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Ivanova AD, Semenova ML. Chromosomal Aberrations As a Biological Phenomenon in Human Embryonic Development. Acta Naturae 2023; 15:27-36. [PMID: 37908766 PMCID: PMC10615189 DOI: 10.32607/actanaturae.25255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Accepted: 08/09/2023] [Indexed: 11/02/2023] Open
Abstract
Frequent chromosomal abnormalities are a distinctive feature of early embryonic development in mammals, especially humans. Aneuploidy is considered as a contributing factor to failed embryo implantation and spontaneous abortions. In the case of chromosomal mosaicism, its effect on the potency of embryos to normally develop has not been sufficiently studied. Although, a significant percentage of chromosomal defects in early human embryos are currently believed to be associated with the features of clinical and laboratory protocols, in this review, we focus on the biological mechanisms associated with chromosomal abnormalities. In particular, we address the main events in oocyte meiosis that affects not only the genetic status of an unfertilized oocyte, but also further embryo viability, and analyze the features of first cleavage divisions and the causes of frequent chromosomal errors in early embryonic development. In addition, we discuss current data on self-correction of the chromosomal status in early embryos.
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Affiliation(s)
- A. D. Ivanova
- Lomonosov Moscow State University, Biological Faculty, Moscow, 119991 Russian Federation
| | - M. L. Semenova
- Lomonosov Moscow State University, Biological Faculty, Moscow, 119991 Russian Federation
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2
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Jacobs K, Doerdelmann C, Krietsch J, González-Acosta D, Mathis N, Kushinsky S, Guarino E, Gómez-Escolar C, Martinez D, Schmid JA, Leary PJ, Freire R, Ramiro AR, Eischen CM, Mendez J, Lopes M. Stress-triggered hematopoietic stem cell proliferation relies on PrimPol-mediated repriming. Mol Cell 2022; 82:4176-4188.e8. [PMID: 36152632 DOI: 10.1016/j.molcel.2022.09.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Revised: 07/01/2022] [Accepted: 09/08/2022] [Indexed: 11/17/2022]
Abstract
Stem cell division is linked to tumorigenesis by yet-elusive mechanisms. The hematopoietic system reacts to stress by triggering hematopoietic stem and progenitor cell (HSPC) proliferation, which can be accompanied by chromosomal breakage in activated hematopoietic stem cells (HSCs). However, whether these lesions persist in their downstream progeny and induce a canonical DNA damage response (DDR) remains unclear. Inducing HSPC proliferation by simulated viral infection, we report that the associated DNA damage is restricted to HSCs and that proliferating HSCs rewire their DDR upon endogenous and clastogen-induced damage. Combining transcriptomics, single-cell and single-molecule assays on murine bone marrow cells, we found accelerated fork progression in stimulated HSPCs, reflecting engagement of PrimPol-dependent repriming, at the expense of replication fork reversal. Ultimately, competitive bone marrow transplantation revealed the requirement of PrimPol for efficient HSC amplification and bone marrow reconstitution. Hence, fine-tuning replication fork plasticity is essential to support stem cell functionality upon proliferation stimuli.
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Affiliation(s)
- Kurt Jacobs
- Institute of Molecular Cancer Research, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Cyril Doerdelmann
- Institute of Molecular Cancer Research, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Jana Krietsch
- Institute of Molecular Cancer Research, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Daniel González-Acosta
- Institute of Molecular Cancer Research, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland; DNA Replication Group, Molecular Oncology Programme, Spanish National Cancer Research Centre (CNIO), Melchor Fernández Almagro 3, 28029 Madrid, Spain
| | - Nicolas Mathis
- Institute of Molecular Cancer Research, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Saul Kushinsky
- Department of Cancer Biology, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, USA
| | - Estrella Guarino
- DNA Replication Group, Molecular Oncology Programme, Spanish National Cancer Research Centre (CNIO), Melchor Fernández Almagro 3, 28029 Madrid, Spain
| | - Carmen Gómez-Escolar
- B Lymphocyte Biology Laboratory, Spanish National Center for Cardiovascular Research (CNIC), Melchor Fernández Almagro 3, 28029 Madrid, Spain
| | - Dolores Martinez
- Flow Cytometry Unit, Biotechnology Programme, Spanish National Cancer Research Centre (CNIO), Melchor Fernández Almagro 3, 28029 Madrid, Spain
| | - Jonas A Schmid
- Institute of Molecular Cancer Research, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Peter J Leary
- Institute of Molecular Cancer Research, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland; Functional Genomic Center Zurich, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Raimundo Freire
- Unidad de Investigación, Hospital Universitario de Canarias, Tenerife, Spain; Instituto de Tecnologías Biomédicas, Universidad de La Laguna, La Laguna, Spain; Universidad Fernando Pessoa Canarias, Las Palmas de Gran Canaria, Spain
| | - Almudena R Ramiro
- B Lymphocyte Biology Laboratory, Spanish National Center for Cardiovascular Research (CNIC), Melchor Fernández Almagro 3, 28029 Madrid, Spain
| | - Christine M Eischen
- Department of Cancer Biology, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, USA
| | - Juan Mendez
- DNA Replication Group, Molecular Oncology Programme, Spanish National Cancer Research Centre (CNIO), Melchor Fernández Almagro 3, 28029 Madrid, Spain.
| | - Massimo Lopes
- Institute of Molecular Cancer Research, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland.
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3
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The mechanisms and clinical application of mosaicism in preimplantation embryos. J Assist Reprod Genet 2019; 37:497-508. [PMID: 31838629 DOI: 10.1007/s10815-019-01656-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Accepted: 12/05/2019] [Indexed: 02/08/2023] Open
Abstract
Embryos containing distinct cell lines are referred to as mosaic embryos, which are considered to be caused by mitotic errors in chromosome segregation during preimplantation development. As the accuracy and resolution of detection techniques improve, more and more mosaic embryos were identified recently. The impacts of mosaic embryos on survival and potential pregnancy outcome have been reported to be diverse in different studies. Because of the universality and clinical significance of mosaicism, it is essential to unravel the mechanisms and consequences with regard to this phenomenon in human pre- and post-implantation embryos. The purpose of this review is to explore the mechanisms, causes of mosaicism, and the development of pre- and post-implantation mosaic embryos in the light of recent emerging data, with the aim of providing new references for clinical applications.
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Tšuiko O, Jatsenko T, Parameswaran Grace LK, Kurg A, Vermeesch JR, Lanner F, Altmäe S, Salumets A. A speculative outlook on embryonic aneuploidy: Can molecular pathways be involved? Dev Biol 2018; 447:3-13. [PMID: 29391166 DOI: 10.1016/j.ydbio.2018.01.014] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Revised: 12/27/2017] [Accepted: 01/22/2018] [Indexed: 01/21/2023]
Abstract
The journey of embryonic development starts at oocyte fertilization, which triggers a complex cascade of events and cellular pathways that guide early embryogenesis. Recent technological advances have greatly expanded our knowledge of cleavage-stage embryo development, which is characterized by an increased rate of whole-chromosome losses and gains, mixoploidy, and atypical cleavage morphokinetics. Embryonic aneuploidy significantly contributes to implantation failure, spontaneous miscarriage, stillbirth or congenital birth defects in both natural and assisted human reproduction. Essentially, early embryo development is strongly determined by maternal factors. Owing to considerable limitations associated with human oocyte and embryo research, the use of animal models is inevitable. However, cellular and molecular mechanisms driving the error-prone early stages of development are still poorly described. In this review, we describe known events that lead to aneuploidy in mammalian oocytes and preimplantation embryos. As the processes of oocyte and embryo development are rigorously regulated by multiple signal-transduction pathways, we explore the putative role of signaling pathways in genomic integrity maintenance. Based on the existing evidence from human and animal data, we investigate whether critical early developmental pathways, like Wnt, Hippo and MAPK, together with distinct DNA damage response and DNA repair pathways can be associated with embryo genomic instability, a question that has, so far, remained largely unexplored.
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Affiliation(s)
- Olga Tšuiko
- Department of Biomedicine, Institute of Bio- and Translational Medicine, University of Tartu, Tartu 50411, Estonia; Competence Centre on Health Technologies, Tartu 50410, Estonia
| | | | - Lalit Kumar Parameswaran Grace
- Department of Women's and Children's Health, Division of Obstetrics and Gynecology, Karolinska Institutet, Karolinska University Hospital, Stockholm 17176, Sweden
| | - Ants Kurg
- Department of Biotechnology, Institute of Molecular and Cell Biology, University of Tartu, Tartu 51010, Estonia
| | - Joris Robert Vermeesch
- Laboratory of Cytogenetics and Genome Research, Center of Human Genetics, KU Leuven, Leuven 3000, Belgium
| | - Fredrik Lanner
- Department of Clinical Science, Intervention, and Technology, Karolinska Institutet, Stockholm 14186, Sweden
| | - Signe Altmäe
- Competence Centre on Health Technologies, Tartu 50410, Estonia; Department of Biochemistry and Molecular Biology, Faculty of Sciences, University of Granada, Granada 18071, Spain.
| | - Andres Salumets
- Department of Biomedicine, Institute of Bio- and Translational Medicine, University of Tartu, Tartu 50411, Estonia; Competence Centre on Health Technologies, Tartu 50410, Estonia; Department of Obstetrics and Gynecology, Institute of Clinical Medicine, University of Tartu, Tartu 51014, Estonia; Department of Obstetrics and Gynecology, University of Helsinki and Helsinki University Hospital, Helsinki 00029, Finland
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Capalbo A, Rienzi L. Mosaicism between trophectoderm and inner cell mass. Fertil Steril 2017; 107:1098-1106. [PMID: 28433375 DOI: 10.1016/j.fertnstert.2017.03.023] [Citation(s) in RCA: 70] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2017] [Accepted: 03/21/2017] [Indexed: 11/28/2022]
Abstract
Defining the actual incidence and prevalence of mosaicism in human blastocysts still remains a difficult task. The small amount of evidence generated by animal and human studies does not support the existence of mechanisms involved in developmental arrest, clonal depletion, or aneuploidy rescue for abnormal cells in euploid/aneuploid embryos during preimplantation development. However, studies in humans are mainly descriptive and lack functional evidence. Understanding the biological mechanisms that beset preimplantation differentiation holds the potential to reveal the role of aneuploidies and gene dosage imbalances in cell fate decision, providing important clues on the origin and evolution of embryonic mosaicism. The evidence on human blastocysts suggests that a mosaic euploid/aneuploid configuration is detected in around 5% of embryos. This figure supports the extremely low level of mosaicism reported in natural and IVF pregnancies. Similarly, the clinical management of patterns consistent with the presence of mosaicism in a trophectoderm biopsy during preimplantation genetic diagnosis cycles (PGD-A) is still a controversial issue. Despite the facts that some contemporary comprehensive chromosomal screening platforms can detect mosaic samples in cell mixture models with variable accuracy and many reproductive genetics laboratories are now routinely including embryonic mosaicism on their genetic reports, a diagnosis of certainty for mosaicism in PGD-A cycles is conceptually impracticable. Indeed, several technical and biological sources of errors clearly exist when trying to estimate mosaicism from a single trophectoderm biopsy in PGD-A cycles and must be understood to adequately guide patients during clinical care.
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Affiliation(s)
- Antonio Capalbo
- GENERA, Centre for Reproductive Medicine, Clinica Valle Giulia, Rome, Italy; GENETYX, Molecular Genetics Laboratory, Vicenza, Italy.
| | - Laura Rienzi
- GENERA, Centre for Reproductive Medicine, Clinica Valle Giulia, Rome, Italy; GENETYX, Molecular Genetics Laboratory, Vicenza, Italy
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Vlismas A, Bletsa R, Mavrogianni D, Mamali G, Pergamali M, Dinopoulou V, Partsinevelos G, Drakakis P, Loutradis D, Kiessling AA. Microarray Analyses Reveal Marked Differences in Growth Factor and Receptor Expression Between 8-Cell Human Embryos and Pluripotent Stem Cells. Stem Cells Dev 2016; 25:160-77. [PMID: 26493868 PMCID: PMC4733324 DOI: 10.1089/scd.2015.0284] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Accepted: 10/22/2015] [Indexed: 11/19/2022] Open
Abstract
Previous microarray analyses of RNAs from 8-cell (8C) human embryos revealed a lack of cell cycle checkpoints and overexpression of core circadian oscillators and cell cycle drivers relative to pluripotent human stem cells [human embryonic stem cells/induced pluripotent stem (hES/iPS)] and fibroblasts, suggesting growth factor independence during early cleavage stages. To explore this possibility, we queried our combined microarray database for expression of 487 growth factors and receptors. Fifty-one gene elements were overdetected on the 8C arrays relative to hES/iPS cells, including 14 detected at least 80-fold higher, which annotated to multiple pathways: six cytokine family (CSF1R, IL2RG, IL3RA, IL4, IL17B, IL23R), four transforming growth factor beta (TGFB) family (BMP6, BMP15, GDF9, ENG), one fibroblast growth factor (FGF) family [FGF14(FH4)], one epidermal growth factor member (GAB1), plus CD36, and CLEC10A. 8C-specific gene elements were enriched (73%) for reported circadian-controlled genes in mouse tissues. High-level detection of CSF1R, ENG, IL23R, and IL3RA specifically on the 8C arrays suggests the embryo plays an active role in blocking immune rejection and is poised for trophectoderm development; robust detection of NRG1, GAB1, -2, GRB7, and FGF14(FHF4) indicates novel roles in early development in addition to their known roles in later development. Forty-four gene elements were underdetected on the 8C arrays, including 11 at least 80-fold under the pluripotent cells: two cytokines (IFITM1, TNFRSF8), five TGFBs (BMP7, LEFTY1, LEFTY2, TDGF1, TDGF3), two FGFs (FGF2, FGF receptor 1), plus ING5, and WNT6. The microarray detection patterns suggest that hES/iPS cells exhibit suppressed circadian competence, underexpression of early differentiation markers, and more robust expression of generic pluripotency genes, in keeping with an artificial state of continual uncommitted cell division. In contrast, gene expression patterns of the 8C embryo suggest that it is an independent circadian rhythm-competent equivalence group poised to signal its environment, defend against maternal immune rejection, and begin the rapid commitment events of early embryogenesis.
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Affiliation(s)
- Antonis Vlismas
- 1 Obstetrics and Gynecology Department of University of Athens, “Alexandra” Maternity Hospital, Athens, Greece
| | - Ritsa Bletsa
- 1 Obstetrics and Gynecology Department of University of Athens, “Alexandra” Maternity Hospital, Athens, Greece
| | - Despina Mavrogianni
- 1 Obstetrics and Gynecology Department of University of Athens, “Alexandra” Maternity Hospital, Athens, Greece
| | - Georgina Mamali
- 1 Obstetrics and Gynecology Department of University of Athens, “Alexandra” Maternity Hospital, Athens, Greece
| | - Maria Pergamali
- 1 Obstetrics and Gynecology Department of University of Athens, “Alexandra” Maternity Hospital, Athens, Greece
| | - Vasiliki Dinopoulou
- 1 Obstetrics and Gynecology Department of University of Athens, “Alexandra” Maternity Hospital, Athens, Greece
- Bedford Research Foundation, Bedford, Massachusetts
| | - George Partsinevelos
- 1 Obstetrics and Gynecology Department of University of Athens, “Alexandra” Maternity Hospital, Athens, Greece
| | - Peter Drakakis
- 1 Obstetrics and Gynecology Department of University of Athens, “Alexandra” Maternity Hospital, Athens, Greece
| | - Dimitris Loutradis
- 1 Obstetrics and Gynecology Department of University of Athens, “Alexandra” Maternity Hospital, Athens, Greece
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Maurer M, Ebner T, Puchner M, Mayer RB, Shebl O, Oppelt P, Duba HC. Chromosomal Aneuploidies and Early Embryonic Developmental Arrest. INTERNATIONAL JOURNAL OF FERTILITY & STERILITY 2015; 9:346-53. [PMID: 26644858 PMCID: PMC4671381 DOI: 10.22074/ijfs.2015.4550] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/20/2013] [Accepted: 05/19/2014] [Indexed: 11/04/2022]
Abstract
BACKGROUND Selecting the best embryo for transfer, with the highest chance of achieving a vital pregnancy, is a major goal in current in vitro fertilization (IVF) technology. The high rate of embryonic developmental arrest during IVF treatment is one of the limitations in achieving this goal. Chromosomal abnormalities are possibly linked with chromosomal arrest and selection against abnormal fertilization products. The objective of this study was to evaluate the frequency and type of chromosomal abnormalities in preimplantation embryos with developmental arrest. MATERIALS AND METHODS This cohort study included blastomeres of embryos with early developmental arrest that were biopsied and analyzed by fluorescence in-situ hybridization (FISH) with probes for chromosomes 13, 16, 18, 21 and 22. Forty-five couples undergoing IVF treatment were included, and 119 arrested embryos were biopsied. All probes were obtained from the Kinderwunsch Zentrum, Linz, Austria, between August 2009 and August 2011. RESULTS Of these embryos, 31.6% were normal for all chromosomes tested, and 68.4% were abnormal. Eleven embryos were uniformly aneuploid, 20 were polyploid, 3 were haploid, 11 displayed mosaicism and 22 embryos exhibited chaotic chromosomal complement. CONCLUSION Nearly 70% of arrested embryos exhibit chromosomal errors, making chromosomal abnormalities a major cause of embryonic arrest and may be a further explanation for the high developmental failure rates during culture of the embryos in the IVF setting.
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Affiliation(s)
- Maria Maurer
- Landes-Frauen-und Kinderklinik Linz, Department of Human Genetics, Krankenhausstraße, Linz, Austria ; Johannes Kepler University, Faculty of Medicine, Linz, Austria
| | - Thomas Ebner
- Johannes Kepler University, Faculty of Medicine, Linz, Austria ; Landes-Frauen-und Kinderklinik Linz, Department of Gynecological Endocrinology and Kinderwunsch Zentrum Linz, Krankenhausstraße, Linz, Austria
| | - Manuela Puchner
- Johannes Kepler University, Faculty of Medicine, Linz, Austria ; Landes-Frauen-und Kinderklinik Linz, Department of Gynecological Endocrinology and Kinderwunsch Zentrum Linz, Krankenhausstraße, Linz, Austria
| | - Richard Bernhard Mayer
- Johannes Kepler University, Faculty of Medicine, Linz, Austria ; Landes-Frauen-und Kinderklinik Linz, Department of Gynecological Endocrinology and Kinderwunsch Zentrum Linz, Krankenhausstraße, Linz, Austria
| | - Omar Shebl
- Johannes Kepler University, Faculty of Medicine, Linz, Austria ; Landes-Frauen-und Kinderklinik Linz, Department of Gynecological Endocrinology and Kinderwunsch Zentrum Linz, Krankenhausstraße, Linz, Austria
| | - Peter Oppelt
- Johannes Kepler University, Faculty of Medicine, Linz, Austria ; Landes-Frauen-und Kinderklinik Linz, Department of Gynecological Endocrinology and Kinderwunsch Zentrum Linz, Krankenhausstraße, Linz, Austria
| | - Hans-Christoph Duba
- Landes-Frauen-und Kinderklinik Linz, Department of Human Genetics, Krankenhausstraße, Linz, Austria ; Johannes Kepler University, Faculty of Medicine, Linz, Austria
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Zusätzliche Verfahren zur Verbesserung der Implantationsrate. GYNAKOLOGISCHE ENDOKRINOLOGIE 2014. [DOI: 10.1007/s10304-013-0604-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Abstract
A response to the editorial "On patenting time and other natural phenomenon" by Jacques Cohen.
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Machtinger R, Racowsky C. Morphological systems of human embryo assessment and clinical evidence. Reprod Biomed Online 2012; 26:210-21. [PMID: 23352813 DOI: 10.1016/j.rbmo.2012.10.021] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2012] [Revised: 10/16/2012] [Accepted: 10/16/2012] [Indexed: 10/27/2022]
Abstract
Success rates with IVF have improved remarkably since the procedure was first established for clinical use with the first successful birth in 1978. The main goals today are to perform single-embryo transfer in order to prevent multiple pregnancies and achieve higher overall pregnancy rates. However, the ability to identify the most viable embryo in a cohort remains a challenge despite the numerous scoring systems currently in use. Clinicians still depend on developmental rate and morphological assessment using light microscopy as the first-line approach for embryo selection. Active research in the field involves developing non-invasive methods for scoring embryos and ranking them according to their ability to implant and give rise to a healthy birth. Current attention is particularly being focused on time-lapse evaluation. Available data from preliminary studies indicate that these systems are safe;prospective data now need to be collected to determine whether these methods do improve implantation rates. This review gives brief consideration to the use of morphological evaluations in assisted reproduction treatment, discusses the types of embryo scoring,digital imaging and biometric approaches currently in use and comments on future developments for embryo evaluation.
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Affiliation(s)
- Ronit Machtinger
- Department of Obstetrics, Gynecology and Reproductive Biology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States
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HLINKA D, KAĽATOVÁ B, UHRINOVÁ I, DOLINSKÁ S, RUTAROVÁ J, ŘEZÁČOVÁ J, LAZAROVSKÁ S, DUDÁŠ M. Time-Lapse Cleavage Rating Predicts Human Embryo Viability. Physiol Res 2012; 61:513-25. [DOI: 10.33549/physiolres.932287] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Chronology of three consecutive mitotic events in human pre-implantation embryos was examined by time-lapse imaging. In zygotes producing well-formed and pregnancy-yielding expanded blastocysts, uniform time-patterning of cleavage clusters (c) and interphases (i) was revealed: i2=11±1, i3=15±1, i4=23±1 h / c2=15±5, c3=40±10, c4=55±15 min. Oppositely, shortened or prolonged durations of one or more cell cycles were strongly predictive of poor implantation and development. Furthermore, trichotomic mitosis was discovered in 17 % of cases - zygotes cleaved into 3 blastomeres and 2-cell embryos into 5-6 cells (instead of normal 2 and 4). During conventional clinical assessment, such embryos are indistinguishable from normal, often considered just-in-course of the next cell cycle. Only detailed time-lapse monitoring paced at 10-minute intervals had proven all these embryos to be absolutely unviable, even in rare cases when they reduced their hypercellularity to normal cell counts via cell-cell fusion. Overall, we demonstrate that time-lapse embryo cleavage rating (ECR) as a standalone diagnostic procedure allows for effective identification of viable early embryos with 90 % specificity, while elimination of good-looking but unviable embryos can be assumed with a specificity of 100 %. Thus, making this non-invasive and contactless approach worth of addition to routine embryo screening in clinical IVF programs.
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Affiliation(s)
| | | | | | | | | | | | | | - M. DUDÁŠ
- Fetal Medicine Program, Department of Cell Biology, Safarik University, Kosice, Slovakia
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