title: DNA integrity and motility of human spermatozoa after standard slow freezing versus cryoprotectant-free vitrification.
abstract: BACKGROUND
  In contrast to the technique of conventional freezing, the vitrification of spermatozoa requires high cooling rates (720 000 degrees K/min), which could be damaging for spermatozoa. The aim of our study was to compare slowly frozen and vitrified spermatozoa in terms of their post-thaw DNA integrity and motility.
  
  
  METHODS
  Semen samples were prepared according to the routine swim-up technique and divided into aliquots for comparison of fresh, conventionally frozen and vitrified spermatozoa from the same ejaculate in the presence or absence of cryoprotectants. Spermatozoa motility and DNA integrity were determined.
  
  
  RESULTS
  The motility of spermatozoa conventionally (slowly) frozen with a cryoprotectant was similar to that recorded for spermatozoa vitrified in the absence of cryoprotectant (47 versus 52%). The DNA integrity was unaffected by the cryopreservation method or presence of cryoprotectants.
  
  
  CONCLUSIONS
  The vitrification of human spermatozoa in the absence of conventional cryoprotectants is indeed feasible. The DNA integrity of vitrified sperm is comparable with that shown by standard slow-frozen/thawed spermatozoa, yet the method is quick and simple and does not require special cryobiological equipment.
authors.affiliation: Department of Obstetrics and Gynecology, University of Cologne, Kerpener Str. 34, D-50931 Cologne, Germany. jeniaisachenko@yahoo.de
authors.forename: E
authors.initials: E
authors.lastname: Isachenko
authors.forename: V
authors.initials: V
authors.lastname: Isachenko
authors.forename: I I
authors.initials: II
authors.lastname: Katkov
authors.forename: G
authors.initials: G
authors.lastname: Rahimi
authors.forename: T
authors.initials: T
authors.lastname: Schöndorf
authors.forename: P
authors.initials: P
authors.lastname: Mallmann
authors.forename: S
authors.initials: S
authors.lastname: Dessole
authors.forename: F
authors.initials: F
authors.lastname: Nawroth
mesh_terms: D015925:Cryopreservation / Q000379:methods* / Q000592:standards; D003451:Cryoprotective Agents; D004249:DNA Damage; D005240:Feasibility Studies; D006801:Humans; D008297:Male; D012662:Semen Preservation; D013081:Sperm Motility; D013094:Spermatozoa / Q000502:physiology*; D013997:Time Factors
chemical_list: D003451:Cryoprotective Agents