Influence of initial semen quality on the integrity of human sperm DNA following semen processing.

OBJECTIVE

To examine and compare the effects of density-gradient centrifugation on the integrity of sperm DNA from the semen of both fertile and infertile men.

DESIGN

Prospective, observational study.

SETTING

University infertility clinic.

PATIENTS

Forty-four nonazoospermic, infertile men and nine fertile controls.

INTERVENTIONS

Semen samples were processed by density-gradient centrifugation. Sperm motility and sperm chromatin structure (evaluated by flow cytometry analysis of acridine orange-treated spermatozoa) were monitored before and after semen was processed.

MAIN OUTCOME MEASURES

Sperm motility and DNA integrity.

RESULTS

Following density-gradient centrifugation, mean sperm motility (+/-SEM) improved significantly compared to whole semen in samples from fertile and infertile men, respectively (71 +/- 6 vs. 49 +/- 7% and 56 +/- 3 vs. 44 +/- 3%, P<0.05). However, the percentage of sperm with denatured DNA increased compared to whole semen after processing of samples from infertile (25 +/- 3 vs. 15 +/- 2%, P<0. 01) but not fertile men (9 +/- 3 vs. 8 +/- 2%, P>0.05).

CONCLUSIONS

Our data indicate that the potential detrimental effect of density-gradient centrifugation on sperm DNA integrity is related to the initial semen quality. These data urge us to examine our current sperm-processing techniques to minimize sperm DNA damage.