Human in vitro fertilisation and developmental biology: a mutually influential history

Toward developing human organs via embryo models and chimeras

Developing functional organs from stem cells remains a challenging goal in regenerative medicine. Existing methodologies, such as tissue engineering, bioprinting, and organoids, only offer partial solutions. This perspective focuses on two promising approaches emerging for engineering human organs from stem cells: stem cell-based embryo models and interspecies organogenesis. Both approaches exploit the premise of guiding stem cells to mimic natural development. We begin by summarizing what is known about early human development as a blueprint for recapitulating organogenesis in both embryo models and interspecies chimeras. The latest advances in both fields are discussed before highlighting the technological and knowledge gaps to be addressed before the goal of developing human organs could be achieved using the two approaches. We conclude by discussing challenges facing embryo modeling and interspecies organogenesis and outlining future prospects for advancing both fields toward the generation of human tissues and organs for basic research and translational applications.

Bridging the Gap: Animal Models in Next-Generation Reproductive Technologies for Male Fertility Preservation

This review aims to explore advanced reproductive technologies for male fertility preservation, underscoring the essential role that animal models have played in shaping these techniques through historical contexts and into modern applications. Rising infertility concerns have become more prevalent in human populations recently. The surge in male fertility issues has prompted advanced reproductive technologies, with animal models playing a pivotal role in their evolution. Historically, animal models have aided our understanding in the field, from early reproductive basic research to developing techniques like artificial insemination, multiple ovulation, and in vitro fertilization. The contemporary landscape of male fertility preservation encompasses techniques such as sperm cryopreservation, testicular sperm extraction, and intracytoplasmic sperm injection, among others. The relevance of animal models will undoubtedly bridge the gap between traditional methods and revolutionary next-generation reproductive techniques, fortifying our collective efforts in enhancing male fertility preservation strategies. While we possess extensive knowledge about spermatogenesis and its regulation, largely thanks to insights from animal models that paved the way for human infertility treatments, a pressing need remains to further understand specific infertility issues unique to humans. The primary aim of this review is to provide a comprehensive analysis of how animal models have influenced the development and refinement of advanced reproductive technologies for male fertility preservation, and to assess their future potential in bridging the gap between current practices and cutting-edge fertility techniques, particularly in addressing unique human male factor infertility.

Prenatal Tests Undertaken by Muslim Women Who Underwent IVF Treatment, Secular Versus Religious: An Israeli Study

Our goal was to determine if differences exist in the attitudes of religious Muslim women living in Israel toward prenatal testing and pregnancy termination after undergoing in vitro fertilization (IVF) compared to the secular Muslim women who had undergone IVF. Six hundred and ninety-nine Muslim women from cities and villages participated, 47% city-dwellers; 53% village-dwellers; 50%-secular; 50%-religious. Secular women who had undergone IVF performed more invasive tests and terminated more pregnancies due to an abnormal fetus than religious women. More genetic counseling must be provided explaining the different prenatal tests and the problems in raising an abnormal child.

Heterogeneity of nucleolar morphology in four-cell mouse embryos after IVF: association with developmental potential

In mammals, around fertilization, the nucleolus of embryos transforms into the nucleolus precursor bodies (NPBs), which continue to mature until the blastocyst stage, leading to distinct morphological changes. In our study, we observed two types of nucleolar morphology in mouse in vitro fertilized embryos at the four-cell stage, which we refer to single nucleolus (SN) and multiple nucleoli (MN). To visualize nucleolar morphology, four-cell embryos were immunostained with anti-NOPP140 antibody. These embryos were categorized into five types based on the number of blastomeres carrying SN: SN4/MN0, SN3/MN1, SN2/MN2, SN1/MN3, and SN0/MN4, with percentages of 13, 27, 21, 23 and 9, respectively. Next, using a light microscope, we divided the four-cell in vitro fertilized embryos without fixation into two groups: those with at least two blastomeres displaying SN (SN embryos) and those without (MN embryos). Notably, significantly more SN embryos developed into blastocysts and offspring at 18.5 dpc compared with MN embryos. Furthermore, SN embryos displayed a higher NANOG-positive cell number at the blastocyst stage, significantly lower body and placental weights, resulting in a higher fetal/placental ratio. These findings suggest a close association between nucleolar state at the four-cell stage and subsequent developmental potential.

Conception by fertility treatment and cardiometabolic risk in middle childhood

OBJECTIVE

To evaluate whether children conceived using assisted reproductive technology (ART) or ovulation induction (OI) have greater cardiometabolic risk than children conceived without treatment.

DESIGN

Clinical assessments in 2018-2019 in the Upstate KIDS cohort.

SETTING

Clinical sites in New York.

PATIENT(S)

Three hundred thirty-three singletons and 226 twins from 448 families.

INTERVENTION(S)

Mothers reported their use of fertility treatment and its specific type at baseline and approximately 4 months after delivery. High validity of the self-reported use of ART was previously confirmed. The children were followed up from infancy through 8-10 years of age. A subgroup was invited to participate in clinic visits.

MAIN OUTCOME MEASURE(S)

The measurements of blood pressure (BP), arterial stiffness using pulse wave velocity, anthropometric measures, and body fat using bioelectrical impedance analysis were performed (n = 559). The levels of plasma lipids, C-reactive protein, and hemoglobin A1c were measured using blood samples obtained from 263 children.

RESULT(S)

The average age of the children was 9.4 years at the time of the clinic visits Approximately 39% were conceived using fertility treatment (18% using ART and 21% using OI). Singletons conceived using fertility treatment (any type or using ART or OI specifically) did not statistically differ in systolic or diastolic BP, heart rate, or pulse wave velocity. Singletons conceived using OI were smaller than singletons conceived without treatment, but the average body mass index of the latter was higher (z-score: 0.41 [SD, 1.24]) than the national norms. Twins conceived using either treatment had lower BP than twins conceived without treatment. However, twins conceived using OI had significantly higher arterial stiffness (0.59; 95% CI, 0.03-1.15 m/s), which was attenuated after accounting for maternal BP (0.29; 95% CI, -0.03 to 0.46 m/s). Twins did not significantly differ in size or fat measures across the groups. The mode of conception was not associated with the levels of lipids, C-reactive protein, or glycosylated hemoglobin.

CONCLUSION(S)

Clinical measures at the age of 9 years did not indicate greater cardiometabolic risk in children conceived using ART or OI compared with that in children conceived without treatment.

CLINICAL TRIAL REGISTRATION NUMBER

ClinicalTrials.gov #NCT03106493.

Regulation of posterior Hox genes by sex steroids explains vertebral variation in inbred mouse strains

A series of elegant embryo transfer experiments in the 1950s demonstrated that the uterine environment could alter vertebral patterning in inbred mouse strains. In the intervening decades, attention has tended to focus on the technical achievements involved and neglected the underlying biological question: how can genetically homogenous individuals have a heterogenous number of vertebrae? Here I revisit these experiments and, with the benefit of knowledge of the molecular-level processes of vertebral patterning gained over the intervening decades, suggest a novel hypothesis for homeotic transformation of the last lumbar vertebra to the adjacent sacral type through regulation of Hox genes by sex steroids. Hox genes are involved in both axial patterning and development of male and female reproductive systems and have been shown to be sensitive to sex steroids in vitro and in vivo. Regulation of these genes by sex steroids and resulting alterations to vertebral patterning may hint at a deep evolutionary link between the ribless lumbar region of mammals and the switch from egg-laying to embryo implantation. An appreciation of the impact of sex steroids on Hox genes may explain some puzzling aspects of human disease, and highlights the spine as a neglected target for in utero exposure to endocrine disruptors.

Case Report: Twin Pregnancy Gives Birth to a Girl with Partial Trisomy 21 Mosaicism after in vitro Fertilization and Embryo Transfer

Objective: To report a rare case in which an IVF-ET twin pregnancy gave birth to a partial trisomy 21 chimera girl.

Design: Case report.

Setting: University hospital.

Patient: A girl with partial trisomy 21 mosaicism after in vitro fertilization and embryo transfer.

Interventions:In vitro fertilization (IVF) and embryo transfer (ET).

Main Outcome Measure: Karyotype analysis, Copy Number Variation sequencing (CNV-seq), stLFR-WGS, and Short Tandem Repeat (STR) analysis.

Results: Being assisted with IVF and EF technology, the couple successfully gave birth to twin sisters at 37 weeks of gestational age. The NonInvasive Prenatal Testing (NIPT) and Nuchal Translucency (NT) examination showed no detectable genetic abnormalities during pregnancy. However, the younger infant displayed growth retardation and feeding difficulties after birth, which was not observed in her twin sister. Further genetic counseling and diagnosis suggested that she is a Chimera with complex partial trisomy 21. The stLFR-WGS assay showed multiple CNV variations in Chr21 and STR analysis confirmed the paternal origin of the additional fragments.

Conclusion: It is rare for IVF-ET-assisted twin pregnancy to give birth to a girl with a complex combination of abnormal Chr21, which might result from paternal chromosome rearrangement during meiosis and mitosis.

From lessons on the long-term effects of the preimplantation environment on later health to a "modified ART-DOHaD" animal model

Background

At its earliest stages, mammalian embryonic development is apparently simple but vulnerable. The environment during the preimplantation period, which only lasts a couple of days, has been implicated in adult health, extending to such early stages the concept of the developmental origin of health and disease (DOHaD).

Methods

In this review, we first provide a brief history of assisted reproductive technology (ART) focusing on in vitro culture and its outcomes during subsequent development mainly in mice and humans. Further, we introduce the "MEM mouse," a novel type 2 diabetes mouse model generated by in vitro culture of preimplantation embryos in alpha minimum essential medium (αMEM).

Main findings

The association between ART and its long-term effects has been carefully examined for its application in human infertility treatment. The "MEM mouse" develops steatohepatitis and kidney disease with diabetes into adulthood.

Conclusion

The close association between the environment of preimplantation and health in postnatal life is being clarified. The approach by which severe mouse phenotypes are successfully induced by manipulating the environment of preimplantation embryos could provide new chronic disease animal models, which we call "modified ART-DOHaD" animal models. This will also offer insights into the mechanisms underlying their long-term effects.

Live-Birth Prediction of Natural-Cycle In Vitro Fertilization Using 57,558 Linked Cycle Records: A Machine Learning Perspective

BACKGROUND

Natural-cycle in vitro fertilization (NC-IVF) is an in vitro fertilization (IVF) cycle without gonadotropins or any other stimulation of follicular growth. Previous studies on live-birth prediction of NC-IVF were very few; the sample size was very limited. This study aims to construct a machine learning model to predict live-birth occurrence of NC-IVF using 57,558 linked cycle records and help clinicians develop treatment strategies.

DESIGN AND METHODS

The dataset contained 57,558 anonymized register patient records undergoing NC-IVF cycles from 2005 to 2016 filtered from 7bsp;60,732 records in the Human Fertilisation and Embryology Authority (HFEA) data. We selected matching records and features through data filtering and feature selection methods. Two groups of twelve machine learning models were trained and tested. Eight metrics, e.g., F1 score, Matthews correlation coefficient (MCC), the area under the receiver operating characteristic curve (AUC), etc., were computed to evaluate the performance of each model.

RESULTS

Two groups of twelve models were trained and tested. The artificial neural network (ANN) model performed the best in the machine learning group (F1 score, 70.87%; MCC, 50.37%; and AUC score, 0.7939). The LogitBoost model obtained the best scores in the ensemble learning group (F1 score, 70.57%; MCC, 50.75%; and AUC score, 0.7907). After the comparison between the two models, the LogitBoost model was recognized as an optimal one.

CONCLUSION

In this study, NC-IVF-related datasets were extracted from the HFEA data, and a machine learning-based prediction model was successfully constructed through this largest NC-IVF dataset currently. This model is universal and stable, which can help clinicians predict the live-birth success rate of NC-IVF in advance before developing IVF treatment strategies and then choose the best benefit treatment strategy according to the patients' wishes. As "use less stimulation and back to natural condition" becomes more and more popular, this model is more meaningful in the decision-making assistance system for IVF.

Infertility Treatment Now and in the Future

Treatment of infertility has evolved as understanding of reproduction has improved. Fertility promoting surgery still is performed and recent advances have broken new ground. Hormonal treatments to correct gonadal dysfunction have been developed, but multiple gestation continues to be a significant complication. Assisted reproductive technologies have improved such that in vitro fertilization and its variants increasingly are used to treat nearly all causes of infertility. Advances in assisted reproduction are of 2 types: (1) incremental optimization of existing techniques and (2) development of new, disruptive technologies. Artificial intelligence and stem cell technologies are poised to have impact in the near future.