DNA integrity and motility of human spermatozoa after standard slow freezing versus cryoprotectant-free vitrification
E. Isachenko1,5, V. Isachenko2, I.I. Katkov3, G. Rahimi1, T. Schöndorf1, P. Mallmann1, S. Dessole4 and F. Nawroth1
1 Department of Obstetrics and Gynecology, University of Cologne, Kerpener Str. 34, D-50931 Cologne, 2 Department of Gynecological Endocrinology and Reproductive Medicine, University of Bonn, Bonn, Germany, 3 Cancer Center, University of California at San Diego, La Jolla, CA, USA and 4 Department of Obstetrics and Gynecology, University of Sassari, Sassari, Italy
5 To whom correspondence should be addressed. e-mail: [email protected]
BACKGROUND: In contrast to the technique of conventional freezing, the vitrification of spermatozoa requires high cooling rates (720 000°K/min), which could be damaging for spermatozoa. The aim of our study was to compare slowly frozen and vitrified spermatozoa in terms of their post-thaw DNA integrity and motility. METHODS: Semen samples were prepared according to the routine swim-up technique and divided into aliquots for comparison of fresh, conventionally frozen and vitrified spermatozoa from the same ejaculate in the presence or absence of cryoprotectants. Spermatozoa motility and DNA integrity were determined. RESULTS: The motility of spermatozoa conventionally (slowly) frozen with a cryoprotectant was similar to that recorded for spermatozoa vitrified in the absence of cryoprotectant (47 versus 52%). The DNA integrity was unaffected by the cryopreservation method or presence of cryoprotectants. CONCLUSION: The vitrification of human spermatozoa in the absence of conventional cryoprotectants is indeed feasible. The DNA integrity of vitrified sperm is comparable with that shown by standard slow-frozen/thawed spermatozoa, yet the method is quick and simple and does not require special cryobiological equipment.
Key words: comet assay/cryopreservation/human/sperm DNA/vitrification
Source: Human Reproduction, Vol. 19, No. 4, 932-939, April 2004.