PGDIS position statement on the transfer of mosaic embryos 2021.

Chromosome testing strategies, such as preimplantation genetic testing for aneuploidy (PGT-A), improve initial IVF outcomes by avoiding unwitting transfer of aneuploid embryos in morphology-based selection practices. Newer technologies have revealed that some embryos may appear to have intermediate whole chromosome (or parts of a chromosome termed segmental) copy number results suggesting trophectoderm mosaicism. An embryo with a trophectoderm mosaic-range result may be the only option for transfer for some patients. Recent data suggest that such mosaic embryos can be transferred without added risk of abnormal birth outcomes but may be associated with increased implantation failure and miscarriage rates, with higher values of mosaicism appearing to be less favourable for producing good outcomes. In this Position Statement, we provide guidance to laboratories, clinics, clinicians and counsellors to assist in discussions on the utility and transfer of mosaic embryos.

Pseudo contrastive labeling for predicting IVF embryo developmental potential.

In vitro fertilization is typically associated with high failure rates per transfer, leading to an acute need for the identification of embryos with high developmental potential. Current methods are tailored to specific times after fertilization, often require expert inspection, and have low predictive power. Automatic methods are challenged by ambiguous labels, clinical heterogeneity, and the inability to utilize multiple developmental points. In this work, we propose a novel method that trains a classifier conditioned on the time since fertilization. This classifier is then integrated over time and its output is used to assign soft labels to pairs of samples. The classifier obtained by training on these soft labels presents a significant improvement in accuracy, even as early as 30 h post-fertilization. By integrating the classification scores, the predictive power is further improved. Our results are superior to previously reported methods, including the commercial KIDScore-D3 system, and a group of eight senior professionals, in classifying multiple groups of favorable embryos into groups defined as less favorable based on implantation outcomes, expert decisions based on developmental trajectories, and/or genetic tests.

Mitochondrial DNA quantification as a tool for embryo viability assessment: retrospective analysis of data from single euploid blastocyst transfers.

STUDY QUESTION: Does the amount of mitochondrial DNA (mtDNA) in blastocyst biopsy specimens have the potential to serve as a biomarker of euploid embryo implantation ability, independent of morphology? SUMMARY ANSWER: The results of this study strongly suggest that elevated mtDNA levels, above a previously defined threshold, are strongly associated with blastocyst implantation failure and represent an independent biomarker of embryo viability. WHAT IS KNOWN ALREADY: Improved methods of embryo selection are highly desirable in order to increase the efficiency of IVF treatment. At present, even the transfer of chromosomally normal embryos of high morphological grade cannot guarantee that a pregnancy will follow. Recently, it has been proposed that the quantity of mtDNA in embryonic cells may be an indicator of developmental potential, with higher levels of mtDNA associated with reduced implantation. However, thus far reported data sets have been relatively small and in some cases have lacked appropriate validation. STUDY DESIGN, SIZE, DURATION: This large, blinded, retrospective study involved the analysis of relative mtDNA levels in 1505 euploid blastocysts obtained from 490 couples undergoing preimplantation genetic testing for aneuploidy. Implantation outcomes were compared to mtDNA levels in order to determine the capacity of the method to predict viability and to assess the validity of previously established thresholds. PARTICIPANTS/MATERIALS, SETTING, METHODS: DNA from blastocyst biopsy samples was amplified and then subjected to aneuploidy analysis using next generation sequencing or array comparative genomic hybridization. Only those embryos classified as chromosomally normal had their mtDNA levels assessed. This analysis was undertaken retrospectively using quantitative real-time PCR, without knowledge of the outcome of embryo transfer. Predictions of implantation failure, based upon mtDNA levels were subsequently compared to the observed clinical results. All cycles involved the transfer of a single embryo. MAIN RESULTS AND THE ROLE OF CHANCE: Of all blastocysts analyzed, 9.2% (139/1505) contained mtDNA levels above a previously established viability threshold and were therefore predicted to have reduced chances of implantation. To the date of analysis, 282 euploid blastocysts had been transferred with an overall implantation rate of 65.6% (185/282). Of the transferred embryos, 249 contained levels of mtDNA in the normal range, 185 of which produced a pregnancy, giving an implantation rate of 74.3% for euploid embryos with 'normal' quantities of mtDNA. However, 33 of the transferred embryos were determined to have elevated mtDNA quantities. None of these led to a pregnancy. Therefore, the negative predictive value of mtDNA assessment in this cohort was 100% (33/33). The difference between the implantation rates for embryos with normal and elevated mtDNA levels was highly significant (P < 0.0001). The mtDNA thresholds, used for classification of embryos, were unaffected by female age or the clinic in which the IVF was undertaken. The probability of an embryo having elevated levels of mtDNA was not influenced by variation in embryo morphology. LIMITATIONS, REASONS FOR CAUTION: This study provides strong evidence that mtDNA quantification can serve as a valuable tool to assist the evaluation of blastocyst viability. However, to determine the true extent of any clinical benefits, other types of investigations, such as non-selection studies and randomized controlled trials, will also be necessary. WIDER IMPLICATIONS OF THE FINDINGS: The results of this study suggest that mtDNA quantity can serve as an independent biomarker for the prediction of euploid blastocyst implantation potential. Prospective studies should now be undertaken to confirm these results. Additionally, investigations into the underlying biological cause(s) of elevated mtDNA levels and an enhanced understanding of how they relate to diminished implantation potential would be invaluable. STUDY FUNDING/COMPETING INTEREST(S): This study was supported by funding provided by Reprogenetics. None of the authors have any competing interests.

Ten-year experience with preimplantation genetic diagnosis (PGD) at the New York University School of Medicine Fertility Center.

We describe our experience of over 300 cycles of preimplantation genetic diagnosis (PGD) and report clinical pregnancy rates (35%-67%) that support using this technology to screen for genetic disorders and chromosomal abnormalities. In clinical practice for over ten years, PGD offers couples the earliest form of genetic screening and may help improve ongoing pregnancy rates in poor-prognosis patients.

Ooplasmic influence on nuclear function during the metaphase II-interphase transition in mouse oocytes.

Nuclear and pronuclear transfer procedures were used to assess the functional competence of the nucleus and cytoplasm of mouse germinal vesicle-stage oocytes denuded of granulosa cells and matured in vitro or in vivo before artificial activation using a sequential treatment of A23187 + cycloheximide. Following activation, in vitro-matured oocytes were "fertilized" by inserting a male pronucleus (PN), cultured to the 2-cell stage, and then transferred to the oviducts of foster mothers. No live births were noted, whereas a 17% live birth rate was observed when in vivo-matured oocytes were used. The developmental competency of other zygotes was similarly assessed following the exchange of haploid PN of matured and activated eggs with the female PN of fertilized zygotes. When PN of oocytes subjected to maturation and activation in vitro were transferred, only 1 of 79 reconstructed zygotes developed to term. In contrast, the live birth rate was 21% (11 of 53) for zygotes reconstructed with PN from in vivo-matured oocytes. Moreover, a live birth rate of 23% (8 of 35) was observed for reconstructed zygotes with female PN from "hybrid" oocytes created by transferring the metaphase II nuclei of in vitro-matured oocytes into enucleated, in vivo-matured oocytes before activation. Such results suggest that the nucleus of an in vitro-matured oocyte can support embryonic development, but only when it is activated in the proper ooplasmic milieu. The cellular factors creating this ooplasmic milieu appear to develop normally in vivo during follicle maturation to metaphase II, but they fail to do so when the oocytes are denuded of granulosa cells and cultured in vitro before the final stages of maturation. In parallel studies, male and female PN of in vivo-fertilized zygotes were inserted into oocytes that were activated and enucleated following either in vitro or in vivo maturation. Live birth rates were comparable at 19% (5 of 27) and 18% (9 of 49), respectively, suggesting that, regardless of the environment of the final stages of oocyte maturation, the resultant ooplasm is competent to support all aspects of embryonic development once activation and PN formation has been completed. Such findings only point further toward the importance of the condition of the ooplasmic milieu at the time of chemical activation. Whether a similar situation exists when eggs are activated following sperm penetration remains to be determined.

Fertility and maternal age strategies to improve pregnancy outcome.

In humans, the live birth rate drops precipitously with increasing maternal age, and this decline is associated with increases in the incidence of oocyte and embryo aneuploidy. Preimplantation aneuploidy screening has improved pregnancy outcome by significantly lowering the miscarriage rate. Nevertheless, aneuploidy screening only identifies the affected embryos; it does not attempt to correct the underlying biologic problem. Anomalies in chromosome segregation can result from a dysfunctional first or second meiotic division in the egg or develop after fertilization during the first few mitoses of early embryonic development. In both instances, ooplasmic anomalies may account for the nuclear problem. Low cell levels of cytoplasmic proteins (e.g., cytoskeletal elements, enzymes, energy stores, cell cycle regulatory proteins) may lead to a dysfunctional division of chromosomes during egg maturation or following fertilization. Ooplasmic injection is a micromanipulation technique that has produced pregnancies in patients with a history of poor-quality, fragmented embryos. Germinal vesicle transfer is a research procedure used to investigate the ooplasmic-nuclear interplay regulating cell cycle, maturation, and fertilization. Both these techniques may prove to be effective in improving the quality of eggs from patients of advanced maternal age.

Uterine transplantation, abdominal trachelectomy, and other reproductive options for cancer patients.

More and more women with cancer issues are now raising fertility concerns as survival improves and childbearing is delayed. Pregnancy is no longer contraindicated in cancer patients including breast and endometrial cancer survivors. In fact, survival in patients treated for breast cancer who subsequently become pregnant is actually higher than that in patients who do not become pregnant. "Therapeutic" abortions are no longer recommended. Assisted reproductive technology (ART) have been associated with ovarian neoplasms, but the association is probably not causal. Neither ART nor hormone replacement is contraindicated in cancer patients. Our institution is very supportive of patients and the difficult decisions cancer survivors face. Using a program of counseling and close collaboration between oncologists, perinatologists, and reproductive endocrinologists, informed patients are offered every possible option, including ART and uterine transplantation, to achieve their family planning objectives.

Factors useful in predicting the success of oocyte donation: a 3-year retrospective analysis.

OBJECTIVE: To establish prognostic relevance of parameters assessed in oocyte donation cycles. DESIGN: Retrospective analysis. SETTING: Large university-based donor oocyte program. PATIENT(S): All oocyte recipient cycles achieving embryo transfer from September 1995 to October 1998. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Pregnancy. RESULT(S): Recipient age and reproductive status, day 9 and 12 serum estradiol (E(2)) levels and a progesterone (P) level obtained 2 days after initiation of hormonal therapy did not correlate with pregnancy. Endometrial thickness, but not endometrial pattern, was useful in predicting pregnancy outcome. The clinical pregnancy and live-birth rate in cycles where the endometrial thickness was less than 8 mm was significantly lower when compared to cycles with an endometrial thickness > or =9 mm. Cycles where optimal quality embryos were transferred had the highest implantation (36%), clinical pregnancy (63%) and live birth (54%) rates and these rates were significantly higher than those of cycles where only poor quality embryos were available for transfer (10% implantation, 17% clinical pregnancy, and 8% live birth rates, respectively; P<.05). CONCLUSION(S): The most reliable predictive factors for pregnancy in oocyte donation cycles are the quality of the embryos transferred and the recipient's mid-cycle endometrial thickness. Recipient monitoring should minimally include ultrasound assessment of endometrial thickness.

A two- versus three-embryo transfer: the oocyte donation model.

OBJECTIVE: To compare implantation and pregnancy rates in oocyte recipients undergoing a two-embryo versus three-embryo transfer, 3 days after retrieval. DESIGN: Retrospective comparative analysis. SETTING: University-based in vitro fertilization center. PATIENT(S): All oocyte recipients undergoing embryo transfer from January 1, 1997 through August 31, 1999. INTERVENTION(S): Recipients received two or three embryos. MAIN OUTCOME MEASURE(S): Implantation, and clinical and multiple pregnancy rates. RESULT(S): Seventy-three recipients underwent a two-embryo transfer, and 376 had three embryos replaced. The numbers of oocytes retrieved (12.7 +/- 0.89 vs. 13.1 +/- 0.36) and embryos obtained (8.05 +/- 0.65 vs. 8.77 +/- 0.27) did not differ between the two-embryo and three-embryo transfer groups, nor did the proportion of patients with embryo cryopreservation (54.3% vs. 42.6%, respectively). There was no significant difference in pregnancy or implantation rates when comparing those patients with a two-embryo transfer to those with a three-embryo transfer. Significantly, 13.8% of the pregnancies in the three-embryo transfer group were triplet. CONCLUSION(S): Reducing the number of embryos transferred in an oocyte donation cycle can lower the incidence of triplet pregnancies without significantly lowering the overall pregnancy rate.

Analysis of Oct-4 expression and ploidy in individual human blastomeres.

Oct-4, a decisive factor that maintains totipotency in murine embryonic and germ cells, is exclusively expressed in such cells. In mice, different levels of oct-4 expression in blastomeres predict development towards inner cell mass (ICM) (high oct-4) or trophectoderm (TE) (low oct-4). To address whether the mouse model also applies to human embryos, the cytoplasm of individual human blastomeres from normally and abnormally fertilized embryos was tested for Oct-4 expression by reverse transcription-polymerase chain reaction (RT-PCR). The nuclei of the same blastomeres were subjected to fluorescence in-situ hybridization (FISH) to determine ploidy. A significant difference in Oct-4 mRNA levels was revealed between blastomeres. The distribution of blastomeres with high Oct-4 levels varied according to the cleavage stage of the embryo: the more blastomeres, the lower the percentage with high Oct-4 levels. Aneuploid blastomeres did not exhibit lower Oct-4 mRNA levels than diploid ones. Thus, differential Oct-4 expression in individual human blastomeres appears to direct cells towards the ICM or TE lineages without regard to chromosomal status. Oct-4 might be used as a marker in preimplantation genetic diagnosis to identify embryogenic blastomeres.

Efficacy and safety of ganirelix acetate versus leuprolide acetate in women undergoing controlled ovarian hyperstimulation.

OBJECTIVE: To assess the efficacy, safety, and local tolerance of ganirelix acetate for the inhibition of premature luteinizing hormone (LH) surges in women undergoing controlled ovarian hyperstimulation (COH). DESIGN: Phase III, multicenter, open-label randomized trial. SETTING: In vitro fertilization (IVF) centers in North America. PATIENT(S): Healthy female partners (n = 313) in subfertile couples for whom COH and IVF or intracytoplasmic sperm injection were indicated. INTERVENTION(S): Patients were randomized to receive one COH cycle with ganirelix or the reference treatment, a long protocol of leuprolide acetate in conjunction with follitropin-beta for injection. OUTCOME MEASURE(S): Number of oocytes retrieved, pregnancy rates, endocrine variables, and safety variables. RESULT(S): The mean number of oocytes retrieved per attempt was 11.6 in the ganirelix group and 14.1 in the leuprolide group. Fertilization rates were 62.4% and 61.9% in the ganirelix and leuprolide groups, respectively, and implantation rates were 21.1% and 26.1%. Clinical and ongoing pregnancy rates per attempt were 35.4% and 30.8% in the ganirelix group and 38.4% and 36.4% in the leuprolide acetate group. Fewer moderate and severe injection site reactions were reported with ganirelix (11.9% and 0.6%) than with leuprolide (24.4% and 1.1%). CONCLUSION(S): Ganirelix is effective, safe, and well tolerated. Compared with leuprolide acetate, ganirelix therapy has a shorter duration and fewer injections but produces a similar pregnancy rate.

Oct-4 expression in inner cell mass and trophectoderm of human blastocysts.

The expression of the transcription factor Oct-4 is thought to be one of the decisive factors that maintain totipotency in embryonic and germ cells. In mice, oct-4 is exclusively expressed in germ cells and totipotent cells of the embryo. In humans, Oct-4 is expressed in germ cells, embryonic stem cells and whole embryos at various stages of development. However, there is limited information about the distribution of Oct-4 expression in human embryos. In an attempt to address this issue, the inner cell mass (ICM) and trophectoderm (TE) of 17 human blastocysts were separated and Oct-4 mRNA expression individually assessed by reverse transcription-polymerase chain reaction (RT-PCR). In discarded blastocysts that developed from two pronuclear zygotes, the mean Oct-4 expression was 31 times higher in totipotent ICM cells than in differentiated TE cells. This finding suggests that, in accordance with data from the mouse, Oct-4 is highly expressed in human ICM cells as opposed to TE cells; this in turn supports the hypothesis that Oct-4 plays a similar role to maintain totipotency in these two species.

In-vitro development of mouse zygotes following reconstruction by sequential transfer of germinal vesicles and haploid pronuclei.

We evaluated whether mouse oocytes reconstructed by germinal vesicle (GV) transfer can develop to blastocyst stage. The oocytes were artificially activated with sequential treatment of A23187 and anisomycin; fertilization was then established by transfer or exchange of pronuclei with those of zygotes fertilized in vivo. Type 1 zygotes were constructed by placing the male haploid pronucleus from a zygote into the cytoplasm of an oocyte that underwent GV transfer, in-vitro maturation and activation; for type 2 zygotes, the female pronucleus was removed from a zygote and replaced with the female pronucleus of an oocyte subjected to GV transfer, in-vitro maturation and activation. Karyotypes of activated oocytes and type 2 zygotes were also subjected to analysis. When cultured in human tubal fluid (HTF) medium, reconstructed oocytes matured and, following artificial activation, consistently developed a pronucleus with a haploid karyotype; the activation rate for this medium was two- to three-fold higher than that of oocytes cultured in M199 (87% versus 30% respectively). Following transfer of a male pronucleus, only 47% of the type 1 zygotes developed to morula or blastocyst stage and embryo morphology was poor. In contrast, 73% of the type 2 zygotes developed to morula or blastocyst stage, many even hatching, with few morphological anomalies. Normal karyotypes were observed in 88% of the type 2 zygotes analysed. These observations demonstrate that the nucleus of a mouse oocyte subjected to sequential nuclear transfer at GV and pronucleus stages is, nonetheless, capable of maturing meiotically, activating normally and supporting embryonic development to hatching blastocyst stage. In contrast, the developmental potential of the cytoplasm of such oocytes appears to be compromised by these procedures.

Preimplantation genetic diagnosis in two families at risk for recurrence of Herlitz junctional epidermolysis bullosa.

The Herlitz type of junctional epidermolysis bullosa (H-JEB) is a severe inherited bullous disease which leads to the early demise of the affected newborn. Mutations in the genes encoding the 3 polypeptides of the anchoring filament protein laminin 5 underlie this condition. We studied 2 families with affected children who previously died from H-JEB. Mutation screening using heteroduplex analysis and direct sequencing of the PCR products revealed a previously described hotspot mutation in LAMB3 (R635X), and a novel delayed termination codon in LAMB3 in the first proband. In the second proband, we found a novel initiation codon mutation in LAMB3, and a novel 2 bp deletion in LAMB3. For preimplantation genetic diagnosis (PGD) in these families, we developed nested multiplex PCR assays, amplifying the mutations and informative intragenic polymorphisms in the probands. Single embryonic cells were biopsied from 8-cell embryos using standard techniques, and subjected to the multiplex PCR assay followed by restriction enzyme digestion. Embryos found not to carry either mutation were transferred to the mothers, and a pregnancy was established in the second family as evidenced by the elevated level of HCG, although the pregnancy did not persist. This study illustrates the feasibility of PGD for an inherited skin disorder for the first time.