Extracellular vesicles in porcine seminal plasma maintain sperm function by reducing Lyso-PC

Seminal plasma (SP) exosomes are membrane vesicles with 30−120 nm diameter, which have been shown to regulate the physiological processes in sperm cells. However, the mechanism through which SP extracellular vesicles (EVs) maintain sperm function remains unclear. To explore the mechanism of EVs in sperm preservation, different EV concentrations (EV-0, EV-1, EV-4, EV-8, EV-16) were added to semen liquid preservation solution. Sperm motility was detected via computer-assisted sperm analysis systems, plasma membrane integrity was assessed using SYBR-14 and propidium iodide staining, and total antioxidant capacity and lipid oxidation levels were evaluated after 0, 2, 4, 6 days of liquid-storage at 17°C. Differences in sperm metabolites between the EV-0 and EV-8 groups stored for 4 days, were analyzed using untargeted metabolomics [liquid chromatography with tandem mass spectrometry (LC-MS/MS)]. Moreover, mitochondrial reactive oxygen species (mtROS) levels were assessed when sperm incubated with EV-0 and EV-8 during 0, 2, 4, 6 days, and embryonic development were assessed when sperm incubated with EV-0 and EV-8 stored for 4 days at 17°C. Our data showed that compared to EV-0, sperm motility and plasma membrane integrity, antioxidant capacity, lipid oxidation levels and cleavage rates were significantly increased in the EV-8 group (P < 0.05), lysophosphatidylcholine (Lyso-PC) metabolisma and mtROS levels were significantly reduced in the EV-8 group (P < 0.05). In conclusion, SP EVs inhibit the premature increase in Lyso-PC, exert antioxidant effects on mtROS, and preserve sperm's ability to fuse with oocytes.