Perinatal outcomes for transfer of blastocysts vitrified and warmed in defined solutions with recombinant human albumin: 374 babies born after 898 embryo transfers

Stepped vitrification technique for human ovarian tissue cryopreservation

The advantage of stepped vitrification (SV) is avoiding ice crystal nucleation, while decreasing the toxic effects of high cryoprotectant concentrations. We aimed to test this method for human ovarian tissue cryopreservation. Ovarian cortex was taken from 7 fertile adult women. Samples were subjected to an SV protocol performed in an automatic freezer, which allowed sample transfer to ever higher concentrations of dimethyl sulfoxide (DMSO) as the temperature was reduced. Histological evaluation of the vitrified-warmed tissue showed large numbers of degenerated follicles after 24 hours of in vitro culture. We therefore evaluated DMSO perfusion rates by X-ray computed tomography, ice crystal formation by freeze-substitution, and cell toxicity by transmission electron microscopy, seeking possible reasons why follicles degenerated. Although cryoprotectant perfusion was considered normal and no ice crystals were formed in the tissue, ultrastructural analysis detected typical signs of DMSO toxicity, such as mitochondria degeneration, alterations in chromatin condensation, cell vacuolization and extracellular matrix swelling in both stromal and follicular cells. The findings indicated that the method failed to preserve follicles due to the high concentrations of DMSO used. However, adaptations can be made to avoid toxicity to follicles caused by elevated levels of cryoprotectants.

Effects of different open cryo-carriers on embryo survival and clinical outcome in frozen embryo transfer cycle patients

The purpose of this study was to compare the efficacy of different open cryo-carriers: the CryoloopTM, CryotopTM, and CryoleafTM, in embryo survival and clinical outcome in patients with frozen embryo transfer (FET) cycle. We analyzed the embryo survival rate and clinical outcome in 325 patients of 348 FET cycles vitrified with the CryoloopTM (160 cycles), CryotopTM (105 cycles), or CryoleafTM (83 cycles). No significant differences were observed in embryo survival rate (98.8% vs. 100% vs. 97.7%, p > 0.05), HCG positive rate (58.8% vs. 63.8% vs. 57.8%, p > 0.05), biochemical pregnancy rate (6.9% vs. 11.4% vs. 9.6%, p > 0.05), or implantation rate (33.2% vs. 37.4% vs. 34.1%, p > 0.05) in the three groups respectively. The early abortion rate of the CryoloopTM group was significantly higher than that of the CryotopTM and CryoleafTM group (27.1% vs. 3.6% and 7.5%, p < 0.05). At the same time, the average female age of the CryoloopTM group was significantly older by 1 year than that of the CryotopTM and CryoleafTM group (33.29 ± 4.71 years vs. 31.96 ± 4.27 years and 31.1 ± 4.28 years, p < 0.05). There was no significant difference in take home baby rate (38.1% vs. 46.7% vs. 43.4, p > 0.05) or birth weight among the groups (2893.5 ± 780.8 g vs. 2778.4 ± 710.0 g vs. 2724.5 ± 838.8 g, p > 0.05). No case of neonatal malformation was observed in the present study. Overall, CryotopTM and CryoleafTM were effective for embryo vitrification at both the cleavage and blastocyst stage according to the results of clinical outcome and infant characteristics. However, CryoloopTM led to a decreased positive HCG rate and increased early abortion rate, heightened at the cleavage stage.

ABBREVIATIONS

LN₂: liquid nitrogen; CPA: cryoprotectant; ART: assisted reproductive technology; IVF: in vitro fertilization; ICSI: intracytoplasmic sperm injection; BMI: body mass index; FSH: follicular stimulation hormone; COH: controlled ovarian hyperstimulation; FET: frozen embryo transfer; mm: millimeter; HCG: human chorionic gonadotropin; RCT: randomized clinical trial; NC: natural cycle; AC: artificial cycle; EM: equilibration medium; DMSO: dimethyl sulphoxide; EG: ethylene glycol; VM: vitrification medium; WM: warming medium.

PARTIALLY CONSTRAINED SEX ALLOCATION AND THE INDIRECT EFFECTS OF ASSISTED REPRODUCTIVE TECHNOLOGIES ON THE HUMAN SEX RATIO

Infertility affects around 15% of human couples and in many countries approximately 1-4% of babies are born following Assisted Reproductive Technologies (ART). Several ART techniques are used and these differentially affect the sex ratio of offspring successfully produced. These direct effects on sex ratio also have the potential to influence, indirectly, the sex ratios of offspring born to untreated couples. This is of concern because human sex ratio bias may adversely affect public health. Here the extent of indirect effects of ART that could operate, via Fisherian frequency-dependent natural selection, on the progeny sex ratio of unassisted members of a population is heuristically modelled. Given the degrees to which ART techniques bias sex ratios directly, it is predicted that well over 20% of couples would have to reproduce via ART for there to be any discernible effect on the sex ratios produced, in response, by the remainder of the population. This value is greater than the estimated prevalence of infertility problems among human couples. It is concluded that providing ART to couples with fertility problems does not currently generate significant ethical issues or public health concern in terms of indirect effects on the offspring sex ratios of untreated couples.

Comparison of vitrified outcomes between human early blastocysts and expanded blastocysts

We compared the vitrified outcomes between early and expanded blastocysts with or without laser drilling. The grade III embryos from the patients undergoing in vitro fertilization-embryo transfer (IVF-ET) in our reproductive center from September 2009 to February 2015 were incubated into early blastocysts and expanded blastocysts. The early blastocysts and expanded blastocysts were, respectively, divided into laser group (vitrification after laser drilling), non-laser group (direct vitrification), and control group (fresh non-vitrified blastocysts). After thawing, the blastular anabiosis rate, expansion rate, hatching rate, and apoptosis were observed in each group and then were compared amongst groups. This study indicated that the blastular expansion rate (all P < 0.01) and hatching rate (all P < 0.01) were significantly lower, but the blastular apoptosis (all P < 0.05) was significantly higher in both laser and non-laser groups than in the control group in the early blastocysts. In the expanded blastocysts, the blastular anabiosis rate was significantly higher in the laser group than in the non-laser group (P < 0.01), and the blastular expansion rate was significantly higher, but the blastular apoptosis was significantly lower in both laser group and control group than in the non-laser group (all P < 0.05). The blastular expansion rate (all P < 0.01) and hatching rate (all P < 0.01) were significantly higher, but the blastular apoptosis (all P < 0.05) was significantly lower in the expanded laser group than in both early laser and early non-laser groups. We conclude that vitrification for laser-drilling expanded blastocysts can achieve the best outcomes.

Developmental capacity and implantation potential of the embryos with multinucleated blastomeres

The presence of multinucleated blastomeres (MNBs) in embryos is associated with poor developmental competence in assisted reproductive technologies. This phenomenon is observed not only in humans but also in other animal species. The purpose of the present study was to investigate the characteristics of embryos with MNBs (MNB embryos) that could be utilized in embryo transfer. The developmental rate of MNB embryos to the blastocyst stage (50.8%) was significantly lower than that of normal embryos (73.3%) (P < 0.05). The clinical pregnancy rates of fresh embryo transfer (ET) using day 2 or day 3 embryos were significantly lower in MNB embryos (5.1%) compared with normal embryos (24.0%) (P < 0.05). In the case of frozen-thawed ET using a single vitrified/warmed blastocyst, however, the clinical pregnancy rate of MNB embryos was close to that of normal embryos (59.1% vs. 52.8%). Thus, the findings of the present study suggest that the frozen-thawed ET of MNB embryos might improve the potential for implantation followed by successful pregnancy.