Sperm cryopreservation may be linked to DNA damage, possibly via oxidative stress. We compared the DNA damage, apoptosis levels, and oxidative stress in semen samples prior to and after slow cryopreservation and evaluated the relationship between these variables.METHODS:
Semen samples from 60 men who underwent assisted reproductive technology (ART) (experimental group) and 20 normozoospermic sperm donors (control group) were analyzed. DNA fragmentation, apoptosis levels, and plasma membrane lipid peroxidation/oxidative stress were evaluated using TUNEL, Annexin V-FITC Apoptosis Kit, and BODIPY/8OH-DG respectively. These variables were evaluated prior to slow cryopreservation and after thawing. Apoptosis (Annexin V), DNA fragmentation (TUNEL), and oxidative stress (BODIPY and 8OHDG) values were also compared between the group of men who underwent ART and the sperm donor group.RESULTS:
Annexin V, TUNEL, BODIPY, and 8OHDG values significantly increase after thawing (p<0.05). In the post-thawing group, the BODIPY and 8OHDG levels are significantly greater than the Annexin V level (p<0.05). Moreover, the sperm donor group had significantly lower Annexin V, TUNEL, and BODIPY and 8OHDG values than the group of men who underwent ART (p<0.05).CONCLUSION:
After slow-freezing thawing, there are higher levels of apoptosis, DNA fragmentation, and oxidative stress in semen samples than prior to cryopreservation. The slow freezing-thawing process induces sperm DNA damage via oxidative stress more so than apoptosis. Semen samples from men who underwent ART are more susceptible to oxidative stress and cell death than normozoospermic sperm donors.