Sperm aren’t alone on their journey to fertilization. Tiny vesicles help them mature; a Czech discovery may contribute to improving assisted reproduction

Researchers from the Institute of Biotechnology of the Czech Academy of Sciences at the BIOCEV Center, the Faculty of Science at Charles University, and the Czech University of Life Sciences in Prague were the first to comprehensively describe tiny membrane vesicles released from various parts of the porcine epididymis and demonstrated that they bind to sperm and transfer molecules essential for their maturation. The results were published in the prestigious scientific Journal of Extracellular Vesicles.

By combining modern methods, including mass spectrometry, electron microscopy, and confocal microscopy, the researchers not only characterized the composition of these vesicles but also directly observed their interaction with sperm and the transfer of their molecular contents. The research was conducted in Vestec and Prague using biological material from Czech breeding farms.

Extracellular vesicles represent a natural cellular communication system. They transport proteins and other biologically active molecules that influence the function of target cells. In the reproductive system, they play a key role in sperm maturation, the acquisition of motility, and the ability to fertilize an egg.

For the first time, the Czech team compared vesicles from all three parts of the porcine epididymis as well as from seminal plasma. They identified thousands of proteins whose composition varies between the different parts and corresponds to the various stages of sperm maturation. At the same time, they demonstrated that the vesicles directly bind to sperm and transfer their contents to them. Furthermore, experiments showed that without surface proteins, the vesicles lose their ability to bind to sperm.

“Our results show that sperm are not merely passive carriers of genetic information. They actively communicate with their environment and, during maturation, acquire molecules from epididymal cells that are essential for their proper function. A better understanding of this process may contribute in the future to the development of new methods of assisted reproduction and the diagnosis of male infertility,” says Pavla Postlerová of the Institute of Biotechnology at the Czech Academy of Sciences, the principal investigator of the research project supported by the Czech Science Foundation.

Visualization of the binding and fusion of extracellular vesicles with sperm using advanced microscopic techniques and their 3D spatial visualization.

The study also describes a new method for isolating these vesicles that preserves their biological activity. The findings may serve as a basis for further research in reproductive biology and the development of new procedures for in vitro fertilization and assisted reproduction in livestock. Because the pig is an important biomedical model with reproductive physiology similar to that of humans, the results may also contribute to a better understanding of human reproduction and support future clinical applications.

Publication: Kraus V., Dolečková B., Frolíková M., Šanovec O., Svěpáková D., Pilsová Z., Pilsová A., Komrsková K., Šimoník O., Postlerová P. Molecular Profiling of Extracellular Vesicles Isolated from Boar Reproductive Fluids. Journal of Extracellular Vesicles. 2026;15 (7). https://doi.org/10.1002/jev2.70329

Contact:

Pavla Postlerová
Institute of Biotechnology CAS
pavla.postlerova@ibt.cas.