ABSTRACT:The frequency of sperm cells with fragmented DNA was studied in a group of 18 infertile patients with varicocele and compared with those obtained in a group of 51 normozoospermic patients, 103 patients with abnormal standard semen parameters, and 22 fertile men. The spermatozoa were processed to discriminate different levels of DNA fragmentation using the Halospermா kit, an improved Sperm Chromatin Dispersion (SCD) test. In this technique, after an acid incubation and subsequent lysis, those sperm cells without DNA fragmentation show big or medium-sized halos of dispersion of DNA loops from the central nuclear core. Otherwise, those spermatozoa containing fragmented DNA either show a small halo, exhibit no halo with solid staining of the core, or show no halo and irregular or faint stain of the remaining core. The latter, that is, degraded type, corresponds to a much higher level of DNA-nuclear damage. The varicocele patients showed 32.4% Ϯ 22.3% of spermatozoa with fragmented DNA, significantly different from the group of fertile subjects (12.6% Ϯ 5.0%). Nevertheless, this was not different from that of normozoospermic patients (31.3% Ϯ 16.6%) (P ϭ .83) and with abnormal semen parameters (36.6% Ϯ 15.5%) (P ϭ .31). No significant differences were found between the normozoospermic patients and the patients with abnormal semen parameters. Strikingly, the proportion of the degraded cells in the total of sperm cells with fragmented DNA was 1 out of 4.2 (23.9% Ϯ 12.9%) in the case of varicocele patients, whereas it was 1 out of 8.2 to 9.7 in the normozoospermic patients (11.1% Ϯ 9.9%) in the patients with abnormal sperm parameters (12.2% Ϯ 8.3%) and in the fertile group (10.3% Ϯ 7.2%). Thus, whereas no differences in the percentage of sperm cells with fragmented DNA were evident with respect to other infertile patients, individuals with varicocele exhibit a higher yield of sperm cells with the greatest nuclear DNA damage level in the population with fragmented DNA. This finding illustrates the value of assessing different patterns of DNA-nuclear damage within each sperm cell and the particular ability of the Halospermா kit to reveal them.Key words: Human sperm, DNA fragmentation. J Androl 2006;27:106-111 V aricocele, that is, dilation of the pampiniform venous plexus above and around the testicle, occurs in approximately 15% to 20% of the general male population, especially in adolescents. Varicocele occurs in 19% to 41% of men seeking infertility treatment and in around 80% of men with secondary infertility. Thus, this anatomical abnormality is perhaps one of the most common causes of poor sperm production and decreased semen quality.
Previous studies suggest that sperm DNA fragmentation may be associated with aneuploidy. However, currently available tests have not made it possible to simultaneously perform DNA fragmentation and chromosomal analyses on the same sperm cell. The recently introduced sperm chromatin dispersion (SCD) test allows users to determine this relationship. Semen samples from 16 males, including 4 fertile donors, 7 normozoospermic, 3 teratozoospermic, 1 asthenozoospermic, and 1 oligoasthenoteratozoospermic, were processed for DNA fragmentation analysis by the SCD test using the Halosperm kit. Three-color fluorescence in situ hybridization (FISH) was performed on SCD-processed slides to determine aneuploidy for chromosomes X, Y, and 18. Spermatozoa with DNA fragmentation showed a 4.4 6 1.9-fold increase in diploidy rate and a 5.9 6 3.5-fold increase in disomy rate compared to spermatozoa without DNA fragmentation. The overall aneuploidy rate was 4.6 6 2.0-fold higher in sperm with fragmented DNA (Wilcoxon rank test: P , .001 in the 3 comparisons). A higher frequency of DNA fragmentation was found in sperm cells containing sex chromosome aneuploidies originated in both first and second meiotic divisions. The observed increase in aneuploidy rate in sperm with fragmented DNA may suggest that the occurrence of aneuploidy during sperm maturation may lead to sperm DNA fragmentation as part of a genomic screening mechanism developed to genetically inactivate sperm with a defective genomic makeup.
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