Effects of cryopreservation and density-gradient washing on phospholipase C zeta concentrations in human spermatozoa

Cryopreservation and density-gradient washing (DGW) are routinely used in infertility treatment. This study used quantitative immunofluorescence analysis to report how these techniques affect concentrations of the oocyte activation factor, phospholipase C zeta (PLC zeta) in spermatozoa from fertile men. DGW significantly elevated the proportion of spermatozoa in which PLC zeta could be detected (by 25-81%; P < 0.0001). In contrast, in four donors, cryopreservation significantly reduced PLC zeta concentrations (by 20-56%; P < 0.0001). These findings indicate that while DGW positively selects spermatozoa with detectable PLC zeta, cryopreservation has significant detrimental effects upon PLC zeta concentrations. Since reduced PLC zeta concentrations have been implicated in deficient oocyte activation and infertility, further study is highly warranted. (C) 2011, Reproductive Healthcare Ltd. Published by Elsevier Ltd. All rights reserved.