Direct contact between boar spermatozoa and porcine oviductal epithelial cell (OEC) cultures is needed for optimal sperm survival in vitro.
Yeste M., Lloyd RE., Badia E., Briz M., Bonet S., Holt WV.
Oviductal epithelial cell (OEC) co-culture prolongs sperm viability and motility in vitro in a number of species including humans and horses. This study has sought to determine the effects of homologous OEC co-culture on boar sperm function. To determine whether the effects on spermatozoa were specifically caused by co-culture with or by OEC secretions, or by both factors together, a number of co-culture and cell-conditioned medium (CM) experiments were conducted. Firstly, Percoll-washed spermatozoa were co-cultured with OECs and pig kidney epithelial (LLC-PK1) cells, and in medium without cells. Secondly, Percoll-washed spermatozoa were incubated with CM derived from both OECs and LLC-PK1 cells and in unconditioned medium. A number of sperm function parameters were assessed after 5, 30, 60, 90, 120, and 180 min, and 24h of co-culturing or incubation with CM. Of all the sperm function parameters investigated, the percentage (%) viability data yielded the most interesting results. OECs (mean+/-S.E.M.; 31.2+/-1.10) were better than LLC-PK1 cells (24.3+/-0.93) at prolonging the viability of unbound spermatozoa after 24h of co-culturing (P<0.05). Also after 24h, the viability of spermatozoa bound to the OECs (77.6+/-1.83) was significantly higher than in the case of the LLC-PK1 cells (53.5+/-1.43; P<0.001). Other sperm function parameters, e.g., capacitation and motility, were also influenced by OEC co-culturing and incubation with CM, although to a lesser degree. In conclusion, porcine homologous OEC co-culture and CM incubation specifically affect sperm function. However, we propose that it is OEC co-culturing, rather than OEC-CM, that has the greater influence.