A simple comet assay for archived sperm correlates DNA fragmentation to reduced hyperactivation and penetration of zona-free hamster oocytes

Objective: To correlate sperm variables with sperm DNA fragmentation, as as sessed by using a modified alkaline comet assay for sperm smears. Design: The comet assay was adapted for fixed sperm smears (59 cases), and the level of DNA fragmentation was determined. Setting: Clinical and academic research environment. Patient(s): 59 patients undergoing fertility treatment. Intervention(s): Sperm samples leftover from IVF procedures were fixed and processed for the comet assay. Main Outcome Measure(s): Sperm head DNA density and sperm variables. Result(s): A correlation was observed between increased sperm head DNA frag mentation and decreased penetration of zona-free hamster oocytes. Heat-indu ced hyperactive motility decreased as DNA fragmentation increased. The DNA fragmentation did not correlate with percentages of intact acrosome, normal ity, maturity, and strict normal morphology. Conclusion(s): The advantages of the comet assay for archived cells include simplicity, low intraassay coefficient of variation, and low performance c ost; in addition, DNA analysis can be carried out at leisure. Low DNA damag e was associated with higher hyperactivation and oocyte penetration, sugges ting that failed fertilization was linked to compromised DNA integrity in t he sperm. Exploration of compounds to repair damaged DNA is warranted. (C) 2001 by American Society for Reproductive Medicine.