Extracellular vesicles secreted during blastulation show viability of bovine embryos

Abstract

Extracellular vesicles (EVs) secreted by blastocysts may be clinically relevant, as indicator of embryo viability on in vitro fertilization. We tested if the characteristics of EVs secreted during blastulation are related to embryo viability. Morulae were individually cultured in SOF media depleted of EVs until day 7.5 post IVF. Viable embryos were determined by a system of extended in vitro culture of bovine embryos until day 11 (post-hatching development). Afterward, a retrospective classification of blastocyst and culture media was performed based on blastulation time (early blastulation (EB) or late blastulation (LB)) and post-hatching development at day 11 (viable (V) or non-viable embryo (NV)). A total of 254 blastocysts and their culture media were classified in four groups (V-EB, NV-EB, V-LB, NV-LB). Group V-EB had a larger blastocyst diameter (170.8 μm), higher proportion of good-quality blastocysts (77%) and larger mean size of population of EVs (122.9 nm), although the highest concentration of EVs (5.75 × 109 particles/mL) were in group NV-EB. Furthermore, small RNA sequencing detected two biotypes, miRNA (86–91%) and snoRNA (9–14%), with a total of 182 and 32 respectively. In differential expression analysis of miRNAs between V versus NV blastocysts, there were 12 miRNAs upregulated and 15 miRNAs downregulated. Binary logistic regression was used to construct a non-invasive novel model to select viable embryos, based on a combination of variables of blastocyst morphokinetics and EVs characteristics, the ROC-AUC was 0.853. We concluded that characteristics of EVs secreted during blastulation vary depending on embryo quality.

The Oviductal Extracellular Vesicles’ RNA Cargo Regulates the Bovine Embryonic Transcriptome

“…El Hajj et al [38] suggested that decreased SNORDs promoter region methylation in ICSI children may modulate cancer susceptibility, based on the identification of SNORDs such as SNORD11 as being differentially methylated in ICSI versus control umbilical cord blood samples, showing a relationship to processes during early embryonic development. Interestingly, several SNORDs have been identified in EVs secreted by embryos during in vitro culture [39]. From a total of 32 snoRNAs identified, two (SNORD110, SNORD81) were exclusively present in media from viable embryos, whereas media from non-viable embryos had three exclusive snoRNAs (SCARNA24, SNORD97, SNORD48), indicating them as potential biomarkers of embryo viability.…”

MicroRNAs from Extracellular Vesicles Secreted by Bovine Embryos as Early Biomarkers of Developmental Competence

“…Preimplantation embryos from different species, including human, pig, mouse, and bovine, secrete EVs that can modify gene expression in maternal cells or in other embryos [8][9][10]. The characteristics of EVs, including their concentration, size, distribution, and content, might reflect embryo quality, thus making them potential markers of embryonic developmental competence [10][11][12][13]. In fact, the most competent bovine embryos secrete fewer but larger EVs during blastulation [12,13].…”

“…The characteristics of EVs, including their concentration, size, distribution, and content, might reflect embryo quality, thus making them potential markers of embryonic developmental competence [10][11][12][13]. In fact, the most competent bovine embryos secrete fewer but larger EVs during blastulation [12,13].…”

Extracellular Vesicles, the Road toward the Improvement of ART Outcomes

“…Based on the broad-spectrum possibilities for EVs application, EVs have been postulated as potential non-invasive biomarkers. For example, EVs can be used as a biomarker for embryo quality [90][91][92] to select good embryos before transferring them to female recipients or to know the receptivity/health of a uterus before performing an embryo transference [93]. In addition, the increasing knowledge about the role of EVs on reproductive events and ART efficiency will lead to the next challenge for the biology of reproduction field: the large-scale production of EVs to use them as additives to gametes and embryo culture media.…”