Permanence of de novo segmental aneuploidy in sequential embryo biopsies.

STUDY QUESTION: Is de novo segmental aneuploidy (SA) a biological event or an artifact that is erroneously interpreted as partial chromosome imbalance? SUMMARY ANSWER: The detection of de novo SA in sequential biopsies of preimplantation embryos supports the biological nature of SA. WHAT IS KNOWN ALREADY: Although some SAs are detected in oocytes and in blastocysts, the highest incidence is observed in cleavage-stage embryos. Based on these findings, we can postulate that the majority of cells affected by SAs are eliminated by apoptosis or that affected embryos mainly undergo developmental arrest. STUDY DESIGN, SIZE, DURATION: This retrospective study includes 342 preimplantation genetic testing for aneuploidy (PGT-A) cycles performed between January 2014 and December 2018. Chromosome analysis was performed on 331 oocytes, 886 cleavage-stage embryos and 570 blastocysts (n = 1787). From 268 expanded blastocysts, the blastocoelic fluid (BF) was also analyzed (resulting in 2025 samples in total). In cases of SAs involving loss or gain in excess of 15 Mb, embryos were not considered for transfer and sequential biopsies were performed at following stages. This resulted in 66 sets where the initial diagnosis of SAs (4 made in polar bodies, 25 in blastomeres and 37 in trophectoderm (TE) cells) was followed up. PARTICIPANTS/MATERIALS, SETTING, METHODS: A total of 2082 samples (2025 + 27 whole embryos) were processed by whole genome amplification followed by array comparative genomic hybridization. MAIN RESULTS AND THE ROLE OF CHANCE: The incidence of SAs was 6.3% in oocytes, increased to 16.6% in cleavage-stage embryos (P < 0.001) and decreased to 11.2% in blastocysts (P < 0.025 versus oocytes; P < 0.01 versus cleavage-stage embryos). The highest incidence of SAs was found in BFs (26.1%, P < 0.001). The analysis of 66 sets of sequential biopsies revealed that the initial finding was confirmed in all following samples from 39 sets (59.1% full concordance). In 12 additional sets, SAs were detected in some samples while in others the interested chromosome had full aneuploidy (18.2%). In three more sets, there was a partial concordance with the initial diagnosis in some samples, but in all TE samples the interested chromosome was clearly euploid (4.5%). In the remaining 12 sets, the initial SA was not confirmed at any stage and the corresponding chromosomes were euploid (18.2% no concordance). The pattern of concordance was not affected by the number of SAs in the original biopsy (single, double or complex) or by the absence or presence of concomitant aneuploidies for full chromosomes. LIMITATIONS, REASONS FOR CAUTION: Chromosome analyses were performed on biopsies that might not be representative of the true constitution of the embryo itself due to the occurrence of mosaicism. WIDER IMPLICATIONS OF THE FINDINGS: The permanence of SAs throughout the following stages of embryo development in more than half of the analyzed sets suggests for this dataset a very early origin of this type of chromosome imbalance, either at meiosis or at the first mitotic divisions. Since SAs remained in full concordance with the initial diagnosis until the blastocyst stage, a corrective mechanism seems not to be in place. In the remaining cases, it is likely that, as for full chromosome aneuploidy, mosaicism derived from mitotic errors could have occurred. In following cell divisions, euploid cell lines could prevail preserving the embryo chances of implantation. Due to the scarcity of data available, the transfer of embryos with SAs should be strictly followed up to establish possible clinical consequences related to this condition. STUDY FUNDING/COMPETING INTEREST(S): No specific funding was obtained. There are no conflicts of interest.

In vitro effect of gold and silver nanoparticles on human spermatozoa.

The cytotoxicity of Au/Ag nanoparticles (NPs) on human spermatozoa was investigated in vitro. Semen from donors were incubated (37 °C, 60'-120') with 30, 60, 125, 250 and 500 µM Au/Ag-NPs. Sperm motility was evaluated following WHO guidelines; sperm viability was assessed with eosin Y test. Au-NPs were characterised and localised with field emission gun-based scanning transmission electron microscope/energy dispersive spectroscopy and transmission electron microscopy. Both tested NPs exerted a significant dose-dependent effect on motility and viability of human spermatozoa (P < 0.001). Ag-NPs seem to show a slightly elevated toxicity although not significant (P > 0.05). Au-NPs were localised in spermatozoa, whereas Ag-NPs were undetectable. In conclusion, Au-NPs and Ag-NPs do not appear to be harmful for human spermatozoa up to high concentrations (250-500 µM) that are probably difficult to reach in vivo. It is mandatory to explore the genotoxic effect of NPs in germ cells.

Effect of quercetin, rutin, naringenin and epicatechin on lipid peroxidation induced in human sperm.

Quercetin, rutin, naringenin, epicatechin are flavonoids with diverse properties, including antioxidant potential. We evaluated, in vitro, the cytotoxicity of these flavonoids (20, 30, 50, 100, 200, 400 µM) in swim-up selected human sperm. Antioxidant activity was tested against tert-butylhydroperoxide induced lipid peroxidation using a C11-BODIPY(581/591) probe and transmission electron microscopy. A significant concentration-dependent effect on sperm viability (P<0.001) and motility (P<0.001) was observed. Lipid peroxidation was decreased in samples treated with 30 µM quercetin (P<0.01) and 30 µM rutin (P<0.05) versus samples incubated with tert-butylhydroperoxide alone. Naringenin (50-100 µM) showed a low protective effect and epicatechin (200 µM) was not efficacious. Transmission electron microscopy analysis confirmed the protective action of rutin and in particular quercetin on damages induced by lipid peroxidation. These results underlined the antioxidant properties of quercetin and rutin. A possible role of these compounds in the supplementation of media used during semen handling warrants attention and further studies.