FLOW CYTOMETRIC DETECTION OF SUBHAPLOID NUCLEI IN HUMAN SPERM AS A MEASURE OF DNA FRAGMENTATION AND APOPTOSIS

The use of assisted reproductive technologies (ARTs) is increasing worldwide. In order to predict the rate of pregnancy after ART the DNA fragmentation index (DFI) of ejaculated spermatocytes may be a better marker than conventional semen quality parameters. Spermatocytes with fragmented DNA are associated with apoptotic stages and are characterized by a low DNA content. The subhaploid nuclei of DNA-damaged spermatocytes can be easily detected by flow cytometry. We here analyzed the percentage of subhaploid nuclei of semen samples from 163 patients aged 26 to 74 years who consulted one of the ten centres for reproductive medicine which routinely send sperm samples to our laboratory in order to determine special sperm parameters. The percentage of subhaploid nuclei indicating the DFI of spermatocytes did not correlate with age and sperm volume, but inversely correlated with sperm concentration and the percentage of motile spermatocytes. This is in concordance with previous studies which demonstrated that DNA damage of spermatozoa correlates with conventional semen quality parameters. Since DNA-damaged spermatocytes are associated with an impaired outcome of assisted conception technologies, this method could help to monitor sperm quality of subfertile men after measures to increase sperm quality and to improve selection criteria of cryopreserved sperm samples in assisted reproduction medicine.