Porcine sperm bind to an oviduct glycan coupled to glass surfaces as a model of sperm interaction with the oviduct

During transport through the oviduct, sperm interact with epithelial cells by attaching to specific glycans, a mechanism believed to select sperm and prolong their viability. An in vitro model of sperm-oviduct interactions was developed, consisting of a glass surface (either a slide or a coverslip) to which an oviduct glycan (sulfated Lewis X trisaccharide; suLe^X) is coupled. The ability of porcine sperm to attach to suLe^X-surfaces and detach in response to progesterone and mature cumulus-oocyte complexes (COCs) was validated. The suLe^X-coverslip was adapted for in vitro fertilization (IVF), termed glycan-IVF, by allowing porcine sperm to first bind suLe^X before transferring mature COCs. The glycan-IVF method produced a percentage of fertilized oocytes comparable to that of conventional IVF (75.1 vs. 72.0%). Finally, the ability of the suLe^X-coverslip to maintain sperm fertilizing ability over time was assessed. After 24 h of incubation, fertilization by sperm bound to the suLe^X-coverslip was sustained, compared to sperm with unmodified coverslips (12.0 vs. 1.0%, p < 0.05). Furthermore, the percentage of polyspermic zygotes was reduced in the suLe^X-coverslip method (17.7 vs. 41.3%, p < 0.05). This study validated an in vitro model for studying sperm-oviduct interactions, with potential applications in assisted reproductive technologies.