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Advanced maternal age perturbs mouse embryo development and alters the phenotype of derived embryonic stem cells. J Dev Orig Health Dis 2021; 13:395-405. [PMID: 34193331 DOI: 10.1017/s2040174421000325] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Advanced maternal age (AMA) is known to reduce fertility, increases aneuploidy in oocytes and early embryos and leads to adverse developmental consequences which may associate with offspring lifetime health risks. However, investigating underlying effects of AMA on embryo developmental potential is confounded by the inherent senescence present in maternal body systems further affecting reproductive success. Here, we describe a new model for the analysis of early developmental mechanisms underlying AMA by the derivation and characterisation of mouse embryonic stem cell (mESC-like) lines from naturally conceived embryos. Young (7-8 weeks) and Old (7-8 months) C57BL/6 female mice were mated with young males. Preimplantation embryos from Old dams displayed developmental retardation in blastocyst morphogenesis. mESC lines established from these blastocysts using conventional techniques revealed differences in genetic, cellular and molecular criteria conserved over several passages in the standardised medium. mESCs from embryos from AMA dams displayed increased incidence of aneuploidy following Giemsa karyotyping compared with those from Young dams. Moreover, AMA caused an altered pattern of expression of pluripotency markers (Sox2, OCT4) in mESCs. AMA further diminished mESC survival and proliferation and reduced the expression of cell proliferation marker, Ki-67. These changes coincided with altered expression of the epigenetic marker, Dnmt3a and other developmental regulators in a sex-dependent manner. Collectively, our data demonstrate the feasibility to utilise mESCs to reveal developmental mechanisms underlying AMA in the absence of maternal senescence and with reduced animal use.
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2
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Grzybek M, Golonko A, Walczak M, Lisowski P. Epigenetics of cell fate reprogramming and its implications for neurological disorders modelling. Neurobiol Dis 2016; 99:84-120. [PMID: 27890672 DOI: 10.1016/j.nbd.2016.11.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Revised: 11/03/2016] [Accepted: 11/21/2016] [Indexed: 02/06/2023] Open
Abstract
The reprogramming of human induced pluripotent stem cells (hiPSCs) proceeds in a stepwise manner with reprogramming factors binding and epigenetic composition changes during transition to maintain the epigenetic landscape, important for pluripotency. There arises a question as to whether the aberrant epigenetic state after reprogramming leads to epigenetic defects in induced stem cells causing unpredictable long term effects in differentiated cells. In this review, we present a comprehensive view of epigenetic alterations accompanying reprogramming, cell maintenance and differentiation as factors that influence applications of hiPSCs in stem cell based technologies. We conclude that sample heterogeneity masks DNA methylation signatures in subpopulations of cells and thus believe that beside a genetic evaluation, extensive epigenomic screening should become a standard procedure to ensure hiPSCs state before they are used for genome editing and differentiation into neurons of interest. In particular, we suggest that exploitation of the single-cell composition of the epigenome will provide important insights into heterogeneity within hiPSCs subpopulations to fast forward development of reliable hiPSC-based analytical platforms in neurological disorders modelling and before completed hiPSC technology will be implemented in clinical approaches.
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Affiliation(s)
- Maciej Grzybek
- Faculty of Veterinary Medicine, University of Life Sciences in Lublin, Akademicka 12, 20-950 Lublin, Poland; Department of Molecular Biology, Institute of Genetics and Animal Breeding, Polish Academy of Sciences, Jastrzębiec, Postępu 36A, 05-552 Magdalenka, Poland.
| | - Aleksandra Golonko
- Department of Biotechnology, Faculty of Civil and Environmental Engineering, Bialystok University of Technology, Wiejska 45E, 15-351 Bialystok, Poland.
| | - Marta Walczak
- Department of Animal Behavior, Institute of Genetics and Animal Breeding, Polish Academy of Sciences, Jastrzębiec, Postępu 36A, 05-552 Magdalenka, Poland.
| | - Pawel Lisowski
- Department of Molecular Biology, Institute of Genetics and Animal Breeding, Polish Academy of Sciences, Jastrzębiec, Postępu 36A, 05-552 Magdalenka, Poland; iPS Cell-Based Disease Modelling Group, Max Delbrück Center for Molecular Medicine (MDC) in the Helmholtz Association, Robert-Rössle-Str. 10, 13092 Berlin, Germany.
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Abstract
Vertebrate genomes are highly methylated at cytosine residues in CpG sequences. CpG
methylation plays an important role in epigenetic gene silencing and genome stability.
Compared with other epigenetic modifications, CpG methylation is thought to be relatively
stable; however, it is sometimes affected by environmental changes, leading to epigenetic
instability and disease. CpG methylation is reversible and regulated by DNA
methyltransferases and demethylases including ten-eleven translocation. Here, we discuss
CpG methylation instability and the regulation of CpG methylation by DNA
methyltransferases and ten-eleven translocation in pluripotent stem cells.
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Affiliation(s)
- Takuro Horii
- Laboratory of Genome Science, Biosignal Genome Resource Center, Institute for Molecular and Cellular Regulation, Gunma University, Gunma 371-8512, Japan
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Simbulan RK, Di Santo M, Liu X, Lin W, Donjacour A, Maltepe E, Shenoy A, Borini A, Rinaudo P. Embryonic stem cells derived from in vivo or in vitro-generated murine blastocysts display similar transcriptome and differentiation potential. PLoS One 2015; 10:e0117422. [PMID: 25723476 PMCID: PMC4344309 DOI: 10.1371/journal.pone.0117422] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Accepted: 12/22/2014] [Indexed: 11/23/2022] Open
Abstract
The use of assisted reproductive technologies (ART) such as in vitro fertilization (IVF) has resulted in the birth of more than 5 million children. While children conceived by these technologies are generally healthy, there is conflicting evidence suggesting an increase in adult-onset complications like glucose intolerance and high blood pressure in IVF children. Animal models indicate similar potential risks. It remains unclear what molecular mechanisms may be operating during in vitro culture to predispose the embryo to these diseases. One of the limitations faced by investigators is the paucity of the material in the preimplantation embryo to test for molecular analysis. To address this problem, we generated mouse embryonic stem cells (mESC) from blastocysts conceived after natural mating (mESCFB) or after IVF, using optimal (KSOM + 5% O2; mESCKAA) and suboptimal (Whitten’s Medium, + 20% O2, mESCWM) conditions. All three groups of embryos showed similar behavior during both derivation and differentiation into their respective mESC lines. Unsupervised hierarchical clustering of microarray data showed that blastocyst culture does not affect the transcriptome of derived mESCs. Transcriptomic changes previously observed in the inner cell mass (ICM) of embryos derived in the same conditions were not present in mESCs, regardless of method of conception or culture medium, suggesting that mESC do not fully maintain a memory of the events occurring prior to their derivation. We conclude that the fertilization method or culture media used to generate blastocysts does not affect differentiation potential, morphology and transcriptome of mESCs.
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Affiliation(s)
- Rhodel K. Simbulan
- Department of Obstetrics, Gynecology and Reproductive Sciences, University of California San Francisco, San Francisco, California, United States of America
| | - Marlea Di Santo
- Department of Obstetrics, Gynecology and Reproductive Sciences, University of California San Francisco, San Francisco, California, United States of America
- Tecnobios Procreazione, Bologna, Italy
| | - Xiaowei Liu
- Department of Obstetrics, Gynecology and Reproductive Sciences, University of California San Francisco, San Francisco, California, United States of America
| | - Wingka Lin
- Department of Obstetrics, Gynecology and Reproductive Sciences, University of California San Francisco, San Francisco, California, United States of America
| | - Annemarie Donjacour
- Department of Obstetrics, Gynecology and Reproductive Sciences, University of California San Francisco, San Francisco, California, United States of America
- Department of Anatomy, University of California San Francisco, San Francisco, California, United States of America
| | - Emin Maltepe
- Department of Pediatrics, University of California San Francisco, San Francisco, California, United States of America
| | - Archana Shenoy
- Department of Urology, University of California San Francisco, San Francisco, California, United States of America
| | | | - Paolo Rinaudo
- Department of Obstetrics, Gynecology and Reproductive Sciences, University of California San Francisco, San Francisco, California, United States of America
- * E-mail:
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5
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Bakhtari A, Rahmani HR, Bonakdar E, Jafarpour F, Asgari V, Hosseini SM, Hajian M, Edriss MA, Nasr-Esfahani MH. The interfering effects of superovulation and vitrification upon some important epigenetic biomarkers in mouse blastocyst. Cryobiology 2014; 69:419-27. [DOI: 10.1016/j.cryobiol.2014.09.379] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Revised: 09/22/2014] [Accepted: 09/22/2014] [Indexed: 01/18/2023]
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6
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Ramos-Ibeas P, Pericuesta E, Fernández-González R, Gutiérrez-Adán A, Ramírez MÁ. Germ-cell culture conditions facilitate the production of mouse embryonic stem cells. Mol Reprod Dev 2014; 81:794-804. [PMID: 24861201 DOI: 10.1002/mrd.22346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Accepted: 05/21/2014] [Indexed: 11/10/2022]
Abstract
The derivation of embryonic stem-cell (ESC) lines from blastocysts is a very inefficient process. Murine ESCs are thought to arise from epiblast cells that are already predisposed to a primordial-germ-cell fate. During the process of ESC derivation from B6D2 F1 hybrid mice, if we first culture the embryo from the two-cell stage in medium supplemented with LIF, we improve the quality of the blastocyst. When the blastocyst is then cultured in a germ-line stem-cell culture medium (GSCm), we are able to more efficiently (28.3%) obtain quality ESC lines that have a normal karyotype, proper degree of chimerism, and exhibit germ-line transmission when microinjected into blastocysts. Although germ-cell-specific genes were expressed in all culture medium conditions, GSCm did not shift the transcriptome towards germ-cell specification. A correlation was further observed between ESC derivation efficiency and the expression of some imprinted genes and retrotransposable elements. In conclusion, the combination of LIF supplementation followed by culture in GSCm establishes a higher efficiency method for ESC derivation.
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7
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Fauser BCJM, Devroey P, Diedrich K, Balaban B, Bonduelle M, Delemarre-van de Waal HA, Estella C, Ezcurra D, Geraedts JPM, Howles CM, Lerner-Geva L, Serna J, Wells D. Health outcomes of children born after IVF/ICSI: a review of current expert opinion and literature. Reprod Biomed Online 2013; 28:162-82. [PMID: 24365026 DOI: 10.1016/j.rbmo.2013.10.013] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2012] [Revised: 10/03/2013] [Accepted: 10/08/2013] [Indexed: 01/28/2023]
Abstract
The Sixth Evian Annual Reproduction (EVAR) Workshop Group Meeting was held to evaluate the impact of IVF/intracytoplasmic sperm injection on the health of assisted-conception children. Epidemiologists, reproductive endocrinologists, embryologists and geneticists presented data from published literature and ongoing research on the incidence of genetic and epigenetic abnormalities and congenital malformations in assisted-conception versus naturally conceived children to reach a consensus on the reasons for potential differences in outcomes between these two groups. IVF-conceived children have lower birthweights and higher peripheral fat, blood pressure and fasting glucose concentrations than controls. Growth, development and cognitive function in assisted-conception children are similar to controls. The absolute risk of imprinting disorders after assisted reproduction is less than 1%. A direct link between assisted reproduction and health-related outcomes in assisted-conception children could not be established. Women undergoing assisted reproduction are often older, increasing the chances of obtaining abnormal gametes that may cause deviations in outcomes between assisted-conception and naturally conceived children. However, after taking into account these factors, it is not clear to what extent poorer outcomes are due to the assisted reproduction procedures themselves. Large-scale, multicentre, prospective epidemiological studies are needed to investigate this further and to confirm long-term health consequences in assisted-conception children. Assisted reproduction treatment is a general term used to describe methods of achieving pregnancy by artificial means and includes IVF and sperm implantation. The effect of assisted reproduction treatment on the health of children born using these artificial methods is not fully understood. In April 2011, fertility research experts met to give presentations based on research in this area and to look carefully at the evidence for the effects of assisted reproduction treatment on children's health. The purpose of this review was to reach an agreement on whether there are differences in the health of assisted-conception children with naturally conceived children. The researchers discovered no increased risk in birth defects in assisted-conception children compared with naturally conceived children. They found that IVF-conceived children have lower birth weights and higher fat under the skin, higher blood pressure and higher fasting glucose concentrations than naturally conceived children; however, growth, development and cognitive function are similar between groups. A very low risk of disorders of genetic control was observed in assisted-conception children. Overall, there did not appear to be a direct link between assisted reproduction treatment and children's health. The researchers concluded that the cause of some differences in the health of children conceived using assisted reproduction treatment may be due to the age of the woman receiving treatment. Large-scale, research studies are needed to study the long-term health of children conceived using assisted reproduction treatment.
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Affiliation(s)
- B C J M Fauser
- Department of Reproductive Medicine and Gynaecology, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands.
| | - P Devroey
- Center for Reproductive Medicine, Vrije Universiteit Brussel, Laarbeeklaan 101, 1090 Brussels, Belgium
| | - K Diedrich
- Department of Obstetrics and Gynecology, University Clinic of Schleswig-Holstein, Campus Luebeck, 23538 Luebeck, Germany
| | - B Balaban
- Assisted Reproduction Unit, American Hospital of Istanbul, Guzelbahce Sokak No 20, Nisantasi, Istanbul 34365, Turkey
| | - M Bonduelle
- Centre for Medical Genetics, Vrije Universiteit Brussel, Laarbeeklaan 101, 1090 Brussels, Belgium
| | | | - C Estella
- Fundación Instituto Valenciano de Infertilidad (FIVI), Valencia University, and Instituto Universitario IVI/INCLIVA, Parc Científic Universitat de València C/Catedrático Agustín Escardino n(o) 9, Edificio 3, 46980 Paterna, Spain; Departamento de Biología Molecular and Centro de Biología Molecular 'Severo Ochoa' (CSIC-UAM), Universidad Autónoma de Madrid, Madrid, Spain
| | - D Ezcurra
- Global Development and Medical Unit, Merck Serono SA Geneva, Chemin des Mines 9, 1202 Geneva, Switzerland
| | - J P M Geraedts
- Department of Genetics and Cell Biology, Research Institute GROW, Faculty of Health, Medicine and Life Sciences, Maastricht University, Maastricht, The Netherlands
| | - C M Howles
- Global Development and Medical Unit, Merck Serono SA Geneva, Chemin des Mines 9, 1202 Geneva, Switzerland
| | - L Lerner-Geva
- Woman and Child Health Research Unit, Gertner Institute for Epidemiology and Health Policy Research, Tel Hashomer 52621, Israel
| | - J Serna
- Instituto Valenciano de Infertilidad (IVI) Zaragoza, C/María Zambrano, 31, 50018 Zaragoza, Spain
| | - D Wells
- University of Oxford, Nuffield Department of Obstetrics and Gynaecology, Women's Centre, John Radcliffe Hospital, Oxford OX3 9DU, UK
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8
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Teramura T, Sugimoto H, Frampton J, Kida Y, Nakano M, Kawakami M, Izumi H, Fukunaga N, Onodera Y, Takehara T, Fukuda K, Hosoi Y. Generation of embryonic stem cell lines from immature rabbit ovarian follicles. Stem Cells Dev 2013; 22:928-38. [PMID: 23072728 DOI: 10.1089/scd.2012.0300] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
In mammalian ovaries, many immature follicles remain after the dominant follicles undergo ovulation. Here we report the successful production of rabbit embryonic stem cells (ESCs) from oocytes produced by in vitro culture of immature follicles and subsequent in vitro maturation treatment. In total, we obtained 53 blastocysts from oocytes that received intracytoplasmic sperm injection followed by in vitro culture. Although only weak expression of POU5f1 was observed in the inner cell masses of in-vitro-cultured follicle-derived embryos, repeated careful cloning enabled establishment of 3 stable ESC lines. These ESC lines displayed the morphological characteristics of primed pluripotent stem cells. The ESC lines also expressed the pluripotent markers Nanog, POU5f1, and Sox2. Further, these ESCs could be differentiated into each of the 3 different germ layers both in vitro and in vivo. These results demonstrate that immature follicles from rabbits can be used to generate ESCs. Moreover, the use of rabbit oocytes as a cell source provides an experimental system that closely matches human reproductive and stem cell physiology.
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Affiliation(s)
- Takeshi Teramura
- Division of Cell Biology for Regenerative Medicine, Institute of Advanced Clinical Medicine, Kinki University Faculty of Medicine, Osaka, Japan.
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9
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Yamagata Y, Parietti V, Stockholm D, Corre G, Poinsignon C, Touleimat N, Delafoy D, Besse C, Tost J, Galy A, Paldi A. Lentiviral transduction of CD34(+) cells induces genome-wide epigenetic modifications. PLoS One 2012; 7:e48943. [PMID: 23145033 PMCID: PMC3492239 DOI: 10.1371/journal.pone.0048943] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Accepted: 10/02/2012] [Indexed: 02/01/2023] Open
Abstract
Epigenetic modifications may occur during in vitro manipulations of stem cells but these effects have remained unexplored in the context of cell and gene therapy protocols. In an experimental model of ex vivo gene modification for hematopoietic gene therapy, human CD34+ cells were cultured shortly in the presence of cytokines then with a gene transfer lentiviral vector (LV) expected to transduce cells but to have otherwise limited biological effects on the cells. At the end of the culture, the population of cells remained largely similar at the phenotypic level but some epigenetic changes were evident. Exposure of CD34+ cells to cytokines increased nuclear expression of epigenetic regulators SIRT1 or DNMT1 and caused genome-wide DNA methylation changes. Surprisingly, the LV caused additional and distinct effects. Large-scale genomic DNA methylation analysis showed that balanced methylation changes occurred in about 200 genes following culture of CD34+ cells in the presence of cytokines but 900 genes were modified following addition of the LV, predominantly increasing CpG methylation. Epigenetic effects resulting from ex vivo culture and from the use of LV may constitute previously unsuspected sources of biological effects in stem cells and may provide new biomarkers to rationally optimize gene and cell therapy protocols.
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Affiliation(s)
- Yoshiaki Yamagata
- Inserm, U951, Genethon, Evry, France
- Ecole Pratique des Hautes Etudes, UMRS_951, Genethon, Evry, France
- Department of Obstetrics and Gynaecology, Yamaguchi University Graduate School of Medicine, Ube, Japan
| | - Véronique Parietti
- Inserm, U951, Genethon, Evry, France
- Ecole Pratique des Hautes Etudes, UMRS_951, Genethon, Evry, France
| | - Daniel Stockholm
- Inserm, U951, Genethon, Evry, France
- Ecole Pratique des Hautes Etudes, UMRS_951, Genethon, Evry, France
| | - Guillaume Corre
- Inserm, U951, Genethon, Evry, France
- Ecole Pratique des Hautes Etudes, UMRS_951, Genethon, Evry, France
| | - Catherine Poinsignon
- Inserm, U951, Genethon, Evry, France
- Université Evry Val d’Essonne, UMRS_951, Genethon, Evry, France
| | - Nizar Touleimat
- Centre National de Génotypage, CEA – Institut de Génomique, Evry, France
| | - Damien Delafoy
- Centre National de Génotypage, CEA – Institut de Génomique, Evry, France
| | - Céline Besse
- Centre National de Génotypage, CEA – Institut de Génomique, Evry, France
| | - Jörg Tost
- Centre National de Génotypage, CEA – Institut de Génomique, Evry, France
- Fondation Jean Dausset- CEPH, Paris, France
| | - Anne Galy
- Inserm, U951, Genethon, Evry, France
- Ecole Pratique des Hautes Etudes, UMRS_951, Genethon, Evry, France
- Université Evry Val d’Essonne, UMRS_951, Genethon, Evry, France
- * E-mail: (AP); (AG)
| | - András Paldi
- Inserm, U951, Genethon, Evry, France
- Ecole Pratique des Hautes Etudes, UMRS_951, Genethon, Evry, France
- * E-mail: (AP); (AG)
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10
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Harvey AJ, Mao S, Lalancette C, Krawetz SA, Brenner CA. Transcriptional differences between rhesus embryonic stem cells generated from in vitro and in vivo derived embryos. PLoS One 2012; 7:e43239. [PMID: 23028448 PMCID: PMC3445581 DOI: 10.1371/journal.pone.0043239] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2012] [Accepted: 07/18/2012] [Indexed: 01/16/2023] Open
Abstract
Numerous studies have focused on the transcriptional signatures that underlie the maintenance of embryonic stem cell (ESC) pluripotency. However, it remains unclear whether ESC retain transcriptional aberrations seen in in vitro cultured embryos. Here we report the first global transcriptional profile comparison between ESC generated from either in vitro cultured or in vivo derived primate embryos by microarray analysis. Genes involved in pluripotency, oxygen regulation and the cell cycle were downregulated in rhesus ESC generated from in vitro cultured embryos (in vitro ESC). Significantly, several gene differences are similarly downregulated in preimplantation embryos cultured in vitro, which have been associated with long term developmental consequences and disease predisposition. This data indicates that prior to derivation, embryo quality may influence the molecular signature of ESC lines, and may differentially impact the physiology of cells prior to or following differentiation.
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Affiliation(s)
- Alexandra J Harvey
- Department of Physiology, Wayne State University, Detroit, Michigan, United States of America.
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Reis e Silva AR, Bruno C, Fleurot R, Daniel N, Archilla C, Peynot N, Lucci CM, Beaujean N, Duranthon V. Alteration of DNA demethylation dynamics by in vitro culture conditions in rabbit pre-implantation embryos. Epigenetics 2012; 7:440-6. [PMID: 22419129 DOI: 10.4161/epi.19563] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Alterations to DNA methylation have been attributed to in vitro culture and may affect normal embryo development. We chose to analyze DNA methylation reprogramming in the rabbit which, of the species with delayed transcriptional activation of the embryonic genome, allows easy comparisons between in vivo-developed (IVD) and in vitro-cultured (IVC) embryos. In this species, variations in DNA methylation had not previously been quantified, even in IVD embryos. IVD and IVC embryos were recovered at the 2, 4, 8 and 16-cell, morula and blastocyst stages. Immunostaining for 5-methyl-cytidine and normalization of the quantity of methylated DNA vs. the total DNA content were then performed. Our quantitative results evidenced DNA demethylation during pre-implantation development in both IVD and IVC embryos, but with different kinetics. Demethylation occurred earlier in vitro than in vivo between the 2 and 8-cell stages in IVC embryos, reaching its lowest level, while it only started at the 4-cell stage and ended at the 16-cell stage in IVD embryos. We also showed that an absence of serum from the culture medium significantly altered the degree of DNA demethylation. Finally, at the blastocyst stage, ICM was more methylated than the trophectoderm in all cases. Despite a morphological delay observed in in vitro cultured blastocysts, the difference in DNA methylation between ICM and trophectoderm cells appeared at the same time post-fertilization in IVD and IVC embryos, which may reflect another difference in the dynamics of DNA methylation during blastocyst formation. Our data thus clearly establish an effect of embryonic environment on DNA methylation reprogramming during pre-implantation development in a non-rodent species.
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Horii T, Suetake I, Yanagisawa E, Morita S, Kimura M, Nagao Y, Imai H, Tajima S, Hatada I. The Dnmt3b splice variant is specifically expressed in in vitro-manipulated blastocysts and their derivative ES cells. J Reprod Dev 2011; 57:579-85. [PMID: 21666347 DOI: 10.1262/jrd.10-194a] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Manipulation of preimplantation embryos in vitro, such as in vitro fertilization (IVF), in vitro culture (IVC), intracytoplasmic sperm injection (ICSI), somatic cell nuclear transfer (SCNT) and other assisted reproduction technologies (ART), has contributed to the development of infertility treatment and new animal reproduction methods. However, such embryos often exhibit abnormal DNA methylation patterns in imprinted genes and centromeric satellite repeats. These DNA methylation patterns are established and maintained by three DNA methyltransferases: Dnmt1, Dnmt3a and Dnmt3b. Dnmt3b is responsible for the creation of methylation patterns during the early stage of embryogenesis and consists of many alternative splice variants that affect methylation activity; nevertheless, the roles of these variants have not yet been identified. In this study, we found an alternatively spliced variant of Dnmt3b lacking exon 6 (Dnmt3bΔ6) that is specific to mouse IVC embryos. Dnmt3bΔ6 also showed prominent expression in embryonic stem (ES) cells derived from in vitro manipulated embryos. Interestingly, IVC blastocysts were hypomethylated in centromeric satellite repeat regions that could be susceptible to methylation by Dnmt3b. In vitro methylation activity assays showed that Dnmt3bΔ6 had lower activity than normal Dnmt3b. Our findings suggest that Dnmt3bΔ6 could induce a hypomethylation status especially in in vitro manipulated embryos.
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Affiliation(s)
- Takuro Horii
- Laboratory of Genome Science, Biosignal Genome Resource Center, Institute for Molecular and Cellular Regulation, Gunma University, Gunma 371-8512, Japan
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