Oxidative stress in follicular fluid of young women with low response compared with fertile oocyte donors.

The aim of this study was to determine the concentrations of oxidative stress markers, antioxidant enzymes and cytokines in the follicular fluid of young women with low response in ovarian stimulation cycles compared with high responders and fertile oocyte donors of the same age, to assess the impact of oxidative stress on ovarian reserve. The activity of follicular fluid antioxidant enzymes glutathione transferase, glutathione reductase and glutathione peroxidase was significantly lower in young women with reduced ovarian reserve compared with that in high responders and oocyte donors. Follicular fluid concentrations of oxidative stress marker malondialdehyde combined with 4-hydroxyalkenals and nitric oxide were higher in low responders than in high responders and oocyte donors. Significant differences between low responders and donors in concentrations of IL-2, IL-6, IL-8 and vascular endothelial growth factor were observed, with higher concentrations in low responders. However, IL-10 concentration was lower in low responders than in high responders and donors. No significant differences were found in follicular fluid concentrations of tumour necrosis factor alpha between the three groups. These results demonstrate that different concentrations of oxidative stress markers, oxidant enzymes and cytokines in low responders compared with high responders and oocyte donors may negatively impact ovarian response.

Can DNA fragmentation of neat or swim-up spermatozoa be used to predict pregnancy following ICSI of fertile oocyte donors?

This study compared the potential of assessing sperm DNA fragmentation (SDF) from neat semen and the subsequent swim-up (SU) procedure to predict pregnancy when conducting ICSI of fertile donor oocytes. Infertile females (n=81) were transferred embryos resulting from intracytoplasmic sperm injection (ICSI) of their partner's spermatozoa and proven donor oocytes. This model normalized the impact of female factor in putative sperm DNA repair. Semen was blindly assessed for SDF using Halosperm immediately following ejaculation (NS) and after swim-up at the time of ICSI fertilisation. There was a decrease in SDF values of the ejaculated semen sample following the swim-up protocol (P=0.000). Interestingly, pregnancy could be equally predicted from SDF values derived from either neat or swim-up semen samples. Receiver operator curves and the derived Youden's indices determined SDF cutoff values for NS and SU of 24.8% and 17.5%, respectively. Prediction of pregnancy from NS SDF had a sensitivity of 75% and a specificity of 69%, whereas for SU SDF was 78% and 73%, respectively. While increased levels of SDF negatively impact reproductive outcome, we have shown that a reduction in SDF following sperm selection using ICSI with proven donor oocytes is not mandatory for achieving pregnancy. This suggests that a certain level of DNA damage that is not detectable using current technologies could be impacting on the relative success of assisted reproductive technology (ART) procedures. Consequently, we propose a modification of the so called 'iceberg model' as a possible rationale for understanding the role of SDF in reproductive outcome.

DNA fragmentation dynamics in fresh versus frozen thawed plus gradient-isolated human spermatozoa.

The aim of this study was to compare the rate of sperm DNA fragmentation (rSDF; increase of SDF over time) in fresh and gradient isolated frozen-thawed semen samples from male sperm donors of proven fertility. SDF was assessed in the two samples obtained from the same fifteen male donors after 0.5, 1.5, 4.5, 6, 24, 48, and 72 h of incubation in a humidified atmosphere of 5% CO(2) in air at 37 degrees C. Analysis was performed based on chromatin dispersion patterns evaluated using the Halosperm kit. No significant differences in SDF were obtained when fresh and gradient-isolated frozen-thawed spermatozoa were compared at baseline. However, the rSDF shown by the two samples differed and gradient-isolation selected for sperm subpopulations showing a lower variance for SDF. At the individual level, sperm selection by density gradient purification in frozen-thawed samples did not improve the levels of SDF when compared with the values obtained in fresh samples at baseline.