The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Robert Lanza - One of the best experts on this subject based on the ideXlab platform.
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human embryonic stem cell lines derived from single blastomeres
Nature, 2006Co-Authors: Irina Klimanskaya, Young Gie Chung, Sandy Becker, Robert LanzaAbstract:The derivation of human embryonic stem (hES) cells currently requires the destruction of ex utero Embryos. A previous study in mice indicates that it might be possible to generate embryonic stem (ES) cells using a single-cell biopsy similar to that used in preimplantation genetic diagnosis (PGD), which does not interfere with the embryo's developmental potential. By growing the single blastomere overnight, the resulting cells could be used for both genetic testing and stem cell derivation without affecting the clinical outcome of the procedure. Here we report a series of ten separate experiments demonstrating that hES cells can be derived from single blastomeres. In this proof-of-principle study, multiple biopsies were taken from each embryo using micromanipulation techniques and none of the biopsied Embryos were allowed to develop in culture. Nineteen ES-cell-like outgrowths and two stable hES cell lines were obtained. The latter hES cell lines maintained undifferentiated proliferation for more than eight months, and showed normal karyotype and expression of markers of pluripotency, including Oct-4, SSEA-3, SSEA-4, TRA-1-60, TRA-1-81, nanog and alkaline phosphatase. These cells retained the potential to form derivatives of all three embryonic germ layers both in vitro and in teratomas. The ability to create new stem cell lines and therapies without destroying Embryos would address the ethical concerns of many, and allow the generation of matched tissue for children and siblings born from transferred PGD Embryos.
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embryonic and extraembryonic stem cell lines derived from single mouse blastomeres
Nature, 2006Co-Authors: Young Gie Chung, Irina Klimanskaya, Sandy Becker, Robert Lanza, Joel Marh, Shijiang Lu, Julie Johnson, Lorraine F MeisnerAbstract:The usual methods for establishing human embryonic stem cell lines are controversial as Embryos are destroyed in the process. Two papers in this issue present different means of deriving such cells from mice without the loss of a cloned embryo with potential to develop. Meissner and Jaenisch describe a proof-of-principle experiment in mice based on altered nuclear transfer (ANT), a process that creates blastocysts unable to implant in the uterus. The new technique involves blocking the Cdx2 gene, but as Cdx2 might be needed for therapeutic strategies using these cells, the gene knockout is made reversible and Cdx2 can be turned back on once an embryonic stem-cell culture is established. ANT is one alternative being discussed in US Congress hearings on the possible use of NIH funds for stem-cell research (tinyurl.com/dhwvx). Chung et al. describe a new way of deriving mouse embryonic stem cell lines that does not disrupt the embryo's ability to implant into the womb and develop. This procedure is based on pre-implantation genetic diagnosis (PGD) as used in fertility treatments, where Embryos are screened for genetic defects. If healthy, they are then implanted into the uterus and develop normally. If the procedure can be transferred to human Embryos already undergoing PGD, it may be possible to create banks of human embryonic stem cell lines without additional risk to the Embryos. The most basic objection to human embryonic stem (ES) cell research is rooted in the fact that ES cell derivation deprives Embryos of any further potential to develop into a complete human being1,2. ES cell lines are conventionally isolated from the inner cell mass of blastocysts3,4,5 and, in a few instances, from cleavage stage Embryos6,7,8,9. So far, there have been no reports in the literature of stem cell lines derived using an approach that does not require embryo destruction. Here we report an alternative method of establishing ES cell lines—using a technique of single-cell embryo biopsy similar to that used in pre-implantation genetic diagnosis of genetic defects10—that does not interfere with the developmental potential of Embryos. Five putative ES and seven trophoblast stem (TS) cell lines were produced from single blastomeres, which maintained normal karyotype and markers of pluripotency or TS cells for up to more than 50 passages. The ES cells differentiated into derivatives of all three germ layers in vitro and in teratomas, and showed germ line transmission. Single-blastomere-biopsied Embryos developed to term without a reduction in their developmental capacity. The ability to generate human ES cells without the destruction of ex utero Embryos would reduce or eliminate the ethical concerns of many.
Thierry Voet - One of the best experts on this subject based on the ideXlab platform.
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principles guiding embryo selection following genome wide haplotyping of preimplantation Embryos
Human Reproduction, 2017Co-Authors: Eftychia Dimitriadou, Cindy Melotte, Sophie Debrock, Masoud Zamani Esteki, Kris Dierickx, Thierry Voet, Koen Devriendt, Thomy De Ravel, Eric LegiusAbstract:STUDY QUESTION How to select and prioritize Embryos during PGD following genome-wide haplotyping? SUMMARY ANSWER In addition to genetic disease-specific information, the embryo selected for transfer is based on ranking criteria including the existence of mitotic and/or meiotic aneuploidies, but not carriership of mutations causing recessive disorders. WHAT IS KNOWN ALREADY Embryo selection for monogenic diseases has been mainly performed using targeted disease-specific assays. Recently, these targeted approaches are being complemented by generic genome-wide genetic analysis methods such as karyomapping or haplarithmisis, which are based on genomic haplotype reconstruction of cell(s) biopsied from Embryos. This provides not only information about the inheritance of Mendelian disease alleles but also about numerical and structural chromosome anomalies and haplotypes genome-wide. Reflections on how to use this information in the diagnostic laboratory are lacking. STUDY DESIGN, SIZE, DURATION We present the results of the first 101 PGD cycles (373 Embryos) using haplarithmisis, performed in the Centre for Human Genetics, UZ Leuven. The questions raised were addressed by a multidisciplinary team of clinical geneticist, fertility specialists and ethicists. PARTICIPANTS/MATERIALS, SETTING, METHODS Sixty-three couples enrolled in the genome-wide haplotyping-based PGD program. Families presented with either inherited genetic variants causing known disorders and/or chromosomal rearrangements that could lead to unbalanced translocations in the offspring. MAIN RESULTS AND THE ROLE OF CHANCE Embryos were selected based on the absence or presence of the disease allele, a trisomy or other chromosomal abnormality leading to known developmental disorders. In addition, morphologically normal Day 5 Embryos were prioritized for transfer based on the presence of other chromosomal imbalances and/or carrier information. LIMITATIONS, REASONS FOR CAUTION Some of the choices made and principles put forward are specific for cleavage-stage-based genetic testing. The proposed guidelines are subject to continuous update based on the accumulating knowledge from the implementation of genome-wide methods for PGD in many different centers world-wide as well as the results of ongoing scientific research. WIDER IMPLICATIONS OF THE FINDINGS Our embryo selection principles have a profound impact on the organization of PGD operations and on the information that is transferred among the genetic unit, the fertility clinic and the patients. These principles are also important for the organization of pre- and post-counseling and influence the interpretation and reporting of preimplantation genotyping results. As novel genome-wide approaches for embryo selection are revolutionizing the field of reproductive genetics, national and international discussions to set general guidelines are warranted. STUDY FUNDING/COMPETING INTEREST(S) The European Union's Research and Innovation funding programs FP7-PEOPLE-2012-IAPP SARM: 324509 and Horizon 2020 WIDENLIFE: 692065 to J.R.V., T.V., E.D. and M.Z.E. J.R.V., T.V. and M.Z.E. have patents ZL910050-PCT/EP2011/060211-WO/2011/157846 ('Methods for haplotyping single cells') with royalties paid and ZL913096-PCT/EP2014/068315-WO/2015/028576 ('Haplotyping and copy-number typing using polymorphic variant allelic frequencies') with royalties paid, licensed to Cartagenia (Agilent technologies). J.R.V. also has a patent ZL91 2076-PCT/EP20 one 3/070858 ('High throughout genotyping by sequencing') with royalties paid. TRIAL REGISTRATION NUMBER N/A.
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what next for preimplantation genetic screening high mitotic chromosome instability rate provides the biological basis for the low success rate
Human Reproduction, 2009Co-Authors: Sophie Debrock, Thierry Voet, Evelyne Vanneste, C Melotte, Karen Sermon, Catherine Staessen, I Liebaers, J P Fryns, Thomas DhoogheAbstract:Preimplantation genetic screening is being scrutinized, as recent randomized clinical trials failed to observe the expected significant increase in live birth rates following fluorescence in situ hybridization (FISH)-based screening. Although these randomized clinical trials are criticized on their design, skills or premature stop, it is generally believed that well-designed and well-executed randomized clinical trials would resolve the debate about the potential benefit of preimplantation genetic screening. Since FISH can analyze only a limited number of chromosomal loci, some of the Embryos transferred might be diagnosed as ‘normal’ but in fact be aneuploid for one or more chromosomes not tested. Hence, genome-wide array comparative genome hybridization screening enabling aneuploidy detection of all chromosomes was thought to be a first step toward a better design. We recently showed array screening indeed enables accurate determination of the copy number state of all chromosomes in a single cell. Surprisingly, however, this genome-wide array screening revealed a much higher frequency and complexity of chromosomal aberrations in early Embryos than anticipated, with imbalances in a staggering 90% of all Embryos. The mitotic error rate in cleavage stage Embryos was proven to be higher than the meiotic aneuploidy rate and as a consequence, the genome of a single blastomere is not representative for the genome of the other cells of the embryo. Hence, potentially viable Embryos will be discarded upon screening a single blastomere. This observation provides a biological basis for the failure of the randomized clinical trials to increase baby-take-home rates using FISH on cleavage stage embroys.
Evelyne Vanneste - One of the best experts on this subject based on the ideXlab platform.
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what next for preimplantation genetic screening high mitotic chromosome instability rate provides the biological basis for the low success rate
Human Reproduction, 2009Co-Authors: Sophie Debrock, Thierry Voet, Evelyne Vanneste, C Melotte, Karen Sermon, Catherine Staessen, I Liebaers, J P Fryns, Thomas DhoogheAbstract:Preimplantation genetic screening is being scrutinized, as recent randomized clinical trials failed to observe the expected significant increase in live birth rates following fluorescence in situ hybridization (FISH)-based screening. Although these randomized clinical trials are criticized on their design, skills or premature stop, it is generally believed that well-designed and well-executed randomized clinical trials would resolve the debate about the potential benefit of preimplantation genetic screening. Since FISH can analyze only a limited number of chromosomal loci, some of the Embryos transferred might be diagnosed as ‘normal’ but in fact be aneuploid for one or more chromosomes not tested. Hence, genome-wide array comparative genome hybridization screening enabling aneuploidy detection of all chromosomes was thought to be a first step toward a better design. We recently showed array screening indeed enables accurate determination of the copy number state of all chromosomes in a single cell. Surprisingly, however, this genome-wide array screening revealed a much higher frequency and complexity of chromosomal aberrations in early Embryos than anticipated, with imbalances in a staggering 90% of all Embryos. The mitotic error rate in cleavage stage Embryos was proven to be higher than the meiotic aneuploidy rate and as a consequence, the genome of a single blastomere is not representative for the genome of the other cells of the embryo. Hence, potentially viable Embryos will be discarded upon screening a single blastomere. This observation provides a biological basis for the failure of the randomized clinical trials to increase baby-take-home rates using FISH on cleavage stage embroys.
Wen Yong Li - One of the best experts on this subject based on the ideXlab platform.
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analysis of gene expression in rabbit nuclear transfer Embryos use of single embryo mrna differential display
Development Growth & Differentiation, 2003Co-Authors: Wen Yong Li, Wei Dong Yu, Bing Qi, Yu Ge Wang, Miao Du, Xin He, Qing Xuan ChenAbstract:Lack of or abnormal expression of developmentally important genes is believed to hamper early development of the nuclear transfer (NT) embryo. To identify stage-specific genes in rabbit NT embryo development, mRNA differential display was used to compare the mRNA content of rabbit NT Embryos at different developmental stages, from Metaphase II oocytes to 8–16-cell stage Embryos. Thirty-four zygotic transcripts, which abruptly appeared at the 8–16-cell stage in rabbit NT Embryos, were isolated; 11 of these were potential novel genes with no matches in the current databases. Of the remaining 23, 12 were matched with established sequence tags with functions uncharacterized and the other 11 were homologous to those in the European Molecular Biology Laboratory (EMBL) and GenBank databases. The differential expression of eight of the 34 amplicons were confirmed by reverse Northern blotting, and four positive clones were validated. Previous studies and present data indicated that these three genes were probably related to preimplantation rabbit embryo development.
Sophie Debrock - One of the best experts on this subject based on the ideXlab platform.
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principles guiding embryo selection following genome wide haplotyping of preimplantation Embryos
Human Reproduction, 2017Co-Authors: Eftychia Dimitriadou, Cindy Melotte, Sophie Debrock, Masoud Zamani Esteki, Kris Dierickx, Thierry Voet, Koen Devriendt, Thomy De Ravel, Eric LegiusAbstract:STUDY QUESTION How to select and prioritize Embryos during PGD following genome-wide haplotyping? SUMMARY ANSWER In addition to genetic disease-specific information, the embryo selected for transfer is based on ranking criteria including the existence of mitotic and/or meiotic aneuploidies, but not carriership of mutations causing recessive disorders. WHAT IS KNOWN ALREADY Embryo selection for monogenic diseases has been mainly performed using targeted disease-specific assays. Recently, these targeted approaches are being complemented by generic genome-wide genetic analysis methods such as karyomapping or haplarithmisis, which are based on genomic haplotype reconstruction of cell(s) biopsied from Embryos. This provides not only information about the inheritance of Mendelian disease alleles but also about numerical and structural chromosome anomalies and haplotypes genome-wide. Reflections on how to use this information in the diagnostic laboratory are lacking. STUDY DESIGN, SIZE, DURATION We present the results of the first 101 PGD cycles (373 Embryos) using haplarithmisis, performed in the Centre for Human Genetics, UZ Leuven. The questions raised were addressed by a multidisciplinary team of clinical geneticist, fertility specialists and ethicists. PARTICIPANTS/MATERIALS, SETTING, METHODS Sixty-three couples enrolled in the genome-wide haplotyping-based PGD program. Families presented with either inherited genetic variants causing known disorders and/or chromosomal rearrangements that could lead to unbalanced translocations in the offspring. MAIN RESULTS AND THE ROLE OF CHANCE Embryos were selected based on the absence or presence of the disease allele, a trisomy or other chromosomal abnormality leading to known developmental disorders. In addition, morphologically normal Day 5 Embryos were prioritized for transfer based on the presence of other chromosomal imbalances and/or carrier information. LIMITATIONS, REASONS FOR CAUTION Some of the choices made and principles put forward are specific for cleavage-stage-based genetic testing. The proposed guidelines are subject to continuous update based on the accumulating knowledge from the implementation of genome-wide methods for PGD in many different centers world-wide as well as the results of ongoing scientific research. WIDER IMPLICATIONS OF THE FINDINGS Our embryo selection principles have a profound impact on the organization of PGD operations and on the information that is transferred among the genetic unit, the fertility clinic and the patients. These principles are also important for the organization of pre- and post-counseling and influence the interpretation and reporting of preimplantation genotyping results. As novel genome-wide approaches for embryo selection are revolutionizing the field of reproductive genetics, national and international discussions to set general guidelines are warranted. STUDY FUNDING/COMPETING INTEREST(S) The European Union's Research and Innovation funding programs FP7-PEOPLE-2012-IAPP SARM: 324509 and Horizon 2020 WIDENLIFE: 692065 to J.R.V., T.V., E.D. and M.Z.E. J.R.V., T.V. and M.Z.E. have patents ZL910050-PCT/EP2011/060211-WO/2011/157846 ('Methods for haplotyping single cells') with royalties paid and ZL913096-PCT/EP2014/068315-WO/2015/028576 ('Haplotyping and copy-number typing using polymorphic variant allelic frequencies') with royalties paid, licensed to Cartagenia (Agilent technologies). J.R.V. also has a patent ZL91 2076-PCT/EP20 one 3/070858 ('High throughout genotyping by sequencing') with royalties paid. TRIAL REGISTRATION NUMBER N/A.
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what next for preimplantation genetic screening high mitotic chromosome instability rate provides the biological basis for the low success rate
Human Reproduction, 2009Co-Authors: Sophie Debrock, Thierry Voet, Evelyne Vanneste, C Melotte, Karen Sermon, Catherine Staessen, I Liebaers, J P Fryns, Thomas DhoogheAbstract:Preimplantation genetic screening is being scrutinized, as recent randomized clinical trials failed to observe the expected significant increase in live birth rates following fluorescence in situ hybridization (FISH)-based screening. Although these randomized clinical trials are criticized on their design, skills or premature stop, it is generally believed that well-designed and well-executed randomized clinical trials would resolve the debate about the potential benefit of preimplantation genetic screening. Since FISH can analyze only a limited number of chromosomal loci, some of the Embryos transferred might be diagnosed as ‘normal’ but in fact be aneuploid for one or more chromosomes not tested. Hence, genome-wide array comparative genome hybridization screening enabling aneuploidy detection of all chromosomes was thought to be a first step toward a better design. We recently showed array screening indeed enables accurate determination of the copy number state of all chromosomes in a single cell. Surprisingly, however, this genome-wide array screening revealed a much higher frequency and complexity of chromosomal aberrations in early Embryos than anticipated, with imbalances in a staggering 90% of all Embryos. The mitotic error rate in cleavage stage Embryos was proven to be higher than the meiotic aneuploidy rate and as a consequence, the genome of a single blastomere is not representative for the genome of the other cells of the embryo. Hence, potentially viable Embryos will be discarded upon screening a single blastomere. This observation provides a biological basis for the failure of the randomized clinical trials to increase baby-take-home rates using FISH on cleavage stage embroys.
