The DNA integrity of cryopreserved spermatozoa separated for use in assisted reproductive technology is unaffected by the type of cryoprotectant used but is related to the DNA integrity of the fresh separated preparation.
OBJECTIVE
To investigate and compare seven different commercially available cryoprotectant media in terms of the DNA integrity of spermatozoa recovered after cryopreservation and separation using density gradient centrifugation (DGC).


METHODS
A prospective clinical study.


METHODS
Tertiary care fertility clinic.


METHODS
Three hundred twenty men presenting for infertility investigations.


METHODS
Each sample was randomly assigned to one of seven commercially available cryoprotectants or to no cryoprotectant.


METHODS
Percentage sperm DNA fragmentation after cryopreservation and preparation using DGC.


RESULTS
The mean percentage fragmentation was significantly higher post-thaw and post-DGC; however, some patients (26.3%) demonstrated a lower percentage fragmentation post-thaw. No single cryoprotectant was identified as the best at preserving DNA integrity. The difference in fragmentation after thawing and DGC was found to be highly dependent on the prefreeze fragmentation. Motility was also significantly correlated with the difference in fragmentation post-thaw (r = -0.161).


CONCLUSIONS
Neither the presence nor type of cryoprotectant affects the DNA integrity of spermatozoa after cryopreservation and DGC. Individuals with lower prefreeze fragmentation in DGC-prepared spermatozoa have larger increases in fragmentation and are less likely to exhibit lower levels of fragmentation post-thaw. The reverse effect observed in those with higher prefreeze fragmentation gives rise to a possible novel method of reducing fragmentation in sperm used for assisted reproductive technology treatment cycles without the need for testicular sperm retrievals.
Thomson
Laura Kelly
LK
Fertility First, Hurstville, Australia. Electronic address: lthomson@fertilityfirst.com.au.
Fleming
Steven Denis
SD
Department of Obstetrics and Gynecology, Westmead Hospital, University of Sydney, Sydney, Australia.
Schulke
Lauren
L
Fertility First, Hurstville, Australia.
Barone
Katrina
K
Fertility First, Hurstville, Australia.
Zieschang
Julie-Anne
JA
Fertility First, Hurstville, Australia.
Clark
Anne Melton
AM
Fertility First, Hurstville, Australia.
D000328:Adult; D000375:Aging / Q000502:physiology; D002469:Cell Separation / Q000379:methods; D002499:Centrifugation, Density Gradient; D015925:Cryopreservation / Q000379:methods*; D003451:Cryoprotective Agents / Q000009:adverse effects / Q000494:pharmacology*; D004247:DNA / Q000187:drug effects* / Q000502:physiology*; D053938:DNA Fragmentation / Q000187:drug effects; D006801:Humans; D007248:Infertility, Male / Q000628:therapy; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D027724:Reproductive Techniques, Assisted; D012661:Semen / Q000502:physiology; D012746:Sexual Abstinence / Q000502:physiology; D013081:Sperm Motility / Q000187:drug effects; D013094:Spermatozoa / Q000187:drug effects* / Q000502:physiology*
D003451:Cryoprotective Agents; D004247:DNA