Potential adverse effect of semen processing on human sperm deoxyribonucleic acid integrity

Objective: To examine the effect of standard Percoll density-gradient centr ifugation on human sperm DNA denaturation. Design: Prospective, observational study. Setting: University-based infertility clinic. Patient(s): Twenty-five nonazoospermic men. Intervention(s): Semen samples (n = 25) were obtained from consecutively se en nonazoospermic men presenting for infertility evaluation. Samples were p rocessed by two-layer and four-layer Percoll density gradients. Sperm motil ity and sperm chromatin structure (evaluated by flow cytometry analysis of acridine orange-treated spermatozoa) were monitored before and after semen processing. Sperm chromatin integrity was expressed as the percentage of sp ermatozoa that demonstrated denatured DNA. Main Outcome Measure(s): Sperm motility and DNA integrity. Result(s): Mean sperm motility improved significantly after processing with two-layer and four-layer Percoll gradients compared with whole semen (54% and 57% motility versus 44% motility, respectively). In contrast, the perce ntage of sperm with denatured DNA increased after processing with two-layer and four-layer Percoll gradients compared with whole semen (34% and 32% ve rsus 18%, respectively). Conclusion(s): Our data demonstrate that the improvement seen in sperm moti lity after Percoll processing is not associated with a similar improvement in sperm DNA integrity. These data suggest that we reexamine current sperm processing techniques to minimize sperm DNA damage and the potential transm ission of genetic mutations in assisted reproductive cycles. (Fertil Steril (R) 1999;72:496-9. (C) 1999 by American Society for Reproductive Medicine.) .