Extracellular vesicles as emerging bioactive modulators in sperm cryopreservation: Mechanisms and therapeutic potentials

Sperm cryopreservation is a cornerstone of assisted reproduction and genetic conservation, yet the freeze-thaw process induces substantial structural and functional damage to spermatozoa. Recent progress in the field has positioned extracellular vesicles (EVs) as potential therapeutic tools, primarily because of their capacity to transport functional biomolecules that help counteract the cellular damage caused by cryopreservation. We then examine the types of cellular and molecular damages encountered during sperm cryopreservation and synthesize current evidence on the protective effects of EVs in this context. Particular attention is given to the mechanisms by which EVs may preserve sperm integrity, including membrane stabilization, antioxidant delivery, and modulation of signaling pathways. Despite encouraging findings, challenges remain, including the standardization of EVs isolation methods, optimal dosing, and delivery strategies. We also discuss the need for mechanism-of-action studies and multi-omics approaches to better understand EV-sperm interactions. Finally, future directions are outlined, including EVs engineering and clinical translation. Overall, EVs emerge as promising modulators in cryobiology, with potential to improve sperm preservation outcomes and fertility restoration strategies. This review offers an in-depth examination of EVs, covering the processes involved in their formation, various strategies employed for their isolation, and the techniques used to assess their properties. It also highlights their sources and functional significance in the male reproductive system.