Genome-wide 5-hydroxymethylcytosine patterns in human spermatogenesis are associated with semen quality.

We performed immunofluorescent analysis of DNA hydroxymethylation and methylation in human testicular spermatogenic cells from azoospermic patients and ejaculated spermatozoa from sperm donors and patients from infertile couples. In contrast to methylation which was present throughout spermatogenesis, hydroxymethylation was either high or almost undetectable in both spermatogenic cells and ejaculated spermatozoa. On testicular cytogenetic preparations, 5-hydroxymethylcytosine was undetectable in mitotic and meiotic chromosomes, and was present exclusively in interphase spermatogonia Ad and in a minor spermatid population. The proportions of hydroxymethylated and non-hydroxymethylated diploid and haploid nuclei were similar among samples, suggesting that the observed alterations of 5-hydroxymethylcytosine patterns in differentiating spermatogenic cells are programmed. In ejaculates, a few spermatozoa had high 5-hydroxymethylcytosine level, while in the other ones hydroxymethylation was almost undetectable. The percentage of highly hydroxymethylated (5-hydroxymethylcytosine-positive) spermatozoa varied strongly among individuals. In patients from infertile couples, it was higher than in sperm donors (P<0.0001) and varied in a wider range: 0.12-21.24% versus 0.02-0.46%. The percentage of highly hydroxymethylated spermatozoa correlated strongly negatively with the indicators of good semen quality - normal morphology (r=-0.567, P<0.0001) and normal head morphology (r=-0.609, P<0.0001) - and strongly positively with the indicator of poor semen quality: sperm DNA fragmentation (r=0.46, P=0.001). Thus, the immunocytochemically detected increase of 5hmC in individual spermatozoa is associated with infertility in a couple and with deterioration of sperm parameters. We hypothesize that this increase is not programmed, but represents an induced abnormality and, therefore, it can be potentially used as a novel indicator of semen quality.

Outcomes of IVF cycles coupled with PGS by aCGH of embryos from donor and autologous oocytes, transferred after vitrification to women of advanced maternal age.

It is well documented that aneuploidy rate in preimplantation embryos increases with the mother's age, and at the same time the number of oocytes diminishes. Consequently, for patients of advanced maternal age two options are available to overcome these limitations: use of oocytes from young donors, or use of own oocytes coupled with preimplantation genetic screening (PGS) for 24 chromosomes. However, it is not clear which strategy might be more effective. The aim of this retrospective study was to evaluate outcomes of IVF cycles coupled with transfer of vitrified embryos from donor or autologous oocytes, both with or without PGS. Our results demonstrate that while after PGS clinical pregnancy, twin pregnancy and spontaneous abortion rates are similar for embryos from donor and autologous oocytes, these rates are dramatically worse in all cycles without PGS. Therefore, PGS can be recommended as a screening method to all patients of advanced maternal age even when donor oocytes are used.