6 ANEUPLOIDY TOLERANCE IN RHESUS MACAQUE PRE-IMPLANTATION EMBRYOS VIA MICRONUCLEI FORMATION, CELLULAR FRAGMENTATION, AND BLASTOMERE EXCLUSION

2017 ◽  
Vol 29 (1) ◽  
pp. 110 ◽  
Author(s):  
B. L. Daughtry ◽  
J. L. Rosenkrantz ◽  
N. Lazar ◽  
N. Redmayne ◽  
K. A. Nevonen ◽  
...  
Keyword(s):  
Rhesus Macaque ◽  
Inner Cell Mass ◽  
Cell Mass ◽  
Time Lapse ◽  
Confocal Imaging ◽  
Chromosomal Mosaicism ◽  
Human Embryos ◽  
Cleavage Stage ◽  
Chromosomal Breakage

A primary contributor to in vitro fertilization (IVF) failure is the presence of unbalanced chromosomes in pre-implantation embryos. Previous array-based and next-generation sequencing (NGS) studies determined that ~50 to 80% of human embryos are aneuploid at the cleavage stage. During early mitotic divisions, many human embryos also sequester mis-segregated chromosomes into micronuclei and concurrently undergo cellular fragmentation. We hypothesised that cellular fragmentation represents a response to mis-segregated chromosomes that are encapsulated into micronuclei. Here, we utilised the rhesus macaque pre-implantation embryo as a model to study human embryonic aneuploidy using a combination of EevaTM time-lapse imaging for evaluating cell divisions, single-cell/-fragment DNA-Sequencing (DNA-Seq), and confocal microscopy of nuclear structures. Results from our time-lapse image analysis demonstrated that there are considerable differences in the timing of the first and third mitotic divisions between rhesus blastocysts and those that arrested before this stage in development (P < 0.01; ANOVA). By examining the chromosome content of each blastomere from cleavage stage embryos via DNA-Seq, we determined that rhesus embryos have an aneuploidy frequency up to ~62% (N = 26) with several embryos exhibiting chromosomal mosaicism between blastomeres (N = 6). Certain blastomeres also exhibited reciprocal whole chromosomal gains or losses, indicating that these embryos had undergone mitotic non-disjunction early in development. In addition, findings of reciprocal sub-chromosomal deletions/duplications among blastomeres suggest that chromosomal breakage had occurred in some embryos as well. Embryo immunostaining for the nuclear envelope protein, LAMIN-B1, demonstrated that fragmented cleavage-stage rhesus embryos often contain micronuclei and that cellular fragments can enclose DNA. Our DNA-Seq analysis confirmed that cellular fragments might encapsulate whole and/or partial chromosomes lost from blastomeres. When embryos were immunostained with gamma-H2AX, a marker of chromatin fragility, we observed distinct foci solely in micronuclei and DNA-containing cellular fragments. This suggests that micronuclei may be ejected from blastomeres through the process of cellular fragmentation and, once sequestered, these mis-segregated chromosomes become highly unstable and undergo DNA degradation. Finally, we also observed that ~10% of embryos prevented cellular fragments or large blastomeres from incorporating into the inner cell mass or trophectoderm at the blastocyst stage (n = 5). Upon confocal imaging, multiple nuclei and intense gamma-H2AX foci were found in a large unincorporated blastomere in one of the blastocysts. Altogether, our findings demonstrate that the rhesus embryo responds to segregation errors by eliminating chromosome-containing micronuclei via cellular fragmentation and/or selecting against aneuploid blastomeres that fail to divide during pre-implantation development with significant implications for human IVF.

41 Delineating the molecular connections between mitotic aneuploidy, micronucleation, and cellular fragmentation in pre-implantation bovine embryos

2019 ◽  
Vol 31 (1) ◽  
pp. 146
Author(s):  
K. E. Brooks ◽  
B. L. Daughtry ◽  
S. S. Fei ◽  
M. Y. Yan ◽  
B. Davis ◽  
...  
Keyword(s):  
Dna Sequencing ◽  
Rna Sequencing ◽  
Live Cell ◽  
Confocal Imaging ◽  
Chromosomal Mosaicism ◽  
Human Embryos ◽  
Bovine Embryos ◽  
Cleavage Stage ◽  
Cell Stage

Whole chromosomal abnormalities (aneuploidy) that arise during early embryo development are a major contributor to in vitro fertilization failure. It is estimated that ~50 to 80% of human embryos contain aneuploid cells, which contribute to high levels of chromosomal mosaicism detected by pre-implantation genetic screening. Previous studies estimate that 32 to 88% of bovine embryos are aneuploid at the 2-cell stage, advocating cattle as a physiologically relevant model to study the mechanisms mediating meiotic and/or mitotic errors. In cleavage-stage human embryos, a process called cellular fragmentation is associated with aneuploidy, and when used in conjunction with assessment of early mitotic timing, can largely distinguish chromosomally normal and abnormal embryos. We recently demonstrated that some cellular fragments contain chromosomal material that likely began as mis-segregated chromosomes that were encapsulated into micronuclei. Given that bovine embryos exhibit cellular fragmentation, albeit to a lesser extent than human embryos, we hypothesise that cellular fragmentation is a response to micronucleation and represents a conserved mechanism to eliminate mis-segregated chromosomes from the pre-implantation embryo. Using a combination of live-cell imaging, single-cell DNA-sequencing, whole-embryo RNA-sequencing, quantitative RT-PCR, and multicolour confocal microscopy, we aim to further investigate the correlation between these phenomena using in vitro-produced bovine embryos. Similar to humans, the first three mitotic divisions are able to successfully predict progression to the blastocyst stage (N=84). Bovine embryos frequently contained multi-/micro-nuclei, and DNA-sequencing of individual bovine blastomeres up to 12 cells confirmed that ~58 to 87% of cleavage-stage bovine embryos are aneuploidy (N=38) and often detectable by abnormal cell divisions. Transcriptional profiling of fragmented versus non-fragmented bovine embryos via RNA-sequencing identified a small subset of differentially abundant genes at the 4-cell stage. Pathway analysis showed reduced abundance of genes associated with the cytoskeleton, microtubules, and spindle in 4-cell embryos with cellular fragmentation as well as enrichment of membrane targeting and vesicle fusion pathways. The potential role of these cellular components in micronucleation and cellular fragmentation is being assessed by microinjecting bovine zygotes with fluorescently labelled mRNA mCherry-H2B (chromatin marker) and mCitrine-LaminB1 (nuclear envelope marker), followed by overnight live-cell multicolour confocal imaging (Zeiss LSM 880 with AiryScan; Zeiss, Thornwood, NY, USA). Results from these studies contribute to our knowledge of early embryogenesis with translational application to help ameliorate embryonic loss in women and cattle.

The human blastocyst: cell number, death and allocation during late preimplantation development in vitro

Development ◽  
1989 ◽  
Vol 107 (3) ◽  
pp. 597-604 ◽  
Author(s):  
K. Hardy ◽  
A.H. Handyside ◽  
R.M. Winston
Keyword(s):  
Cell Death ◽  
Inner Cell Mass ◽  
Cell Mass ◽  
Cell Number ◽  
Blastocyst Stage ◽  
Human Embryos ◽  
Cell Numbers ◽  
Human Blastocyst ◽  
Development In Vitro

The development of 181 surplus human embryos, including both normally and abnormally fertilized, was observed from day 2 to day 5, 6 or 7 in vitro. 63/149 (42%) normally fertilized embryos reached the blastocyst stage on day 5 or 6. Total, trophectoderm (TE) and inner cell mass (ICM) cell numbers were analyzed by differential labelling of the nuclei with polynucleotide-specific fluorochromes. The TE nuclei were labelled with one fluorochrome during immunosurgical lysis, before fixing the embryo and labelling both sets of nuclei with a second fluorochrome (Handyside and Hunter, 1984, 1986). Newly expanded normally fertilized blastocysts on day 5 had a total of 58.3 +/− 8.1 cells, which increased to 84.4 +/− 5.7 and 125.5 +/− 19 on days 6 and 7, respectively. The numbers of TE cells were similar on days 5 and 6 (37.9 +/− 6.0 and 40.3 +/− 5.0, respectively) and then doubled on day 7 (80.6 +/− 15.2). In contrast, ICM cell numbers doubled between days 5 and 6 (20.4 +/− 4.0 and 41.9 +/− 5.0, respectively) and remained virtually unchanged on day 7 (45.6 +/− 10.2). There was widespread cell death in both the TE and ICM as evidenced by fragmenting nuclei, which increased substantially by day 7. These results are compared with the numbers of cells in morphologically abnormal blastocysts and blastocysts derived from abnormally fertilized embryos. The nuclei of arrested embryos were also examined. The number of TE and ICM cells allocated in normally fertilized blastocysts appears to be similar to the numbers allocated in the mouse. Unlike the mouse, however, the proportion of ICM cells remains higher, despite cell death in both lineages.

183 DEVELOPMENT OF PORCINE EMBRYOS MICROINJECTED WITH PORCINE EMBRYONIC GERM CELLS

2006 ◽  
Vol 18 (2) ◽  
pp. 199
Author(s):  
C.-H. Park ◽  
S.-G. Lee ◽  
D.-H. Choi ◽  
M.-G. Kim ◽  
C. K. Lee
Keyword(s):  
Germ Cells ◽  
Fluorescent Protein ◽  
Inner Cell Mass ◽  
Es Cells ◽  
Cell Mass ◽  
Embryonic Stem ◽  
Green Fluorescent Protein Gene ◽  
Cleavage Stage ◽  
Allocation Pattern

Embryonic germ (EG) cells, derived from primordial germ cells in the developing fetus, are similar to embryonic stem (ES) cells in terms of expression pattern of undifferentiated markers and their ability to colonize both the somatic and the germ cell lines following injection into a host blastocyst, which has been proven in mouse. Several studies using porcine EG cells have shown that it is possible to produce somatic chimeras after blastocyst injection. However, not only was the degree of reported chimerism low, but also there has been no report about the fate of injected EG cells in porcine blastocysts. This study was designed to observe the distribution pattern of porcine EG cells in chimeric blastocyst after injection into cleavage-stage porcine embryos. To ascertain development of microinjected porcine embryos with EG cells, 10 to 15 EG cells were injected into cleavage stage of in vitro fertilized embryos and cultured up to blastocyst. Also, porcine EG cells were labeled with DiO (Invitrogen, Carlsbad, CA) on the cell membrane or transfected with green fluorescent protein gene to observe whether the EG cells injected in the host embryo would incorporate into the inner cell mass (ICM) or trophectoderm (TE). Chimeric embryos were produced and allowed to develop into blastocysts to investigate the injected EG cells would come to lie in ICM and/or TE of the blastocyst, by scoring their position. In result, developmental rate was similar in all treatments. In all treatments, EG cells were mainly allocated in both ICM and TE of the chimeric blastocysts. These results suggest that examining the allocation pattern of injected EG cells, maintained pluripotency in vitro, could provide clues of differentiation process in vivo. Furthermore, to enhance the allocation of EG cells into the embryonic lineage, it would be required to optimize the culture condition for EG cells as well as embryos. Further experiment are needed to determine whether the injected EG cells could maintain their properties throughout the environment in the embryonic development in vitro. Table 1. Distribution of the porcine EG cells microinjected into cleavage-stage embryos

scholarly journals Cross-species blastocyst chimerism between nonhuman primates using iPSCs

2019 ◽  
Author(s):  
Morteza Roodgar ◽  
Fabian P. Suchy ◽  
Vivek Bajpai ◽  
Jose G. Viches-Moure ◽  
Joydeep Bhadury ◽  
...  
Keyword(s):  
Rhesus Macaque ◽  
Nonhuman Primates ◽  
Inner Cell Mass ◽  
Cell Mass ◽  
Basic Research ◽  
Human Ipscs ◽  
Mouse Cells ◽  
Induced Pluripotent ◽  
Potential Use

SummaryThrough the production of chimeric animals, induced pluripotent stem cells (iPSCs) can generate personalized organs with diverse applications for both basic research and translational medicine. This concept was first validated in rodents by forming a rat pancreas in mice and vice versa. However, the potential use of human iPSCs to generate xenogenic organs in other species is technically and ethically difficult. Recognizing these concerns, we explored the generation of chimeric nonhuman primates (NHP) embryos, by injecting either chimpanzee or pig-tailed macaque iPSCs into rhesus macaque embryos. We first derived iPSCs from chimpanzees and pig-tailed macaques. We found that the chimpanzee iPSCs mixed well with human iPSCs duringin vitroco-culture and differentiation. The differentiation of mixed human and chimpanzee iPSCs formed functioning cardiomyocyte layers in vitro, whereas human or chimpanzee iPSC mixed with pig-tailed macaque or mouse cells do not; these results indicate that chimpanzee and human cells are closely related in function. Considering the ethical aspects of injecting human iPSCs into nonhuman primate blastocysts, we tested whether chimpanzee iPSCs injected into 99 macaque 5-day-old embryos formed cross-species chimeras two days after injection. Strikingly, the chimpanzee iPSCs survived, proliferated and integrated near the inner cell mass (ICM) of rhesus macaque embryos. These findings highlight the broad potential of primate iPSCs in forming cross-species chimeras beyond rodents and provides a foundational basis for organ generation using human iPSCs.

scholarly journals Pre-Implantation Mouse Embryos Cultured In Vitro under Different Oxygen Concentrations Show Altered Ultrastructures

2020 ◽  
Vol 17 (10) ◽  
pp. 3384
Author(s):  
Manuel Belli ◽  
Paolo Rinaudo ◽  
Maria Grazia Palmerini ◽  
Elena Ruggeri ◽  
Sevastiani Antonouli ◽  
...  
Keyword(s):  
Assisted Reproductive Technologies ◽  
Inner Cell Mass ◽  
Culture Media ◽  
Cell Mass ◽  
Reproductive Technologies ◽  
Mouse Embryos ◽  
Human Embryos ◽  
Fertilization In Vitro ◽  
Vitro Fertilization

Assisted Reproductive Technologies routinely utilize different culture media and oxygen (O2) concentrations to culture human embryos. Overall, embryos cultured under physiological O2 tension (5%) have improved development compared to embryos cultured under atmospheric O2 conditions (20%). The mechanisms responsible for this remain unclear. This study aimed to evaluate the effect of physiologic (5%) or atmospheric O2 (20%) tension on the microscopic ultrastructure of pre-implantation mouse embryos using Transmission Electron Microscopy (TEM). Embryos flushed out of the uterus after natural mating were used as the control. For use as the control, 2-cells, 4-cells, morulae, and blastocysts were flushed out of the uterus after natural fertilization. In vitro fertilization (IVF) was performed using potassium simplex optimized medium (KSOM) under different O2 tensions (5% and 20%) until the blastocyst stage. After collection, embryos were subjected to the standard preparative for light microscopy (LM) and TEM. We found that culture in vitro under 5% and 20% O2 results in an increase of vacuolated shaped mitochondria, cytoplasmic vacuolization and presence of multi-vesicular bodies at every embryonic stage. In addition, blastocysts generated by IVF under 5% and 20% O2 showed a lower content of heterochromatin, an interruption of the trophectodermal and inner cell mass cell membranes, an increased density of residual bodies, and high levels of glycogen granules in the cytoplasm. In conclusion, this study suggests that in vitro culture, particularly under atmospheric O2 tension, causes stage-specific changes in preimplantation embryo ultrastructure. In addition, atmospheric (20%) O2 is associated with increased alterations in embryonic ultrastructure; these changes may explain the reduced embryonic development of embryos cultured with 20% O2.

Use of time-lapse monitoring in medically assisted reproduction treatments: a mini-review

Zygote ◽  
2020 ◽  
pp. 1-9 ◽  
Author(s):  
Romualdo Sciorio
Keyword(s):  
Inner Cell Mass ◽  
Cell Mass ◽  
Digital Camera ◽  
Time Lapse ◽  
Complete Sequence ◽  
Use Of Time ◽  
Inter Observer Variability ◽  
Potential Benefits ◽  
Integrated Software

Summary During human in vitro culture, a morphological microscope analysis is normally performed to select the best embryo to transfer, with the hope of obtaining a successful pregnancy. The morphological evaluation may combine number and size of blastomeres, fragmentation, multinucleation, blastocyst expansion, inner-cell mass and trophectoderm appearance. However, standard microscopy evaluation involves the removal of the embryos from the incubator, exposing them to changes in pH, temperature, and oxygen level. Additionally, morphological assessments might include high inter-observer variability. Recently, continuous embryo culture using time-lapse monitoring (TLM) has allowed embryologists to analyse the dynamic and morphokinetic events of embryo development and, based on that, the embryologist is able to scrutinize the complete sequence of embryonic evolution, from fertilization to the blastocyst formation. Therefore, TLM allows an uninterrupted culture condition, reducing the need to remove embryos from the incubator. The monitoring system is normally composed of a standard incubator with an integrated microscope coupled to a digital camera, which is able to collect images at regular times, and subsequently processed into video. These data can be annotated and analyzed using an integrated software, therefore this allows embryologists to facilitate the process of embryo selection for transfer. The main aim of this paper is to discuss the potential benefits and uses of the TLM in the embryology laboratory.

scholarly journals Single-cell analysis of human embryos reveals diverse patterns of aneuploidy and mosaicism

2020 ◽  
Author(s):  
Margaret R. Starostik ◽  
Olukayode A. Sosina ◽  
Rajiv C. McCoy
Keyword(s):  
Single Cell ◽  
Stress Responses ◽  
Inner Cell Mass ◽  
Cell Mass ◽  
Preimplantation Embryos ◽  
Chromosomal Mosaicism ◽  
Human Embryos ◽  
Published Data ◽  
Aneuploid Cell ◽  
Multiple Biopsies

AbstractLess than half of human zygotes survive to live birth, primarily due to aneuploidies of meiotic or mitotic origin. Mitotic errors lead to chromosomal mosaicism, defined by multiple cell lineages with distinct chromosome complements. The incidence and fitness consequences of chromosomal mosaicism in human embryos remain controversial, with most previous studies based on bulk DNA assays or comparisons of multiple biopsies of a few embryonic cells. Single-cell genomic data provide an opportunity to quantify mosaicism on an embryo-wide scale. To this end, we extended an approach to infer aneuploidies based on chromosome dosage-associated changes in gene expression by integrating signatures of allelic imbalance. We applied this method to published single-cell RNA sequencing data from 74 disaggregated human embryos, spanning the morula to blastocyst stages. Our analysis revealed widespread mosaic aneuploidies across preimplantation development, with 59 of 74 (80%) embryos harboring at least one aneuploid cell (1% FDR). By clustering copy number calls, we reconstructed histories of chromosome mis-segregation, distinguishing meiotic and early mitotic errors from those occurring after lineage differentiation. We observed no significant enrichment of aneuploid cells in the trophectoderm compared to the inner cell mass, though we do detect such an enrichment in published data from later post-implantation stages. Finally, we observed that aneuploid cells exhibit upregulation of immune response genes, as well as downregulation of genes involved in proliferation, metabolism, and protein processing, consistent with stress responses previously documented in other stages and systems. Together, our work provides a high-resolution view of aneuploidy in preimplantation embryos and supports the conclusion that low-level mosaicism is a common feature of early human development.

182 FAST STAINING METHODS FOR DIFFERENTIAL STAINING OF INNER CELL MASS AND TROPHECTODERM CELLS OF MAMMALIAN BLASTOCYSTS

2006 ◽  
Vol 18 (2) ◽  
pp. 199
Author(s):  
S. W. Kim ◽  
J.-K. Park ◽  
J.-H. Han ◽  
C. G. Park ◽  
W.-K. Chang
Keyword(s):  
Inner Cell Mass ◽  
Cell Mass ◽  
Time Lapse ◽  
Treatment Method ◽  
Cell Number ◽  
Total Cell ◽  
Differential Staining ◽  
Green Color ◽  
Mixture Treatment

The present study was undertaken to develop a simple differential staining method for inner cell mass (ICM) and trophectoderm (TE) cells of mammalian blastocysts using the permeabilizing agent, saponin, without species-specific antibodies and complements. The nuclei of whole embryos were pre-stained to green by 5 �M SYTO 13 for 10 min. After washing, the green color of TE was turned to red by exposure to 100 �g/mL propidium iodide and 50 to 100 �g/mL saponin solution for 5 to 10 min. To confirm the exactness of staining patterns, the fluorescent nuclei of ICM and TE from mouse, pig, and bovine blastocysts were compared with 3D location by confocal microscopy. By the saponin mixture treatment method, in vitro-cultured mouse, pig, and bovine blastocysts were shown to have an ICM:TE ratio of 1:2.5, 1:4.5, and 1:3.6, with an average total cell number of 78 � 14 (n = 45), 65 � 18 (n = 49), and 150 � 20 (n = 45), respectively. Although a few TE cells were stained to a yellowish-green color, the successful protection of the green color of ICM depended on the exposure time of blastocysts to the saponin mixture. The total time lapse of the procedure did not exceed 1 h. These results indicate that saponin could be used as a practical substitute for special antibodies and complements. So this differential staining for examining the ICM:TE ratio and the total cell count of mammalian blastocysts would be a fast and reliable method.

scholarly journals A Preclinical Evaluation towards the Clinical Application of Oxygen Consumption Measurement by CERMs by a Mouse Chimera Model

2019 ◽  
Vol 20 (22) ◽  
pp. 5650
Author(s):  
Takashi Kuno ◽  
Masahito Tachibana ◽  
Ayako Fujimine-Sato ◽  
Misaki Fue ◽  
Keiko Higashi ◽  
...  
Keyword(s):  
Oxygen Consumption ◽  
Inner Cell Mass ◽  
Cell Mass ◽  
Human Embryos ◽  
Embryo Morphology ◽  
Vitro Fertilization ◽  
Cell Numbers ◽  
Mitochondrial Dna Copy Number ◽  
Future Fertility

We have developed an automated device for the measurement of oxygen consumption rate (OCR) called Chip-sensing Embryo Respiratory Measurement system (CERMs). To verify the safety and the significance of the OCR measurement by CERMs, we conducted comprehensive tests using a mouse model prior to clinical trials in a human in vitro fertilization (IVF) program. Embryo transfer revealed that the OCR measured by CERMs did not compromise the full-term development of mice or their future fertility, and was positively correlated with adenosine triphosphate (ATP) production and the mitochondrial membrane potential (ΔΨm), thereby indirectly reflecting mitochondrial oxidative phosphorylation (OXPHOS) activity. We demonstrated that the OCR is independent of embryo morphology (the size) and number of mitochondria (mitochondrial DNA copy number). The OCR correlated with the total cell numbers, whereas the inner cell mass (ICM) cell numbers and the fetal developmental rate were not. Thus, the OCR may serve as an indicator of the numbers of trophectoderm (TE) cells, rather than number or quality of ICM cells. However, implantation ability was neither correlated with the OCR, nor the embryo size in this model. This can probably be attributed to the limitation that chimeric embryos contain non-physiological high TE cells counts that are beneficial for implantation. CERMs can be safely employed in clinical IVF owing to it being a safe, highly effective, non-invasive, accurate, and quantitative tool for OCR measurement. Utilization of CERMs for clinical testing of human embryos would provide further insights into the nature of oxidative metabolism and embryonic viability.

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