Cryopreservation-thawing of fractionated human spermatozoa and plasma membrane translocation of phosphatidylserine

Objective: [1] To evaluate sperm membrane damage during cryopreservation-th awing by the assessment of phosphatidylserine (PS) translocation and [2] to examine the relationship between reactive oxygen species (ROS) and cryopre servation-related alterations. Design: Prospective cohort study. Setting: University-based center. Patient(s): Men consulting for infertility and fertile donors (controls). Intervention(s): Semen processing was performed by density gradient separat ion followed by cryopreservation acid thawing. Main Outcome Measure(s): Membrane PS translocation was evaluated with annex in V binding, generation of ROS was detected by chemiluminescence, and moti on parameters were assessed by computer analysis. Result(s): Annexin V binding was detected in the prefreeze fractions with h igh and low sperm motility. In the patient group, there were significantly higher postthaw levels of annexin V binding in both fractions when compared with prefreezing values. However, such induction of PS translocation was s ignificantly higher in the fractions with high sperm motility. Significantl y higher ROS levels were detected in prefreeze samples of the fractions wit h low sperm motility. Conclusion(s): In the population of men studied, [1] cryopreservation-thawi ng was associated with induction of membrane PS translocation; [2] postthaw ROS levels were lower than before freezing; and [3] neither annexin V bind ing results nor the generation of ROS were able to accurately predict sperm cryosurvival rates. (C) 2001 by American Society for Reproductive Medicine .