Human embryos donated for human embryonic stem cell derivation

Human embryonic stem cells (hESCs), produced from human embryos, are demonstrating: utility and promise in disease modeling; enhanced and unique understanding of early events in basic genetic or molecular or cellular or epigenetic development; novel human approaches to pharmaceutical screening; pathways toward the discoveries of disease treatments and cures; and foundational importance for regenerative medicine. The regulatory landscape is rigorous, and rightly so. Here, we discuss the current US federal and state regulatory environment. A unique approach of presenting anonymized embryo donor statements is provided to personalize the decision-making process of human embryo donation for hESC derivation. From the uses of preimplantation genetic-tested and affected human embryos to derived disease-specific hESCs, one can glean the much needed information on early human genetics and developmental biology, which are presented here. Finally, we discuss the future uses of hESCs, and other pluripotent stem cells, in general and reproductive medicine.

Cleavage-stage human embryo arrest, is it embryo genetic composition or others?

Embryo transfer is a crucial step in IVF cycle, with increasing trend during the last decade of transferring a single embryo, preferably at the blastocyst stage. Despite increasing evidence supporting Day 5 blastocyst-stage transfer, the optimal day of embryo transfer remains controversial. The crucial questions are therefore, whether the mechanisms responsible to embryos arrest are embryo aneuploidy or others, and whether those embryos arrested in-vitro between the cleavage to the blastocyst stage would survive in-vivo if transferred on the cleavage-stage. We therefore aim to explore whether aneuploidy can directly contribute to embryo development to the blastocyst stage. Thirty Day-5 embryos, that their Day-3 blastomere biopsy revealed a single-gene defect, were donated by 10 couples undergoing preimplantation genetic testing treatment at our center. Affected high quality Day-3 embryos were cultured to Day-5, and were classified to those that developed to the blastocyst-stage and those that were arrested. Each embryo underwent whole genome amplification. Eighteen (60%) embryos were arrested, did not develop to the blastocyst stage and 12 (40%) have developed to the blastocyst stage. Nineteen embryos (63.3%) were found to be euploid. Of them, 12 (66.6%) were arrested embryos and 7 (58.3%) were those that developed to the blastocyst-stage. These figures were not statistically different (p = 0.644). Our observation demonstrated that the mechanism responsible to embryos arrest in vitro is not embryo aneuploidy, but rather other, such as culture conditions. If further studies will confirm that Day-5 blastocyst transfer might cause losses of embryos that would have been survived in vivo, cleavage-stage embryo transfer would be the preferred timing. This might reduce the cycle cancellations due to failure of embryo to develop to the blastocyst stage and will provide the best cumulative live birth-rate per started cycle.

GDF9 concentration in embryo culture medium is linked to human embryo quality and viability

PURPOSE

We aimed to evaluate the link between the GDF9 concentration in day 3 human embryo culture medium and embryo quality and viability.

METHODS

Two independent, prospective, observational studies were conducted. In study 1, a total of 280 embryos from 70 patients who obtained at least 4 embryos with 6-10 blastomeres (2 transferable and 2 non-transferable embryos) at day 3 were enrolled. In study 2, a total of 119 embryos from 61 patients (29 fully implanted and 32 non-implanted patients) were enrolled. The corresponding GDF9 concentrations in spent culture medium of embryos were quantified by ELISA assay. The expression pattern of GDF9 in human embryos was investigated using Q-PCR and immunofluorescence.

RESULTS

GDF9 mRNA and protein were detected from human oocytes to eight-cell embryos and displayed a slow decreasing trend. In study 1, GDF9 concentration in culture medium is lower for transferable embryos compared with non-transferable embryos (331 pg/mL (quartiles: 442, 664 pg/mL) vs. 518 pg/mL (quartiles: 328, 1086 pg/mL), P < 0.001), and increased commensurate with the diminution of the embryo quality (P < 0.001). In study 2, significantly lower GDF9 concentration was detected for implanted embryos than non-implanted embryos (331 pg/mL (quartiles: 156, 665 pg/mL) vs. 518 pg/mL (quartiles: 328, 1086 pg/mL), P < 0.001). The same trend was found between the embryos that led to live birth and those that failed.

CONCLUSION

The GDF9 concentration in culture medium is linked to embryo quality and viability, and exhibited the potential to be a non-invasive biomarker for embryo selection.

Cumulus cells of euploid versus whole chromosome 21 aneuploid embryos reveal differentially expressed genes

RESEARCH QUESTION

Can cumulus cells be used as a non-invasive target for the study of determinants of preimplantation embryo quality?

DESIGN

Cumulus cells were collected from monosomy 21, trisomy 21 and euploid embryos and subjected to RNA sequencing analysis and real-time polymerase chain reaction assays. The differential gene expression was analysed for different comparisons.

RESULTS

A total of 3122 genes in monosomy 21 cumulus cells and 19 genes in trisomy 21 cumulus cells were differentially expressed compared with euploid cumulus cells. Thirteen of these genes were differentially expressed in both monosomy and trisomy 21, compared with euploid, including disheveled segment polarity protein 2 (DVL2), cellular communication network factor 1 (CCN1/CYR61) and serum response factor (SRF), which have been previously implicated in embryo developmental competence. In addition, ingenuity pathway analysis revealed cell-cell contact function to be affected in both monosomy and trisomy 21 cumulus cells.

CONCLUSIONS

These findings support the use of cumulus cell gene expression analysis for the development of biomarkers evaluating oocyte quality for patients undergoing fertility preservation of oocytes.

Evaluation of deep convolutional neural networks in classifying human embryo images based on their morphological quality

A critical factor that influences the success of an in-vitro fertilization (IVF) treatment cycle is the quality of the transferred embryo. Embryo morphology assessments, conventionally performed through manual microscopic analysis suffer from disparities in practice, selection criteria, and subjectivity due to the experience of the embryologist. Convolutional neural networks (CNNs) are powerful, promising algorithms with significant potential for accurate classifications across many object categories. Network architectures and hyper-parameters affect the efficiency of CNNs for any given task. Here, we evaluate multi-layered CNNs developed from scratch and popular deep-learning architectures such as Inception v3, ResNET-50, Inception-ResNET-v2, NASNetLarge, ResNeXt-101, ResNeXt-50, and Xception in differentiating between embryos based on their morphological quality at 113 h post insemination (hpi). Xception performed the best in differentiating between the embryos based on their morphological quality.

Human pluripotent stem cells - Unique tools to decipher the effects of environmental and intracellular plastic pollution on human health

Increase in plastic pollution causes irreparable harm to the environment lasting for decades. While current data of plastic pollution include marine and terrestrial ecology, the impacts of degraded or intentionally produced microscopic-sized plastics on human health remain unknown. Here, we are proposing the usage of pluripotent stem cells, modern transcriptomics, and bioinformatics as a unique scientific tool to define the link between environmental and intracellular pollution, its outcome on early human development and origin of diseases. This commentary is an urgent appeal to the scientific and policy communities to invest more time and resources to establish reliable standards and methods to define and address the consequences of plastic pollution on human health.

Repeated cryopreservation process impairs embryo implantation potential but does not affect neonatal outcomes

RESEARCH QUESTION

Does repeated cryopreservation process affect embryo implantation potential and neonatal outcomes of human embryos?

DESIGN

This retrospective cohort study was conducted in the Reproductive Medicine Centre, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology. All assisted reproductive technology (ART) cycles were carried out between January 2014 and December 2018. Preferentially matched participants were divided into three groups according to the times of embryo cryopreservation: the fresh group (n = 249), the cryopreservation group (n = 244) and the re-cryopreservation group (n = 216). Embryo implantation rate, live birth rate, miscarriage rate and neonatal complication rate were compared among these three groups.

RESULTS

The embryo implantation rate, clinical pregnancy rate and live birth rate in the re-cryopreservation group were significantly lower, and the miscarriage rate also slightly increased. Logistic regression analysis indicated that embryos with repeated cryopreservation and lower trophectoderm scores were at higher risk of embryo implantation failure in single embryo transfer cycles (OR 1.79 and 1.56, respectively). No significant differences were observed in gender, gestational age, birthweight, neonatal abnormality and neonatal complications among the groups.

CONCLUSIONS

Our findings demonstrate the adverse effect of repeated cryopreservation on embryo implantation potential. The study offers embryologists and reproductive clinicians a warning of detrimental role of repeated cryopreservation. If unnecessary, it is strongly recommended to avoid repeated practice of vitrification and warming on embryos.

Potential ethical problems with human cerebral organoids: Consciousness and moral status of future brains in a dish

Human cerebral organoids (HCOs) are an in vitro model of early neural development, aimed at modelling and understanding brain development and neurological disorders. In just a few years there has been rapid and considerable progress in the attempt to create a brain model capable of showcasing the characteristics of the human brain. There are still strong limitations to address, including the absence of vascularization which makes it difficult to feed the central layers of the organoid. Nevertheless, some important features of the nervous system have recently been observed in cerebral organoids: they manifest electrical activity (i.e. communication between neurons), are sensitive to light stimulation and are able to connect to a spinal cord by sending impulses that make a muscle contract. Recent data show that cortical organoid network development at ten months resembles some preterm babies EEG patterns. Although cerebral organoids are not close to human brains so far due to their extremely simplified structure, this state of things gives rise to ethical concerns about the creation and destructive experimental use of human cerebral organoids. Particularly, one can wonder whether a human cerebral organoid could develop some degree of consciousness and whether, under certain conditions, it could acquire its own moral status with the related rights. In this article, I discuss the conditions under which HCOs could be granted their own moral status. For this purpose, I consider the hypothesis that HCOs might develop a primitive form of consciousness and investigate the ways in which it could be detected. In light of all this, I finally point out some cautionary measures that could be introduced into research on and with human cerebral organoids.

Human germline editing in the era of CRISPR-Cas: risk and uncertainty, inter-generational responsibility, therapeutic legitimacy

BACKGROUND

Clustered Regularly Interspaced Short Palindromic Repeats-associated (CRISPR-Cas) technology may allow for efficient and highly targeted gene editing in single-cell embryos. This possibility brings human germline editing into the focus of ethical and legal debates again.

MAIN BODY

Against this background, we explore essential ethical and legal questions of interventions into the human germline by means of CRISPR-Cas: How should issues of risk and uncertainty be handled? What responsibilities arise regarding future generations? Under which conditions can germline editing measures be therapeutically legitimized? For this purpose, we refer to a scenario anticipating potential further development in CRISPR-Cas technology implying improved accuracy and exclusion of germline transmission to future generations. We show that, if certain concepts regarding germline editing are clarified, under such conditions a categorical prohibition of one-generation germline editing of single-cell embryos appears not to be ethically or legally justifiable.

CONCLUSION

These findings are important prerequisites for the international debate on the ethical and legal justification of germline interventions in the human embryo as well as for the harmonization of international legal standards.

Dampened X-chromosomes in human pluripotent stem cells: dampening or erasure of X-upregulation?

The recent report of X-chromosome dampening in human preimplantation embryos remains controversial. Subsequently, Sahakyan et al. found evidence of X-chromosome dampening in human naïve pluripotent stem cells (hPSCs) as well. Here, we discuss whether X-dampening reported in hPSCs truly reflects the dampening of X-chromosomes or it is a consequence of the erasure of X-chromosome upregulation.

Systems based analysis of human embryos and gene networks involved in cell lineage allocation

BACKGROUND

Little is understood of the molecular mechanisms involved in the earliest cell fate decision in human development, leading to the establishment of the trophectoderm (TE) and inner cell mass (ICM) stem cell population. Notably, there is a lack of understanding of how transcriptional networks arise during reorganisation of the embryonic genome post-fertilisation.

RESULTS

We identified a hierarchical structure of preimplantation gene network modules around the time of embryonic genome activation (EGA). Using network models along with eukaryotic initiation factor (EIF) and epigenetic-associated gene expression we defined two sets of blastomeres that exhibited diverging tendencies towards ICM or TE. Analysis of the developmental networks demonstrated stage specific EIF expression and revealed that histone modifications may be an important epigenetic regulatory mechanism in preimplantation human embryos. Comparison to published RNAseq data confirmed that during EGA the individual 8-cell blastomeres are transcriptionally primed for the first lineage decision in development towards ICM or TE.

CONCLUSIONS

Using multiple systems biology approaches to compare developmental stages in the early human embryo with single cell transcript data from blastomeres, we have shown that blastomeres considered to be totipotent are not transcriptionally equivalent. Furthermore we have linked the developmental interactome to individual blastomeres and to later cell lineage. This has clinical implications for understanding the impact of fertility treatments and developmental programming of long term health.

Persistent right umbilical vein: a study using serial sections of human embryos and fetuses

Persistent right umbilical vein (PRUV) is a common anomaly of the venous system. Although candidates for future PRUV were expected to occur more frequently in earlier specimens, evaluation of serial horizontal sections from 58 embryos and fetuses of gestational age 5–7 weeks found that only two of these embryos and fetuses were candidates for anomalies. In a specimen, a degenerating right umbilical vein (UV) joined the thick left UV in a narrow peritoneal space between the liver and abdominal cavity, and in the other specimen, a degenerating left UV joined a thick right UV in the abdominal wall near the liver. In these two specimens, the UV drained into the normal, umbilical portion of the left liver. These results strongly suggested that, other than the usual PRUV draining into the right liver, another type of PRUV was likely to consist of the right UV draining into the left liver.

Chapter 9 Slow Freezing and Thawing of Human Cleavage Stage Embryos

The ability to store human embryos in a viable state at very low temperatures has been critical to the evolution of responsible practice in clinical Assisted Reproductive Technology (ART). It has encouraged a reduction in the frequency of simultaneous multiple embryo transfer and thereby reduced the risks associated with multiple pregnancy while maintaining high cumulative pregnancy rates from single oocyte collection cycles. In this chapter, we describe a simple slow freezing procedure for human early cleavage stage embryos that results in a high proportion of post-thaw embryos surviving and retaining their implantation potential.

The cumulative dose of gonadotropins used for controlled ovarian stimulation does not influence the odds of embryonic aneuploidy in patients with normal ovarian response

OBJECTIVE

Controlled ovarian hyperstimulation (COH) promotes multifollicular growth, increasing the chance of obtaining euploid embryos that will successfully implant. Whether aneuploidy is increased from COH with exogenous gonadotropins interfering with natural selection of dominant follicles is a concern. This study evaluates the association between gonadotropin exposure and aneuploidy.

METHODS

This is a retrospective cohort study of 828 patients that underwent 1122 IVF cycles involving controlled ovarian stimulation and trophectoderm biopsy for preimplantation genetic screening (PGS), from 2010 to 2015. Polymerase chain reaction (PCR) was used to assess aneuploidy. Kruskal-Wallis tests and logistic regression with generalized estimating equations (GEEs) were used for data analysis.

RESULTS

Overall, after controlling for patient age, ovarian reserve, stimulation protocol, days of stimulation, and diagnoses, there was no significant association between cumulative gonadotropin (GND) dose and the odds of aneuploidy (adjusted OR = 1.049, p = 0.232). Similarly, in cycles where patients did not require COH beyond cycle day 12, there was no significant association between cumulative gonadotropin dose and the odds of aneuploidy (adjusted OR = 0.909, p = 0.148). However, in cases where patients were stimulated past cycle day 12, there was a significant increase in the odds of aneuploidy (adjusted OR = 1.20, 95% CI 1.125-1.282, p < 0.0001) with increasing cumulative gonadotropin dose, with a small effect size (Cohen's d = 0.10, 95% CI 0.08-0.12). In this cohort, there was a 16.4% increase in the odds of aneuploidy for each 1000-u increase in cumulative GND exposure (adjusted OR = 1.164, p = 0.002). When the analysis was restricted to low responders (peak estradiol <500 pg/mL or <4 mature follicles achieved; there was no significant association between gonadotropin dose and aneuploidy (adjusted OR = 1.12, 95% CI 0.982-1.28, p = 0.09), regardless of the duration of COH required to reach vaginal oocyte retrieval.

CONCLUSION

The degree of exposure to exogenous gonadotropins did not significantly modify the likelihood of aneuploidy in patients with a normal ovarian response to stimulation (not requiring COH beyond cycle day 12). Patients requiring prolonged COH were demonstrated to have elevated odds of aneuploidy with increasing cumulative gonadotropin dose. This finding may reflect an increased tendency towards oocyte and embryonic aneuploidy in patients with a diminished response to gonadotropin stimulation.

Perineal raphe with special reference to its extension to the anus: a histological study using human fetuses

The raphe of the human penis and scrotum is considered to develop secondarily after disappearance of the initial midline seam by fusion of the bilateral genital folds. However, the fetal development was still obscure. We examined histological sections of 30 fetuses (17 males and 13 females) at 10–15 weeks. In male fetuses, the scrotum was not yet clearly identified because of no descent of testis. The perineal raphe was thin and wavy at 10 weeks, and it was continuous with and took a direction same as the inferior wall of the closed penile urethra after physiological hypospadias. Depending on growth of the bulbospongiosus muscle and corpus spongiosus penis, the midline intermuscular septum obtained a connection to the subcutaneous wavy raphe and made the latter thick and straight at 12–15 weeks. Notably, the perineal raphe extended posteriorly to attach to the external anal sphincter. In female fetuses, an epithelial fusion occurred along a short distance at the posterior end of the vestibule. However, in front of the external anal sphincter, a large midline mesenchymal tissue from the urorectal septum did not contain a raphe-like structure. Moreover, since the bilateral bulbospongiosus muscles were separated widely by the vestibule, they did not provide a midline septum. Fetal development of the perineal raphe was accelerated by reinforcement from the muscular septum. In contrast, without such a muscular support, the female raphe could not maintain its growth even if the seed appeared at the posterior end of the vestibule.

Activation of endogenous human stem cell-associated retroviruses (SCARs) and therapy-resistant phenotypes of malignant tumors

Recent reports revealed consistent activation of specific endogenous retroviral elements in human preimplantation embryos and embryonic stem cells. Activity of stem cell associated retroviruses (SCARs) has been implicated in seeding thousands of human-specific regulatory sequences in the hESC genome. Activation of specific SCARs has been demonstrated in patients diagnosed with multiple types of cancer, autoimmune diseases, and neurodegenerative disorders, and appears associated with clinically lethal therapy resistant death-from-cancer phenotypes in a sub-set of cancer patients diagnosed with different types of malignant tumors. A hallmark feature of human-specific SCAR integration sites is deletions of ancestral DNA. Analysis of human-specific genetic loci of SCARs' stemness networks in tumor samples of TCGA cohorts representing 29 cancer types suggests that this approach may facilitate identification of pan-cancer genomic signatures of clinically-lethal disease defined by the presence of somatic non-silent mutations, gene-level copy number changes, and transcripts and proteins' expression of SCAR-regulated host genes. Present analyses indicate that multiple lines of strong circumstantial evidence support the hypothesis that activation of SCARs' networks may play an important role in cancer progression and metastasis, perhaps contributing to the emergence of clinically-lethal therapy-resistant death-from-cancer phenotypes.

Morphological characteristics of human embryonic hepatic stem cells

AIM: To observe the morphological features, temporal-spatial distribution and differentiation of hepatic stem cells in the early stage of human embryonic livers.

METHODS: Paraffin sections were prepared from human embryos of 3 to 12 wk by routine method. Immunohistochemical staining was used to observe the development of human embryonic livers and hepatic stem cells as well as the expression of α-fetoprotein (AFP), c-Met and cytokeratin 19 (CK19) under light microscope.

RESULTS: Liver buds came into being in wk 3, hepatic cords formed in wk 4, and primal hepatic sinusoids were found in wk 5. The hepatic cells of the 3-5 wk displayed the typical features of immature cells: small size, a round or ovoid nuclei with dark color, scant cytoplasm with slight blue and a high ratio of nuclei to cytoplasm. Moreover, they were positive for AFP and c-Met. At 6 wk, a part of hepatocytes, whose numbers increased as the growth of the embryos, became larger with nuclei of slight color, which were negative for AFP and c-Met. At 10-12 wk, the AFP- and c-Met-positive cells were mainly found at the periportal region. The CK19-positive reaction began to appear in some hepatocytes which were similar to the AFP- and c-Met-positive cells at 7 wk. At 10-11 wk, the reaction was confined at the hepatocytes adjacent to the portal region, ductal plate and biliary epithelial cells. At 12 wk, the positive reaction was only found at the ductal plate and biliary epithelial cells. Furthermore, all the cells were positive for AFP, c-Met and CK19 at this time.

CONCLUSION: Hepatocytes of 3-5 wk, phenotyped AFP⁺/c-Met⁺, are homogenous and belong to the hepatic stem cells. At 6 wk, the hepatic stem cells begin to differentiate to hepatocyte system, and then to cholangiocyte system in the next week. Like oval cells in the adult liver, the hepatic stem cells mainly locate at the periportal region at 10-12 wk. The cells characterized by AFP⁺/c-Met⁺/CK19⁺ belong to the progenitor cells of biliary epithelial cells.