Objective: To verify if the increase in sperm apoptotic DNA fragmentation during cryopreservation is greater in oligozoospermic patients than in normozoospermic controls.
Design: Controlled prospective study.
Setting: Patients in an academic research environment.
Patient(s): Forty-seven patients with oligozoospermia (concentration <10 x 10(6) sperm/mL) and 30 normozoospermic men.
Intervention(s): Sperm cryopreservation using a standard protocol with a test-yolk buffer, glycerol as the cryoprotectant.
Main outcome measure(s): Rate of apoptotic sperm DNA fragmentation as assessed by the terminal deoxynucleotidyl-mediated deoxyuridine triphosphate nickend labeling (TUNEL) assay, graded in apoptotic or nonapoptotic, before and after cryopreservation.
Result(s): An increase in apoptotic DNA fragmentation was observed in all the groups, regardless of sperm concentration. Normozoospermic men presented a smaller rate of apoptotic DNA fragmentation than oligozoospermic patients, both in pre- and postcryopreservation samples. The increase in DNA fragmentation was similar in both groups.
Conclusion(s): Cryopreservation induces apoptotic sperm DNA fragmentation in men, regardless of sperm concentration. Men with oligozoospermia present with higher precryopreservation and postcryopreservation apoptotic sperm DNA fragmentation. The increase in DNA fragmentation is similar in both groups.