Sergey I. Moskovtsev

Sperm DNA Damage: Correlation to Severity of Semen Abnormalities

OBJECTIVES To analyze the relationship between DNA damage and standard semen parameters (SSP) in patients who present for fertility evaluation. Evaluation of male fertility includes assessment of the SSP and increasingly sperm DNA damage. However, the relationship between DNA damage and SSP remains controversial. METHODS Following Institutional Research Ethics Board approval, semen samples from 2586 unselected nonazoospermic patients were subjected to computer-assisted semen analysis and flow cytometry-based sperm DNA damage assessment expressed as the DNA fragmentation index. RESULTS Sperm DNA damage was significantly negatively correlated to sperm SSP (concentration, motility, and normal morphology) and positively correlated to patients age. DNA damage increased in association with the number of abnormalities in SSP. Patients with oligoasthenoteratozoospermia had significantly higher DNA damage and more frequent DNA damage over 30% compared with normozoospermic patients and patients with abnormalities in 1 or 2 SSP. CONCLUSIONS Our results indicate that DNA damage is significantly correlated to SSP as well as age. In addition, the degree of DNA damage increases with the number of abnormal parameters in a sample and is most severe in patients with oligoasthenoteratozoospermia. Complex and possibly age-related mechanisms of DNA damage in human spermatozoa may be responsible for the strong relationship between SSP and DNA fragmentation index.

Testicular spermatozoa have statistically significantly lower DNA damage compared with ejaculated spermatozoa in patients with unsuccessful oral antioxidant treatment

OBJECTIVE To compare DNA damage in ejaculated and testicular spermatozoa in patients with previously unsuccessful oral antioxidant treatment. DESIGN Prospective clinical study. SETTING University-affiliated teaching hospital. PATIENT(S) Twelve men with persistently high sperm DNA damage. INTERVENTION(S) Evaluation of DNA damage of ejaculated and testicular spermatozoa by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling (TUNEL) assay. MAIN OUTCOME MEASURE(S) The DNA damage of ejaculated spermatozoa compared with that of testicular spermatozoa, both samples collected on the day of intracytoplasmic sperm injection. RESULT(S) Ejaculated spermatozoa showed a threefold higher DNA damage when compared with testicular samples (39.7% +/- 14.8 vs. 13.3% +/- 7.3). CONCLUSION(S) Our results indicated that in patients with previously unsuccessful oral antioxidant treatment the retrieved testicular spermatozoa had a lower degree of DNA damage compared with ejaculated sperm collected on the same day.

Disruption of telomere-telomere interactions associated with DNA damage in human spermatozoa.

Telomeres play a fundamental role in the organization of the sperm nucleus resulting in the looped chromosome configuration and non-random positioning of chromosomes. Telomeres localize in the nuclear periphery and interact dynamically by forming dimers and tetramers. The purpose of this study was to evaluate the relationship of telomere interactions to DNA damage, a factor known to adversely influence male fertility. Telomeres were localized by fluorescence in situ hybridization (FISH) using human chromosome pan-telomeric probe in ten samples with low and ten samples with high sperm DNA damage. The samples with a low DNA fragmentation index (DFI) had a mean number of telomere signals of 21.7±1.9 compared to a mean of 26.5±3.4 signals in the samples with a high DFI (p<.005). The percentage of cells with a typical telomere distribution of ≤23 telomere-telomere dimers was observed in 70.8%±15.6 samples with a low DFI compared to 44.2%±22.4 in samples with a high DFI (p<.05). These results suggest that sperm DNA damage is associated with disruption of the normal telomere–telomere interactions leading to possible loss of the looped chromosome configuration. Improperly packed and organized sperm chromatin might have a high probability of disrupting the extremely structured sequence of sperm chromosome deposition, activation, and processing by the oocyte at the time of fertilization. These results might provide additional information on the nature of sperm DNA damage and the role of such damage on fertilization and development of the zygote.

Frequency and severity of sperm DNA damage in patients with confirmed cases of male infertility of different aetiologies

Men with high sperm DNA damage have a reduced fertility potential. Correlation of specific clinical factors to the degree of sperm DNA damage remains unclear. This retrospective study evaluated the frequency and severity of sperm DNA damage in men with different aetiologies of male factor infertility. Patients with male factor infertility (n=288) underwent flow cytometry-based sperm DNA damage assessment and results were correlated with the major aetiologies of male infertility: varicocele, bacteriospermia and idiopathic infertility. Sperm DNA damage was significantly correlated to the patients age, sperm motility, normal morphology and vitality (P < 0.001). High sperm DNA damage (30%) was most frequently found in the group with bacteriospermia (48%), compared with 30% of the men with varicoceles and 22% of the men with idiopathic infertility (P < 0.02). While some tendency was observed for a correlation of increasing sperm DNA damage in patients with grade III and bilateral varicoceles, this difference did not reach statistical significance. The data support the importance of proper physical and laboratory investigations of the fertility status in men to correctly diagnose and treat male infertility.

Sperm survival: relationship to age-related sperm DNA integrity in infertile men.

The purpose of our study was to evaluate the effect of age and sperm DNA integrity on sperm survival. Semen samples from fifty six unselected patients undergoing infertility evaluation were assessed in terms of standard semen parameters, DNA integrity, and sperm survival after 6–24 h of incubation. Prolonged incubation of density gradient selected sperm adversely effects sperm survival in older patients and patients with extensive sperm DNA damage. Immediate preparation of such samples prior to use for assisted reproductive technology (ART) may overcome the negative effect of extended incubation.

Aneuploidy rates in ejaculated and testicular spermatozoa in patients with high sperm dna damage

ANEUPLOIDY RATES IN EJACULATED AND TESTICULAR SPERMATOZOA IN PATIENTS WITH HIGH SPERM DNA DAMAGE. S. I. Moskovtsev, N. Alladin, K. C. Lo, K. Jarvi, J. B. M. Mullen, C. L. Librach. CReATe Fertility Center, Toronto, ON, Canada; Department of Pathology and Laboratory Medicine, Mount Sinai Hospital, Toronto, ON, Canada; Division of Urology, Department of Surgery, Mount Sinai Hospital, Toronto, ON, Canada; Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynaecology, Sunnybrook Health Sciences Centre, Toronto, ON, Canada.