Extracellular vesicles offer clues to cattle reproduction

Improving bovine reproductive efficiency requires a better understanding of how the maternal reproductive tract interacts with the developing embryo. To study this complex communication, scientists are developing in vitro models that better mimic the oviduct’s natural environment. Within this environment, extracellular vesicles, or EVs, regulate processes that support embryo health.

In a study conducted by Rosane Mazzarella from the National Institute for Agricultural and Food Research and Technology, published in Molecular & Cellular Proteomics, scientists examined the role of EVs in maternal–embryonic communication by comparing their protein cargo inside and outside of the maternal womb. Researchers collected EVs from the oviductal fluid of cyclic and pregnant heifers as well as from the conditioned media of oviductal explants removed from heifers and cultured in the lab, either with or without embryos. 

About 78% of embryo-associated proteins overlapped between pregnant heifers and explants cultured with embryos, indicating that maternal-embryonic communication can be partially mimicked outside the body. However, label-free quantification revealed that EVs collected directly from the oviducts of pregnant animals and those produced by explants cultured with embryos displayed both qualitative and quantitative differences in their protein profiles. Notably, 49 EV proteins were unique to pregnant heifers. Among them, centromere protein E, which plays a role in cell division, is significant in identifying healthy, rapidly developing cow embryos and plays a key role in maintaining chromosome stability. Another protein, JAK3, helps relay signals from certain immune-related molecules and may promote embryonic cell survival and growth. These findings suggest that EVs from the natural reproductive environment may offer more robust support for embryo development.

Taken together, while laboratory systems replicate many features of maternal–embryonic signaling, EVs from pregnant heifers appear to deliver a more complete set of developmental cues, offering potential for enhancing artificial embryo culture systems via supplementation.