Human Embryos Research Articles

ST6GALNAC1-mediated sialylation in uterine endometrial epithelium facilitates the epithelium-embryo attachment

IntroductionEmbryo implantation requires synergistic interaction between the embryo and the receptive endometrium. Glycoproteins and glycan-binding proteins are involved in endometrium-embryo attachment. Sialyl Tn (sTn), a truncated O-glycan, is catalyzed by ST6 N-Acetylgalactosaminide Alpha-2,6-Sialyltransferase 1 (ST6GALNAC1) and can be detected by specific Sialic-acid-binding immunoglobulin-like lectins (Siglecs). Whether the sTn-Siglecs axis supports embryo implantation remains unknown. ObjectivesThis paper aims to study the role of ST6GALNAC1/sTn-Siglecs axis in embryo implantation. MethodsST6GALNAC1 and sTn in human endometrium were analyzed by immunohistochemistry. An in vitro implantation model was conducted to evaluate the effects of ST6GALNAC1/sTn on the receptivity of human endometrial AN3CA cells to JAR spheroids. Immunoprecipitation combined with mass spectrometry analysis was carried out to identify the key proteins modified by sTn in endometrial cells. Siglec-6 in human embryos was analyzed by published single-cell RNA sequencing (scRNA-seq) datasets. Protein interaction assay was applied to verify the bond between the Siglec-6 with sTn-modified CD44. St6galnac1 siRNAs and anti-sTn antibodies were injected into the uterine horn of the mouse at the pre-implantation stage to evaluate the role of endometrial St6galnac1/sTn in embryo implantation. Siglec-G in murine embryos was analyzed by immunofluorescence staining. The function of Siglec-G is evidenced by uterine horn injection and protein interaction assay. ResultsBoth human and murine endometrium at the receptive stage exhibit higher ST6GALNAC1 and sTn levels compared to the non-receptive stage. Overexpression of ST6GALNAC1 significantly enhanced the receptivity of AN3CA cells to JAR spheroids. Inhibition of endometrial ST6GALNAC1/sTn substantially impaired embryo implantation in vivo. CD44 was identified as a carrier for sTn in the endometrial cells of both species. Siglec-6 and Siglec-G, expressed in the embryonic trophectoderm, were found to promote embryo attachment, which may be achieved through binding with sTn-modified CD44. ConclusionST6GALNAC1-regulated sTn in the endometrium aids in embryo attachment through interaction with trophoblastic Siglecs.

Morphological quality on Day 3 affects the pregnancy outcomes of low-quality euploid blastocysts: a retrospective cohort study.

Does the morphological quality on Day 3 influence the pregnancy outcomes of euploid blastocysts? The morphological quality on Day 3 affects the clinical pregnancy rate (CPR) and live birth rate (LBR) of low-quality euploid blastocysts. The morphological grading of Day 3 embryos affects the pregnancy outcome of cleavage-stage embryos and is an excellent indicator to predict embryo development potential. However, it is still unclear whether morphological quality on Day 3 is associated with pregnancy outcomes of the euploid blastocyst. This retrospective cohort study comprised 1275 patients who received single euploid blastocyst transfer between January 2016 and August 2021 at a tertiary teaching hospital. Patients were grouped into two groups according to the morphological grading on Day 3 of transferred blastocysts: high-quality (HQ, including Grades I and II) Day 3 embryos and low-quality (LQ, Grade III) Day 3 embryos. The primary outcomes were CPR and LBR. Interactions of development days (Day 5 and Day 6) and morphological quality (high- and low-quality) of blastocysts with morphological quality of Day 3 embryos on pregnancy outcomes were tested in the stratified analysis and logistic regression models. The multivariate logistic regression analysis was conducted to investigate the independent effect of the morphological quality of Day 3 embryos on pregnancy outcomes after adjusting for potentially confounding factors. The CPR and LBR of the HQ Day 3 embryos group were statistically higher than those of the LQ Day 3 embryos group (CPR: 59.73% versus 49.70%, respectively, P = 0.015; LBR: 49.73% versus 41.21%, respectively, P = 0.041). The development days of blastocysts did not exhibit a multiplicative interaction with the morphological quality of Day 3 embryos on the CPR (P for interaction = 0.648) and LBR (P for interaction = 0.925). The morphological quality of blastocysts exhibits a multiplicative interaction with the morphological quality of Day 3 embryos on the CPR (P for interaction = 0.020) and LBR (P for interaction = 0.012). After adjusting for potential confounders, the HQ Day 3 embryo group was positively associated with the CPR (adjusted odds ratio (aOR): 2.10, 95% CI: 1.31-3.36, P = 0.002) and LBR (aOR: 1.97, 95% CI: 1.20-3.25, P = 0.008) of LQ blastocysts. However, the morphological quality on Day 3 was not significantly associated with the CPR (aOR: 0.95, 95% CI: 0.58-1.55, P = 0.835) and LBR (aOR: 0.86, 95% CI: 0.53-1.40, P = 0.550) of HQ blastocysts. Selection and confounding bias introduced by the retrospective design cannot be completely eliminated in this study, although multivariable logistic analysis was conducted to adjust for potential confounders. Also, some subgroups had small sample sizes, which may reduce statistical power. Moreover, participants in our study only received single euploid blastocyst transfer, and whether the results could apply to blastocysts with unknown ploidy status is unclear. This study found that the morphological quality on Day 3 was significantly associated with the CPR and LBR of LQ blastocysts; Therefore, when only LQ euploid blastocysts are available for transfer, blastocysts derived from HQ Day 3 embryos are recommended. No external funding was obtained. The authors have no conflicts of interest to declare. N/A.

Setting the stage for embryo segmentation

Morphogen gradients are critical regulators of embryonic development. In this issue, Liu etal.1 introduce a microfluidic system that externally applies morphogen gradients to an invitro model of human embryo segmentation.It enables the investigation of signaling gradients during this developmental processat unprecedented levels of precision.

Effect of sequential cleavage and blastocyst embryo transfer compared to single cleavage stage embryo transfer on assisted reproductive technology outcome: An RCT.

Assisted reproductive technology (ART), offers hope for many infertile couples by increasing the chance of successful pregnancy. The success of in vitro fertilization depends on various factors, in which embryo transfer (ET) is one of the critical steps influencing in vitro fertilization success rates. Extended embryo culture and blastocyst-stage ET have been considered in ART due to their potential benefits including improved implantation rates. This study aimed to compare the outcomes of sequential ET vs single cleavage-stage ET in women undergoing a fresh ET cycle with a limited number of embryos. This randomized clinical trial was conducted on 140 women undergoing infertility treatments and candidates for fresh ET at the Research and Clinical Center for Infertility, Yazd, Iran from August 2023 to January 2024. Women with a number of embryos from 2-5 ( 2 and 5 available embryos) were randomly divided into 2 groups: One group underwent sequential ET (one cleavage-stage ET followed by one blastocyst ET) and the other group underwent single-step 2 cleavage-stage ET. The primary outcome was clinical pregnancy, and the secondary outcome included chemical pregnancy and early abortion rates. Our findings showed significantly higher rates of clinical (33.5% vs 13.6%, p = 0.003) and chemical (41.3% vs 18.2%, p = 0.004) pregnancies in the sequential ET group compared to the single-step cleavage ET group. The early abortion rate was higher in single-step cleavage ET (13% vs 44.4%, p = 0.053). Sequential fresh ET is a useful choice in women who have a limited number of embryos and can improve ART outcomes.

Distinct dynamics of parental 5-hydroxymethylcytosine during human preimplantation development regulate early lineage gene expression

The conversion of DNA 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC) by TET enzymes represents a significant epigenetic modification, yet its role in early human embryos remains largely unknown. Here we showed that the early human embryo inherited a significant amount of 5hmCs from an oocyte, which unexpectedly underwent de novo hydroxymethylation during its growth. Furthermore, the generation of 5hmC in the paternal genome after fertilization roughly followed the maternal pattern, which was linked to DNA methylation dynamics and regions of sustained methylation. The 5hmCs persisted until the eight-cell stage and exhibited high enrichment at OTX2 binding sites, whereas knockdown of OTX2 in human embryos compromised the expression of early lineage genes. Specifically, the depletion of 5hmC affected the activation of embryonic genes, which was further evaluated by ectopically expressing mouse Tet3 in human early embryos. These findings revealed distinct dynamics of 5hmC and unravelled its multifaceted functions in early human embryonic development.

The Embryological Interpretation of Gen 2:7 and its Use in Dyophysite Christology

Abstract This article traces the rise of the embryological interpretation of Gen 2:7 and how it came to provide arguments for dyophysite Christology. By the late 4th century, many Christian writers saw in the formation of Adam a depiction of the formation and ensoulment of a human embryo. Moreover, authors around the 5th century connected the embryological reading of Adam’s formation with the life of Christ in the womb. But in the 6th and 7th centuries, this interpretation of Gen 2:7 became controversial. Debates about Christ raised the stakes of disagreement over the time of human ensoulment, and embryological readings of Adam’s creation were caught up in these debates. In this context, East Syrian Babai the Great (551–628) deployed the embryological reading of Gen 2:7 against Christological rivals in defense of his theory of Christ’s delayed ensoulment in the womb. In doing so, he offers a biological account of Christ’s pre-ensouled life as a plant and zoophyte. But the connection between an embryological reading of Gen 2:7 and dyophysite Christology also prompted opponents to turn to exegetical strategies that excluded any analogy with delayed ensoulment. This article thus presents an example of how theological controversy and the history of science affected biblical exegesis.

Zygotic spindle orientation defines cleavage pattern and nuclear status of human embryos

The first embryonic division represents a starting point for the development of a new individual. In many species, tight control over the first embryonic division ensures its accuracy. However, the first division in humans is often erroneous and can impair embryo development. To delineate the spatiotemporal organization of the first mitotic division typical for normal human embryo development, we systematically analyzed a unique timelapse dataset of 300 IVF embryos that developed into healthy newborns. The zygotic division pattern of these best-quality embryos was compared to their siblings that failed to implant or arrested during cleavage stage. We show that division at the right angle to the juxtaposed pronuclei is preferential and supports faithful zygotic division. Alternative configurations of the first mitosis are associated with reduced clustering of nucleoli and multinucleation at the 2-cell stage, which are more common in women of advanced age. Collectively, these data imply that orientation of the first division predisposes human embryos to genetic (in)stability and may contribute to aneuploidy and age-related infertility.

The impact of antioxidant supplements on oocytes and preimplantation embryos of humans and mammals, and their potential application for mitigating the consequences of oxidative stress in vitro: a review

Nowadays, assisted reproductive technologies are becoming increasingly in demand in people's lives and activities. One of the most important stages of assisted reproductive technology is the cultivation of oocytes and embryos in vitro. The oxidative stress that arises during such cultivation is a great challenge associated with assisted reproductive technology-related activities. It manifests as an excessive amount of reactive oxygen species, resulting in damage to biomolecules, membranes, and other cell components, which significantly reduces the quality and quantity of oocytes and embryos. One possible solution may be the use of antioxidant supplements of various origins. In this review, we summarize and systematize data related to oxidative stress and the use of antioxidants during the cultivation of human, murine, and farm animal-derived oocytes and embryos. In conclusion, we highlight the need for further research to develop a personalized approach in the field of medical and veterinary-assisted reproductive technologies. One result of this approach may be an increase in the probability of obtaining a healthy fetus with the minimum number of in vitro fertilization attempts.

Intracytoplasmic sperm injection versus conventional in vitro insemination in couples with non-male infertility factor in the ‘real-world’ setting: analysis of the HFEA registry

BackgroundIn assisted reproductive technology (ART), the choice between intracytoplasmic sperm injection (ICSI) and conventional in vitro insemination (IVF) remains a pivotal decision for couples with female or unexplained infertility. The hypothesis that ICSI may not confer significant improvements in live birth rates in the absence of a male infertility factor was explored in this study.MethodsThis was a retrospective collection of data recorded by the Human Fertilisation and Embryology Authority (HFEA) in the UK from 2005 to 2018 and analysed through regression analysis models on both the entire dataset and a matched-pair subset. First fresh ART cycles were analysed according to the insemination technique in order to compare live birth as the main outcome. Cycles were included if complete information regarding infertility cause, female age, number of oocytes retrieved, allocation to ICSI or IVF, and treatment outcome in terms of live birth was available. Matching was performed at a 1:1 ratio between IVF and ICSI cycles according to the cause of infertility, female age, number of oocytes, and year of treatment.ResultsThis study, based on 275,825 first cycles, revealed that, compared with IVF, ICSI was associated with higher fertilization rates and lower cycle cancellations rates. However, ICSI was associated with a lower chance of implantation and live birth than IVF in cycles with female-only infertility: in the entire dataset, the adjusted odds of having a live birth decreased by a factor of 0.95 (95% CI 0.91–0.99, p = 0.011), while in the matched-pair analyses it decreased by a factor of 0.91 (95% CI 0.86–0.96, p = 0.003) using ICSI compared to IVF. For unexplained infertility cycles, the adjusted odds ratios for live birth in ICSI compared to IVF cycles were 0.98 (95% CI 0.95–1.01) in the entire dataset and 0.97 (95% CI 0.93–1.01) in the matched-pair analysis.ConclusionsCompared with IVF, ICSI was associated with a reduction in live births when ART was indicated due to female-only factors. Additionally, no significant improvements were associated with the use of ICSI in cycles with unexplained infertility. Our findings impose a critical reevaluation regarding the use of ICSI over IVF for cases with female-only factors and unexplained infertility.

Donor conception, direct-to-consumer genetic testing, choices, and procedural justice: an argument for reform of the Human Fertilisation and Embryology Act 1990.

In this article, using theories of procedural justice and 'slow violence', we consider potential reform of the Human Fertilisation and Embryology Act 1990. Our theoretical discussion is underpinned by findings from the ConnecteDNA project, exploring how people affected by donor conception experience direct-to-consumer genetic testing (DTCGT). The negative impacts of DTCGT, especially shock discoveries about the circumstances of someone's conception in adulthood, are linked to donor anonymity, and how its continued protection is experienced as a barrier to the rights and agency of donor-conceived people. We focus on two key issues relating to the donor information access process set out in section 31ZA of the 1990 Act. The first is that it excludes certain cohorts of donor-conceived people, creating inequalities of access to donor information. The second is the impact of the use of DTCGT to search for that information. We discuss what a procedurally just process of law reform would look like, concluding that, whatever (prospective) approach to donor anonymity is taken, the donor information access process should be the same for all donor-conceived people. We thus argue that, even were the status quo to be maintained, reform of the donor information access process with retrospective effect would be required.

Sex-specific DNA-replication in the early mammalian embryo

The timing of DNA replication in mammals is crucial for minimizing errors and influenced by genome usage and chromatin states. Replication timing in the newly formed mammalian embryo remains poorly understood. Here, we have investigated replication timing in mouse zygotes and 2-cell embryos, revealing that zygotes lack a conventional replication timing program, which then emerges in 2-cell embryos. This program differs from embryonic stem cells and generally correlates with transcription and genome compartmentalization of both parental genomes. However, consistent and systematic differences existed between the replication timing of the two parental genomes, including considerably later replication of maternal pericentromeric regions compared to paternal counterparts. Moreover, maternal chromatin modified by Polycomb Repressive Complexes in the oocyte, undergoes early replication, despite belonging to the typically late-replicating B-compartment of the genome. This atypical and asynchronous replication of the two parental genomes may advance our understanding of replication stress in early human embryos and trigger strategies to reduce errors and aneuploidies.

Using progesterone to follicular index ratio is better correlated with intracytoplasmic sperm injection outcome than using serum progesterone level alone.

to investigate the possibility of using the ratio of serum progesterone level to the number of follicles, according to ovarian response in the day of human chorionic gonadotrophin trigger, as a predictor of cycle outcome. A prospective intervensional study was conducted at Kamal Al-Samarai Hospital for Infertility Treatment and IVF during the period from December 2020 to September 2021. Ninety infertile women underwent intracytoplasmic sperm injection (ICSI) cycles using antagonist protocol. Moreover, once the patient reached triggering criteria, meticulous recording of follicular index together with serum estrogen level and serum progesterone level are measured. Fresh embryo transfer of cleavage stage embryo is done once serum progesterone level was less than 1.5 ng/mL. A follow-up to confirm pregnancy rate and cycle outcome was done. The study showed a positive pregnancy rate of 28.9%. The relationship between progesterone follicular index (Prog/FI) ratio and (ICSI) outcome was highly significant with a p value of 0.001. Additionally, an inverse relationship, as the ratio was lower the pregnancy rate was improved, was documented. The receiver operating characteristic (ROC) curve for progesterone follicular index ratio was 0.711 with a cut off value of 0.0354 ng/mL in addition to a sensitivity of 65.6 and a specificity of 65.4. The serum progesterone level is an independent factor for the prediction of intracytoplasmic sperm injection (ICSI) outcome, whereas the progesterone follicular index ratio can be used as a potential marker for predicting ICSI outcome in fresh embryo transfer.

In vitro culture of cynomolgus monkey embryos from blastocyst to early organogenesis.

Human early embryonic development is the cornerstone of a healthy baby. Abnormal early embryonic development may lead to developmental and pregnancy-related disorders. Accordingly, understanding the developmental events and mechanisms of human early embryonic development is very important. However, attempts to reveal these events and mechanisms are greatly hindered by the extreme inaccessibility of in vivo early human embryos. Fortunately, the emergence of in vitro culture (IVC) systems for mammalian embryos provides an alternative strategy. In recent years, different two-dimensional and three-dimensional IVC systems have been developed for human embryos. Ethical limitations restrict the IVC of human embryos beyond 14 days, which makes non-human primate embryos an ideal model for studying primate developmental events. Different culture systems have supported the development of monkey embryos to days postfertilization 14 and 25, respectively. The successful recapitulation of in vivo developmental events by these IVC embryos has greatly enriched our understanding of human early embryonic development, which undoubtedly helps us to develop possible strategies to predict or treat various gestation-related diseases and birth defects. In this protocol, we establish different two-dimensional and three-dimensional IVC systems for primate embryos, provide step-by-step culture procedures and notes, and summarize the advantages and limitations of different culture systems. Replicating this protocol requires a moderate level of experience in mammalian embryo IVC, and the embryo culture requires strict adherence to the procedures we have described.

Temporally resolved early bone morphogenetic protein-driven transcriptional cascade during human amnion specification.

Amniogenesis, a process critical for continuation of healthy pregnancy, is triggered in a collection of pluripotent epiblast cells as the human embryo implants. Previous studies have established that bone morphogenetic protein (BMP) signaling is a major driver of this lineage specifying process, but the downstream BMP-dependent transcriptional networks that lead to successful amniogenesis remain to be identified. This is, in part, due to the current lack of a robust and reproducible model system that enables mechanistic investigations exclusively into amniogenesis. Here, we developed an improved model of early amnion specification, using a human pluripotent stem cell-based platform in which the activation of BMP signaling is controlled and synchronous. Uniform amniogenesis is seen within 48 hr after BMP activation, and the resulting cells share transcriptomic characteristics with amnion cells of a gastrulating human embryo. Using detailed time-course transcriptomic analyses, we established a previously uncharacterized BMP-dependent amniotic transcriptional cascade, and identified markers that represent five distinct stages of amnion fate specification; the expression of selected markers was validated in early post-implantation macaque embryos. Moreover, a cohort of factors that could potentially control specific stages of amniogenesis was identified, including the transcription factor TFAP2A. Functionally, we determined that, once amniogenesis is triggered by the BMP pathway, TFAP2A controls the progression of amniogenesis. This work presents a temporally resolved transcriptomic resource for several previously uncharacterized amniogenesis states and demonstrates a critical intermediate role for TFAP2A during amnion fate specification.

Digital Twin for Continuous Production of Virus-like Particles toward Autonomous Operation.

Lentiviral vector and virus-like particle (VLP) manufacturing have been published in fed-batch upstream and batch downstream modes before. Batch downstream and continuous upstream in perfusion mode were reported as well. This study exemplifies development and validation steps for a digital twin combining a physical-chemical-based mechanistic model for all unit operations with a process analytical technology strategy in order to show the efforts and benefits of autonomous operation approaches for manufacturing scale. As the general models are available from various other biologic manufacturing studies, the main step is model calibration for the human embryo kidney cell-based VLPs with experimental quantitative validation within the Quality-by-Design (QbD) approach, including risk assessment to define design and control space. For continuous operation in perfusion mode, the main challenge is the efficient separation of large particle manifolds for VLPs and cells, including cell debris, which is of similar size. Here, innovative tangential flow filtration operations are needed to avoid fast blocking with low mechanical stress pumps. A twofold increase of productivity was achieved using simulation case studies. This increase is similar to improvements previously described for other entities like plasmid DNAs, monoclonal antibodies (mAbs), and single-chain fragments of variability (scFv) fragments. The advantages of applying a digital twin for an advanced process control strategy have proven additional productivity gains of 20% at 99.9% reliability.

Advanced human embryo research beyond the 14-day limit: A bioethical perspective from the Muslim world

Advancements in invitro human embryo research prompt a reconsideration of the 14-day rule, highlighting the integration of global religious perspectives, particularly Islam. Through analyzing classical Muslim scholars' perspectives and modern interdisciplinary Islamic bioethical discussions, we advocate extending the 14-day limit to at least 40days, with specified conditions.

An expert opinion on rescuing atypically pronucleated human zygotes by molecular genetic fertilization checks in IVF.

IVF laboratories routinely adopt morphological pronuclear assessment at the zygote stage to identify abnormally fertilized embryos deemed unsuitable for clinical use. In essence, this is a pseudo-genetic test for ploidy motivated by the notion that biparental diploidy is required for normal human life and abnormal ploidy will lead to either failed implantation, miscarriage, or significant pregnancy complications, including molar pregnancy and chorionic carcinoma. Here, we review the literature associated with ploidy assessment of human embryos derived from zygotes displaying a pronuclear configuration other than the canonical two, and the related pregnancy outcome following transfer. We highlight that pronuclear assessment, although associated with aberrant ploidy outcomes, has a low specificity in the prediction of abnormal ploidy status in the developing embryo, while embryos deemed abnormally fertilized can yield healthy pregnancies. Therefore, this universal strategy of pronuclear assessment invariably leads to incorrect classification of over 50% of blastocysts derived from atypically pronucleated zygotes, and the systematic disposal of potentially viable embryos in IVF. To overcome this limitation of current practice, we discuss the new preimplantation genetic testing technologies that enable accurate identification of the ploidy status of preimplantation embryos and suggest a progress from morphology-based checks to molecular fertilization check as the new gold standard. This alternative molecular fertilization checking represents a possible non-incremental and controversy-free improvement to live birth rates in IVF as it adds to the pool of viable embryos available for transfer. This is especially important for the purposes of 'family building' or for poor-prognosis IVF patients where embryo numbers are often limited.

Effects of whole life-cycle exposure to carbaryl on reproduction of female marine medaka (Oryzias melastigma) and their offspring

Carbaryl is widely used as a highly effective insecticide which harms the marine environment. This study aimed to assess the reproductive toxicity of chronic carbaryl exposure on female marine medaka and their female offspring. After a 180-day exposure from embryonic period to adulthood, females exhibited reduced attraction to males, decreased ovulation, increased gonadosomatic index and a higher proportion of mature and atretic follicles. These reproductive toxic effects of carbaryl may stem from changes in hormone levels and transcription levels of key genes along the HPG axis. Furthermore, maternal carbaryl exposure had detrimental effects on the offspring. F1 females showed the reproductive disorders similar to those observed in F0 females. The significant changes in the transcription levels of DNA methyltransferase and demethylase genes in the F0 and F1 generations of ovaries indicate changes in their DNA methylation levels. The changes in DNA methylation levels in F1 female marine medaka may lead to changes in the expression of certain reproductive key genes, such as an increase in the transcription level of cyp19a, which may be the reason for F1 reproductive toxicity. These findings indicate that maternal exposure may induce severe generational toxicity through alterations in DNA methylation levels. This study assesses the negative impacts of whole life-cycle carbaryl exposure on the reproductive and developmental processes of female marine medaka and its female offspring, while offering data to support the evaluation of the ecological risk posed by carbaryl in marine ecosystems.

3D-bioprinted gelatin methacryloyl hydrogel culture system emulating the oviduct environment for enhanced preimplantation embryo development

Oviducts have specific biomechanical properties that support fertilization and preimplantation embryo development, both of which are essential for successful pregnancy. However, conventional plastic-based human embryo culture does not recapitulate the biomechanical environment of the oviduct. Therefore, oviduct mimic culture systems that accurately emulate biophysical conditions for reproductive cells are a significant unmet clinical need. In the present study, we designed a three-dimensional (3D)-bioprinted optimal soft hydrogel system that accurately mimics the oviduct environment and investigated signaling factors during embryo development. We developed an oviduct tube-mimic hydrogel culture dish using gelatin methacryloyl (GelMA) 3D-bioprinted hydrogel. Quantitative assessment of hydrogel mechanical properties depended on the stiffness of the GelMA 3D-bioprinted hydrogel. Embryo quality was evaluated based on cleavage speed and blastocyst ratio on the GelMA hydrogel. Whole-transcriptome next-generation sequencing (NGS) analysis of embryos was used to identify biomechanical signaling factors. Our findings revealed that 10 kPa GelMA hydrogel culture conditions performed better with respect to development speed, blastocyst ratio, and hatching ratio than the control condition. Whole transcriptome NGS revealed up-regulation of mRNA processing genes and protein transport genes by the 7 and 10 kPa hydrogels. Furthermore, the inner cell mass and the number of Oct4+ cells were significantly higher in blastocysts cultured on 10 kPa hydrogel dishes than in those cultured on conventional hard plastic dishes. These findings demonstrate that optimized oviduct-mimic hydrogel-based 3D GelMA culture dishes could improve in vitro embryo development. Hence, 3D GelMA culture dishes may be useful as human embryo culture systems for assisted reproductive techniques.

Langerhans cell histiocytosis in children born after assisted reproductive technology

Research QuestionAre children born after Assisted reproductive technologies (ART), at higher risk of developing Langerhans cell histiocytosis (LCH)? DesignRecords of children conceived after ART recorded by the Human Fertilisation & Embryology Authority were linked to National Registry of Childhood Tumours records to determine numbers of children developing LCH. Calculated person years at risk were used in conjunction with LCH incidence in the general population, to determine expected cases if the cohort had the same incidence as the general population with similar age and sex, over the same calendar years. The standardised incidence ratio (SIR) was derived as the ratio of observed to expected cases. Exact 95% confidence intervals were calculated. Results118,155 children born after ART contributed 796,633 person years follow-up; 6.74 years average follow-up. Eight cases of LCH were identified compared to 3.75 expected (SIR 2.135, 95% Confidence Interval 0.92 to 4.21, p = 0.074). Significantly more cases were associated with being born after intra-cytoplasmic sperm injection (SIR 4.02; 95% CI 1.31-9.39) and with male factor parental infertility (SIR 5.41; 95% CI 1.47-13.84). Most children had single system disease (n=6). ConclusionsThis study found a non-statistically significant excess of cases of LCH in children born after assisted reproduction. Significantly more cases were identified in children born after ICSI and after male factor parental infertility. Absolute excess risks were small. Given the rarity of LCH and small numbers of cases included in this large cohort, further studies into the risk of LCH in children born after ART are indicated.