Reduced senescence and retained nuclear DNA integrity in human spermatozoa prepared by density gradient centrifugation

Purpose: To investigate whether removal of extraneous cells and immotile spermatozoa from a sperm preparation by density gradient centrifugation could help to maintain normal spermatozoa in a viable state and retain their deoxyribonucleic acid integrity. Methods: Sperm motility was assessed on a daily basis in aliquots of neat semen, extended semen, and spermatozoa prepared on a PureSperm. density gradient. At the same time, aliquots of each sperm sample were preserved for TUNEL assay and nick translation. Results: Spermatozoa prepared using density gradient centrifugation survived three times as long as spermatozoa in neat semen or in extended semen. Both deoxyribonucleic acid integrity and sperm motility were retained in the gradient preparations. Conclusions: Preparing spermatozoa by density gradient centrifugation is advantageous in prolonging sperm survival and maintaining deoxyribonucleic acid integrity, presumably by removing sources of reactive oxygen species. Stored spermatozoa could be used for a second attempt at fertilization if oocyte immaturity was suspected.