Reactive oxygen species in cumulus cells inhibit the acrosome reaction in human sperm.

The present work aimed to analyze the effect of reactive oxygen species in cumulus cells on the acrosome reaction of human spermatozoa. For this purpose, we first evaluated the effect of reactive oxygen species in human sperm on the acrosome reaction, and the effect of reactive oxygen species in cumulus cells alone. Finally, we co-incubated human spermatozoa with human cumulus cells, previously exposed to different concentrations of hydrogen peroxide, and measured the percentage of reacting spermatozoa. Our results show an interaction effect between the levels of reactive oxygen species in human sperm and their capacitation state. High levels of reactive oxygen species induced the acrosome reaction in non-capacitated sperm, while reducing the percentage of acrosome reaction in capacitated sperm. Furthermore, our results show that, while non-stressed cumulus cells are capable of inducing the acrosome reaction, high levels of reactive oxygen species in cumulus cells hinder this capacity. These results suggest that, in the conditions used in this study, an oxidative environment in cumulus cells limits the number of sperm that react.