S6 - Symposium 2

Extracellular vesicles of seminal plasma as modulators of sperm physiology

Cesari, Andreina ¹ - Armani, Tomas ¹ - Río, Sofía ² - Nicolli, Anabella ¹ - Perez-Martinez, Silvina ²

1)Instituto de Investigaciones Biológicas (CONICET-UNMdP)
2)Centro de Estudios Farmacológicos y Botánicos (CEFYBO)
Contacto: andreinacesari@gmail.com

Seminal plasma (SP) plays an important role in male reproductive physiology by providing signals that preserve sperm viability and regulate their capacitation timing. This fluid is composed by secretions from the epididymis and accessory glands. Traditionally, this regulation has been attributed exclusively to soluble proteins secreted through the classical pathway. However, recent evidence suggests that extracellular vesicles (EVs) present in SP may act as alternative or complementary mediators of sperm modulation, potentially carrying decapacitating factors and facilitating intercellular communication.
Our work explores whether decapacitation proteins are transported within SP-derived EVs (spEVs) and how these vesicles interact with sperm in vitro. We use human and ovine models to compare and characterize EV populations obtained by different methods -ultracentrifugation and size-exclusion chromatography (SEC). We found that spEVs are rapidly incorporated to live sperm following characteristic patterns, using fluorescent labeling. We also investigated whether these spEVs transport known decapacitation factors by Westernblot with different results in both species. In ram we demonstrated that proteins belonging to the BSP family (Binder of Sperm Proteins) are transferred from then spEVs to sperm cells, particularly by the fraction containing the smallest vesicles. Additionaly, we found that in both species spEVs modulate molecular signals of capacitation, such as tyrosine phosphorylation, acrosomal reaction, without affecting PKA activity, intracellular Ca2+ concentration or membrane potential. SpEVs also reduced progressive sperm motility.
This line of research shifts the focus from a purely soluble secretome to a vesicle-mediated mechanism of sperm regulation, with spEVs acting as vehicles for molecular signals that maintain sperm in a decapacitated state during their journey through the male reproductive tract. Our findings contribute to a better understanding of sperm physiology and have implications for male fertility diagnostics and assisted reproduction strategies.