title: Cryopreservation of human semen and prepared sperm: effects on motility parameters and DNA integrity.
abstract: OBJECTIVE
  To investigate effects of cryopreservation on sperm motility and DNA integrity.
  
  
  METHODS
  Pre-cryopreservation and post-cryopreservation analysis of motility and DNA integrity of semen and prepared sperm samples.
  
  
  METHODS
  A hospital andrology laboratory.
  
  
  METHODS
  Forty men attending the Regional Fertility Centre, Belfast, Northern Ireland.
  
  
  METHODS
  Each sample was divided, and an aliquot was frozen unprepared. Remaining aliquots were prepared by Percoll density centrifugation (95.0:47.5) or direct swim-up procedure and divided into aliquots to allow direct comparison of fresh and frozen semen and prepared sperm (frozen with or without the addition of seminal plasma) from the same ejaculate. Samples were frozen by static-phase vapor cooling and being plunged into liquid nitrogen. Thawing was carried out at room temperature.
  
  
  METHODS
  Sperm DNA integrity was determined using a modified alkaline single cell gel electrophoresis (comet) assay, and motility was determined using computer-assisted semen analysis.
  
  
  RESULTS
  Sperm frozen unprepared in seminal fluid appeared more resistant to freezing damage than frozen prepared sperm. Further improvements can be achieved by selecting out the subpopulation of sperm with best motility and DNA integrity and freezing these sperm in seminal plasma, making this the optimal procedure.
  
  
  CONCLUSIONS
  Freezing sperm in seminal plasma improves postthaw motility and DNA integrity.
authors.affiliation: Department of Obstetrics and Gynaecology, The Queen's University of Belfast, Northern Ireland. e.donnelly@qub.ac.uk
authors.forename: E T
authors.initials: ET
authors.lastname: Donnelly
authors.forename: N
authors.initials: N
authors.lastname: McClure
authors.forename: S E
authors.initials: SE
authors.lastname: Lewis
mesh_terms: D015925:Cryopreservation; D004249:DNA Damage; D006801:Humans; D008297:Male; D012661:Semen; D013077:Sperm Head / Q000502:physiology; D013081:Sperm Motility; D013094:Spermatozoa / Q000502:physiology*; D013997:Time Factors