Cubilla, MA; Franchi, NA and Giojalas, LC. Does the uterus milieu contribute to prepare human sperm for fertilizing the oocyte? , Holderness, USA. 2013.

CUBILLA M; FRANCHI AN; GIOJALAS LC

Congreso; Gordon Research Conference on Fertilization and Activation of Development; 2013

Background. In order to fertilize the oocyte, mammalian spermatozoa must undergo a series of biochemical and physical changes collectively called capacitation. It is well known that sperm capacitation takes place upon interaction with the oviduct epithelium. However, during the transit along the uterus spermatozoa also are in contact with the secretions of different cell types, where some proteins secreted by endometrial cells have been reported to stimulate sperm preparation for fertilization. Objective. To evaluate whether conditioned media (CM) from endometrial epithelial cells affects human sperm physiology. Methodology/Design. After seminal plasma removal, spermatozoa were incubated with conditioned media (CM) obtained from endometrial epithelial cells (Ishikawa cell line). Sperm viability, motility parameters and percentage of Ca2-ionophore-induced acrosome reaction were assessed at different time points. In parallel, sperm protein tyrosine phosphorylation (PY) was evaluated as a different approach to verify sperm capacitation. Results. The percentage of induced acrosome reacted sperm significantly increased with the incubation time in the cells treated with CM, without affecting sperm viability and motility, results that were confirmed by PY. Interestingly, when spermatozoa were shortly incubated for 15 min in the presence of CM, then washed and further incubated for 0, 2 or 4 h in HAM medium the level of induced acrosome reacted sperm was similar to that observed after continuous 4 h incubation with CM. We further investigated a candidate endometrial protein that might be responsible for priming spermatozoa for the acrosome reaction. Thus, spermatozoa incubated in CM pre-treated with anti-MFGE8 antibody showed a significant decrease in the level of induced acrosome reaction. Conclusions. These preliminary results suggest that: (1) CM from endometrial epithelial cells prime spermatozoa for the induced acrosome reaction without affecting sperm viability and motility; (2) a similar effect is caused by a short exposition to CM; (3) the priming effect of CM is suppressed when CM is pre-incubated with a specific antibody against MFGE8. As a whole, these results suggest that the sperm transit along the uterus may contribute to the sperm preparation for fertilizing the oocyte.