E-Poster Presentation ESA-SRB-ANZBMS 2021

Assessment of the functional consequences of seminal fluid extracellular vesicle interactions with human spermatozoa (#583)

Cottrell T Tamessar 1 2 , Natalie A Trigg 1 2 , Amanda L Anderson 1 2 , Elizabeth G Bromfield 1 2 3 , Brett Nixon 1 2 , John E Schjenken 1 2
  1. Priority Research Centre for Reproductive Science and School of Environmental and Life Sciences, The University of Newcastle, Newcastle, NSW, Australia
  2. Pregnancy and Reproduction Program, Hunter Medical Research Institute, Newcastle, NSW, Australia
  3. Department of Biochemistry and Cell Biology and Faculty of Veterinary Medicine, Utrecht University, Utrecht, Netherlands

Seminal fluid contains one of the most abundant extracellular vesicle populations of any bodily fluid.  Seminal fluid extracellular vesicles (SFEVs) are proposed to perform a variety of functions including impacting sperm motility, capacitation, and the ability to undergo an acrosome reaction. However, variations in SFEV isolation and culture methods have led to inconsistencies in published data and hence their specific functions remain controversial. Here, we explored the functional consequences of SFEV interaction with human spermatozoa. Seminal plasma was collected from healthy donors and SFEVs were isolated in accordance with the Minimal Information for Studies of Extracellular Vesicles 2018 guidelines. Sperm:SFEV interactions were assessed in vitro at pH 5 and 7, mimicking the physiological pH spermatozoa encounter within the vagina and cervix/uterus, respectively. Sperm:SFEV docking capacity was assessed over a 1 hour co-culture period with biotin-labelled SFEVs. The functional consequences of sperm:SFEV interactions was assessed across 5 hours by Computer Assisted Sperm Analysis (motility) and immunocytochemistry (capacitation and acrosome reaction). SFEVs were observed to dock with spermatozoa and deposit biotinylated protein cargo (pH 5= 70.8%, pH 7= 88.3%) within 1-minute post incubation, with most labelling detected in the sperm tail. Sperm:SFEV binding did not further increase across the time course, nor did it vary according to pH. We also found no evidence that SFEVs altered sperm motility, capacitation status or the acrosome reaction. These findings demonstrate that while SFEVs have the capacity to interact with spermatozoa and deposit their cargo, under our co-culture conditions this interaction did not regulate sperm functional parameters. Altogether, these data raise the prospect that SFEVs may have alternate roles in the female reproductive tract. Given that extracellular vesicles are critical immune modulators in other physiological contexts, our future studies will focus on exploring the impact of SFEVs on the immune environment within the female reproductive tract.