Abstract
Extracellular vesicles are nanoparticles secreted by cell and have been proposed as suitable markers to identify competent embryos produced in vitro. Characterizing EVs secreted by individual embryos is challenging because culture medium itself contributes to the pool of nanoparticles that are co-isolated. To avoid this, culture medium must be depleted of nanoparticles that are present in natural protein source. The aim of this study was to evaluate if the culture medium subjected to nanoparticle depletion can support the proper in vitro development of bovine embryos. Zygotes were cultured in groups on depleted or control medium for 8 days. Nanoparticles from the medium were characterized by their morphology, size and expression of EVs surface markers. Isolated nanoparticles were labelled and added to depleted medium containing embryos at different developmental stages and evaluated after 24 hours at 2, 8-16 cells, morula and blastocyst stages. There were no statistical differences on blastocyst rate at day 7 and 8, total cell count neither blastocyst diameter between groups. However, morphological quality was better in blastocysts cultured in non-depleted medium and the expression of SOX2 was significantly lower whereas NANOG expression was significantly higher. Few nanoparticles from medium had a typical morphology of EVs but were positive to specific surface markers. Punctuated green fluorescence near the nuclei of embryonic cells was observed in embryos from all developmental stages. In summary, nanoparticles from culture medium are internalized by in vitro cultured bovine embryos and their depletion affects the capacity of medium to support the proper embryo development.
Highlights
In vitro produced (IVP) embryos can be transferred to a maternal recipient in the one-cell stage; in most species, embryos are usually cultured for several days before transfer, to reach a more advanced developmental stage
Global Total (GT) and GTd were analyzed by Nanoparticles Tracking Analysis (NTA) to determine the presence and characteristics of particles
From the results of this work, we conclude that medium used for embryo culture is a source of extracellular vesicles (EVs) and/or exomeres-like nanoparticles which pass through the zona pellucida and are internalized by embryonic cells
Summary
In vitro produced (IVP) embryos can be transferred to a maternal recipient in the one-cell stage; in most species, embryos are usually cultured for several days before transfer, to reach a more advanced developmental stage (e.g. blastocyst). In vitro environment alters embryonic developmental kinetics, gene expression pattern, cell signaling, metabolism and chromosome structure among others (Wrenzycki et al, 2001; Rizos et al, 2003; Rodríguez-Alvarez et al, 2010; Cagnone and Sirard, Copyright © The Author(s). Those alterations contribute to the low competence of IVP embryos, leading to high embryonic loss before embryo-maternal recognition, as well as to long term effects such as pregnancy loss and lower birth rates (Thatcher et al, 2001; Diskin and Morris, 2008; Berg et al, 2010; Hansen et al, 2010; Besenfelder et al, 2012; Perkel et al, 2015)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
