized protocols could offer a simple, non-invasive, and inexpensive test, which could ultimately contribute to choosing the most prosperous embryo with the highest chance of implantation in a receptive endometrium [ 16 ].…”

The Complicated Effects of Extracellular Vesicles and Their Cargos on Embryo Implantation

“…Interestingly, only good-prognosis embryos induced the observed effects while degenerated embryos failed to initiate any changes (33). Recently, an encouraging study reported that the size of EVs from culture medium of human embryos might be an alternative for evaluating their developmental competence (53). In the process of in vitro culture, the mean diameter of MVs/Exo from top quality embryos was higher (112.17 nm) than that of fair (108.02 nm) and poor quality embryos (102.78 nm) (P < 0.05) (53).…”