Updating Research on Extracellular Vesicles of the Male Reproductive Tract in Farm Animals: A Systematic Review.

This systematic review examined research studies on extracellular vesicles (EVs) of the male reproductive tract in livestock species to summarize the research topics and methodologies used, key findings, and future directions. PubMed and Scopus were searched for time ranges up to 1 September 2024, and 1383 articles were identified. The application of screening and eligibility criteria resulted in the selection of 79 articles focusing on male reproductive EVs in livestock. Porcine and bovine male reproductive EVs were the most studied. A variety of EV isolation techniques were used, with ultracentrifugation being the most common. Characterization of male reproductive EVs in livestock was a weak point, with only 24.05% of the articles characterizing EVs according to MISEV guidelines. Inadequate characterization of EVs compromises the reliability of results. The results of 19 articles that provided a good characterization of EVs showed that male reproductive EVs from livestock species are phenotypically and compositionally heterogeneous. These papers also showed that these EVs would be involved in the regulation of sperm functionality. Research on male reproductive EVs in livestock species remains scarce, and further research is needed, which should include appropriate characterization of EVs and aim to find efficient methods to isolate them and assess their involvement in the functionality of spermatozoa and the cells of the female genital tract.