Freezing effect on post-thawed sperm characteristics especially sperm DNA integrity comparing between liquid nitrogen vapour and computerized program freezer.

ABSTRACT

The aim of the study was to evaluate the cryodamage effects on human sperm characteristics, especially on sperm DNA integrity, after 6 months of freezing comparing between liquid nitrogen vapour (LNV) and computerized program freezer (CPF). Forty normal semen samples were collected for semen analysis. Each sample was mixed with cryoprotective media and devided into 2 straws. The first straw was frozen with LNV and the second one with CPF. After 6 months of cryostorage, semen samples were thawed, and sperm chromatin integrity as well as sperm motility, morphology, vitality and cryosurvival rate were determined. Percentages of DNA damage were higher (p<0.01) following freezing with LNV than with CPF. Sperm vitality was greater (p<0.05) after CPF than after LNV, as well as cryosurvival rate (p<0.001). Post-thawed sperm motility was greater after CPF than after LNV, either in grade A (p<0.001) or in grade B (p<0.05). No significant difference was observed in the percentage of normal sperm morphology comparing the two freezing methods. The current study demonstrated post-thawed decrease in sperm DNA integrity as well as other sperm characteristics after freezing in both methods. The CPF significantly provided superior results in post-thawed sperm DNA integrity, sperm motility and vitality than LNV did. In case of 6 months of cryostorage, therefore, we recommend the computerized program freezer as a preference for sperm cryopreservation.