title: Sperm swim-up techniques and DNA fragmentation.
abstract: BACKGROUND
  Swim-up techniques for sperm separation may have detrimental effects on sperm DNA. We wished to determine whether the normal swim-up method with centrifugation used in our laboratory, which involves a centrifugation step, was harmful to sperm compared with swim-up without centrifugation.
  
  
  METHODS
  Semen samples were obtained from patients undergoing IVF or andrology assessment. An aliquot was removed for fixation and subsequent DNA fragmentation determination. The remaining sample was divided into two equal parts, which were subjected to swim-up either with (normal swim-up) or without (direct-swim-up) centrifugation. Semen analysis was performed both before and after swim-up. DNA fragmentation, in spermatozoa previously fixed in 4% paraformaldehyde, was assessed by the terminal transferase-mediated DNA end-labelling procedure (TUNEL). The percentage of spermatozoa with DNA damage after each swim-up technique was compared with that in the original semen sample.
  
  
  RESULTS
  DNA damage was <5% in most samples. No significant change in DNA fragmentation was observed between the two swim-up procedures, although the 'normal' swim-up sample had significantly less DNA fragmentation than the pre-swim-up sample.
  
  
  CONCLUSIONS
  We conclude that our normal swim-up technique caused no more DNA damage to spermatozoa from normal semen samples than a direct swim-up technique that involved no centrifugation step.
authors.affiliation: Division of Reproductive Sciences, The Toronto General Hospital, The Samuel Lunenfeld Research Institute, University of Toronto, Toronto, Ontario, Canada. younglai@mcmaster.ca
authors.forename: E V
authors.initials: EV
authors.lastname: Younglai
authors.forename: D
authors.initials: D
authors.lastname: Holt
authors.forename: P
authors.initials: P
authors.lastname: Brown
authors.forename: A
authors.initials: A
authors.lastname: Jurisicova
authors.forename: R F
authors.initials: RF
authors.lastname: Casper
mesh_terms: D000328:Adult; D002498:Centrifugation; D046508:Culture Techniques; D053938:DNA Fragmentation; D006801:Humans; D008297:Male; D008875:Middle Aged; D009006:Monosomy; D009030:Mosaicism; D011003:Ploidies; D013081:Sperm Motility; D013094:Spermatozoa / Q000502:physiology*; D013997:Time Factors; D014314:Trisomy