Frequent structural chromosome aberrations in immotile human sperm exposed to culture media.

BACKGROUND The influence of culture media or centrifugation on chromosomes of immotile human sperm was examined using ICSI into mouse oocytes. METHODS In experiment 1, immotile and motile human sperm retrieved directly from ejaculates were injected into mouse oocytes. In experiment 2, immotile human sperm were exposed to seminal plasma or one of four kinds of culture media (HEPES-BWW, modified-BWW, modified-human tubal fluid (HTF) and Dulbecco's phosphate-buffered saline) for 1.5-2.5 h at 18 degrees C in air before microinjection. In experiment 3, immotile human sperm were centrifuged along with HEPES-BWW before microinjection. In experiment 4, frozen-thawed immotile human sperm washed with seminal plasma or HEPES-BWW were injected into mouse oocytes. The hybrid oocytes were prepared for chromosome slides at first cleavage metaphase and were then examined cytogenetically. RESULTS In experiment 1, there was no significant difference in the incidences of structural chromosome aberrations between motile and immotile sperm (4.3% versus 5.8%). In experiment 2, culture media caused more frequent structural chromosome aberrations (14.3-32.6%) in immotile sperm than did seminal plasma (5.4%). In experiment 3, structural chromosome aberrations were found in 48.1% of the centrifuged immotile sperm, and a live/dead sperm viability test intimated that the aberrant sperm were probably dead. In experiment 4, the incidence of structural chromosome aberrations in frozen-thawed immotile sperm was significantly higher in HEPES-BWW (62.2%) than in seminal plasma (17.2%). CONCLUSIONS The results indicate that immotile sperm do not have significantly more DNA lesions than motile sperm, although DNA of immotile sperm appears to be vulnerable to damage caused by different culture media.