Comparison of the effects of two methods of cryopreservation on testicular sperm DNA

Objective: To assess the effects of two methods of freezing on testicular sperm DNA from subjects with obstructive azoospermia and to compare these with samples of fresh and freeze-thawed testicular sperm from fertile men. Design: The Comet assay was used to determine the percentage of undamaged DNA in fresh testicular sperm, testicular sperm freeze-thawed in suspension and in a biopsy sample (men with obstructive azoospermia), and in fresh and freeze-than ed testicular sperm (fertile men). Setting: The Regional Fertility Center. Royal Maternity Hospital, Belfast, Northern Ireland, United Kingdom. Patient(s): Twelve males with obstructive azoospermia (normal testicular volume and hormone profiles) and nine fertile control subjects. Intervention(s): Trucut needle testicular biopsy under local anesthetic. Main Outcome Measure(s): Measurement of the percentage of undamaged DNA in fresh and freeze-thawed testicular sperm using the Comet assay. Result(s): No significant difference was found between the percentage of undamaged DNA of fresh testicular sperm and of both types of freeze-thawed testicular sperm. There was also no significant difference between the percentage of undamaged DNA in fresh or freeze-thawed testicular sperm from controls. Control ejaculated sperm DNA was significantly more damaged than testicular sperm DNA from control men. Conclusion(s): Cryopreservation of testicular sperm does not increase baseline levels of DNA damage. (Fertil Steril(R) 2000:74:450-3. (C) 2000 by American Society for Reproductive Medicine.).