title: Cryopreservation of fractionated, highly motile human spermatozoa: effect on membrane phosphatidylserine externalization and lipid peroxidation.
abstract: BACKGROUND
  This study investigated lipid peroxidation (LPO) and membrane integrity following cryopreservation-thawing.
  
  
  METHODS
  Infertile men (study group) and donors (control group) were examined. Purified populations of highly motile spermatozoa were cryopreserved using TEST-yolk buffer and glycerol (TYB-G) followed by quick thaw. LPO was measured by a spectrophotometric assay, with and without a ferrous ion promoter. Annexin V binding was used to assess membrane translocation of phosphatidylserine (PS).
  
  
  RESULTS
  Pre-freeze LPO was significantly higher in the study than in the control group (P = 0.03). In both groups, LPO measurements after thawing were significantly higher than the pre-freeze samples not exposed to TYB-G (P = 0.002 and P = 0.001 respectively). However, when the pre-freeze samples with TYB-G were compared with the post-thaw samples (all exposed to TYB-G), these differences were not significant. There was a significant increase in PS externalization following cryopreservation in both groups (P = 0.02 and P = 0.003 respectively). In donors, pre-freeze LPO concentrations had a significant positive correlation with thawed spermatozoa depicting PS externalization (r = 0.77, P = 0.04).
  
  
  CONCLUSIONS
  Although patients had higher basal LPO than donors, LPO did not differ between fresh and cryopreserved-thawed fractionated motile spermatozoa. Freezing-thawing was associated with translocation of PS to the external membrane leaflet.
authors.affiliation: The Jones Institute for Reproductive Medicine, Department of Obstetrics and Gynecology, Eastern Virginia Medical School, Norfolk, VA 23507, USA.
authors.forename: A
authors.initials: A
authors.lastname: Schuffner
authors.forename: M
authors.initials: M
authors.lastname: Morshedi
authors.forename: S
authors.initials: S
authors.lastname: Oehninger
mesh_terms: D001692:Biological Transport; D002458:Cell Fractionation; D002462:Cell Membrane / Q000378:metabolism; D015925:Cryopreservation; D006801:Humans; D007248:Infertility, Male / Q000378:metabolism; D008054:Lipid Peroxides / Q000378:metabolism*; D008297:Male; D010718:Phosphatidylserines / Q000378:metabolism*; D012016:Reference Values; D013081:Sperm Motility; D013094:Spermatozoa / Q000502:physiology*; D014019:Tissue Donors
chemical_list: D008054:Lipid Peroxides; D010718:Phosphatidylserines