DNA double strand breaks in human spermatozoa can be predictive for assisted reproductive outcome.

Sperm DNA status has been reported to predict fertility outcomes in infertile men. The terminal deoxynucleotidyl transferase-mediated dUDP nick-end labelling test (TUNEL) is the most widely used method to evaluate this; however, its prognostic value is still debated. One hundred infertile men undergoing intracytoplasmic sperm injection (ICSI) and 61 fertile men were tested for sperm parameters, sex hormones and sperm DNA status by chromatin tests (acridine orange, aniline blue, decondensation) and by direct assays (TUNEL and phosphorylated histone H2AX-γH2AX). In both groups, the prognostic value of each parameter to predict assisted clinical pregnancy was compared. Sperm parameters (P < 0.05 or P < 0.01), FSH levels (P < 0.05) and DNA status (P < 0.05 to P < 0.001) were significantly different in participants compared with controls. Among infertile men, 47 had positive and 53 had ICSI outcome. Both chromatin analysis and TUNEL test were unable to distinguish individuals who had successful outcomes from those who failed ICSI treatments. γH2AX percentage and γH2AX fragmentation index were significantly higher in sperm from non-pregnant compared with pregnant couples (P < 0.05 and P < 0.01). γH2AX assay is more predictive of ICSI outcome than TUNEL in infertile couples with male factor infertility.

Head birefringence properties are associated with acrosome reaction, sperm motility and morphology.

Birefringence in sperm heads reflects an organized and very compacted texture, indicating nuclear and acrosomal structural normality. This study performed a direct analysis of the acrosome integrity in single spermatozoa to verify whether a pattern of total or partial head birefringence reflected the acrosome status. The morphology in fresh samples was assessed according to World Health Organization criteria while the characteristics of birefringence were evaluated by polarized light. Acrosome integrity was evaluated by fluorescein isothiocyanate Pisum sativum agglutinin that binds selectively to the acrosome content. According to the results, a reacted acrosome was present in 96% of spermatozoa with partial birefringence and only in 35% of those with totally birefringent heads. A great proportion of sperm cells with normal morphology showed total birefringence both in the presence (59%) or in the absence of motility (45%; P < 0.01), while in morphologically abnormal spermatozoa the frequency of total birefringence was comparable to that of partial birefringence irrespective of motility (26% and 27%, respectively, in motile spermatozoa; 22% and 19%, respectively, in immotile spermatozoa). These data support a strong association between partial birefringence and reacted acrosome and show that the patterns of birefringence vary depending on sperm motility and morphology.

The role of preimplantation diagnosis for aneuploidies.

The clinical application of preimplantation genetic diagnosis (PGD) for aneuploidy has confirmed the hypothesis that implantation failure and spontaneous abortions are frequently due to aneuploidy. Following PGD, a higher implantation rate and a lower incidence of spontaneous abortions are obtained in patient categories where aneuploidy is the main cause of reproductive failure: women in advanced reproductive age, patients with an altered karyotype due to translocations or gonosomal mosaicism, and patients with recurrent spontaneous abortions. In these cases, the transfer of euploid embryos overcomes the poor prognosis condition in these couples. As expected, aneuploidy increases proportionally with female age; however, not all the chromosomes studied show this trend, suggesting that segregation errors could occur at different rates for each chromosome in relation to maternal age. Furthermore, the retrospective analysis of the results obtained in patients who repeated at least twice a PGD cycle permitted to estimate their chances of reproducing the same pattern of chromosomal abnormalities and consequently evaluating their possibility of a pregnancy: when no euploid embryos are detected at the first attempt, the chance of on-term pregnancy is below 10%; however, this chance is approximately 30% for couples with at least two euploid embryos in the first cycle.