Nuclear transplantation in sheep embryos

Willadsen, S. M.

doi:10.1038/320063a0

Cited by 691 publications

(277 citation statements)

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“…Furthermore, blastocysts and outgrowths with low or absent Oct4-GFP did not give rise to ES cells. Somatic and embryonic cell cloning experiments have shown that, compared with the metaphase II ooplasm, the zygotic cytoplasm is an inadequate host to the transplanted nucleus (McGrath and Solter 1984;Robl et al 1986;Willadsen 1986;Howlett et al 1987;Cheong et al 1993Cheong et al , 1994. It is generally assumed that reprogramming subsequent to activation is minor; therefore, much effort to improve clone development has focused on the metaphase II ooplasm (Sun and Moor 1995;DiBerardino 1997;for review, see Solter 2000).…”

Section: Discussionmentioning

confidence: 99%

Oct4 distribution and level in mouse clones: consequences for pluripotency

Boiani¹,

Eckardt²,

Schöler³

et al. 2002

Genes Dev.

482

332

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Somatic cell clones often fail at a developmental stage coincident with commencement of differentiation. The transcription factor Oct4 is expressed during cleavage stages and is essential for the differentiation of the blastocyst. Oct4 expression becomes restricted to the inner cell mass and epiblast. After gastrulation Oct4 is active only in germ cells and is silent in somatic cells. Here, Oct4 and an Oct4-GFP transgene were used as markers for which gene reprogramming could be directly related to the developmental potential of somatic cell clones. Cumulus cell clones initiated Oct4 expression at the correct stage but showed an incorrect spatial expression in the majority of blastocysts. The ability of clones to form outgrowths was reduced, and the outgrowths had low or even undetectable levels of Oct4 RNA or GFP. The quality of GFP signals in blastocysts correlated with the ability to generate outgrowths that maintain GFP expression and the frequency of embryonic stem (ES) cell derivation. Abnormal Oct4 expression in clones is either directly or indirectly caused by reprogramming errors and is indicative of a general failure to reset the genetic program. The abnormal Oct4 expression may be associated with aberrant expression of other crucial developmental genes, leading to abnormalities at various embryonic stages. Regardless of other genes, the variations observed in Oct4 levels alone account for the majority of failures currently observed for somatic cell cloning.

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Section: Discussionmentioning

confidence: 99%

Oct4 distribution and level in mouse clones: consequences for pluripotency

Boiani¹,

Eckardt²,

Schöler³

et al. 2002

Genes Dev.

482

332

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“…All clones were derived by nuclear transplantation using nuclei from blastomeres as donors (Willadsen, 1986;Prather et al, 1987Prather et al, , 1989. Importantly, these researchers used oocytes rather than zygotes as recipients.…”

Section: Mammalian Nuclear Transfer: Selected Highlightsmentioning

confidence: 99%

“…For normal development to proceed, it is crucial that, in a Briggs et al, 1952Briggs et al, 1962 Nuclear transfer-derived frogs Gurdon, 1962Gurdon, 1975 Rabbit nuclear transfer Bromhall, 1975Bromhall, 1979 Nuclear transplantation in fish Gasaryan et al, 1979Gasaryan et al, 1981 Derivation of mouse ES cells Evans and Kaufman, 1981;Martin, 1981Martin, 1983 Nuclear transplantation in the mouse Solter, 1983 1986 Lambs cloned from blastomeres Willadsen, 1986Willadsen, 1987 Cattle cloned from blastomeres Prather et al, 1987Prather et al, 1989 Pigs cloned from blastomeres Prather et al, 1989Prather et al, 1994 Calves cloned from ICM cells First, 1994 1996 Sheep cloned from embryonic cell line Campbell et al, 1996 First mammal cloned from adult cell (sheep "Dolly") Wilmut et al, 1997Wilmut et al, 1998 Derivation of human ES cells Thomson et al, 1998Thomson et al, 2000 Mouse nuclear transfer-derived ES cells Munsie et al, 2000Munsie et al, 2002 Terminally differentiated cells cloned Hochedlinger et al, 2002aHochedlinger et al, 2002 First therapeutic application in mice Rideout et al, 2002 a ES, embryonic stem; ICM, inner cell mass. This table summarizes a number of selected highlights starting from the first demonstration of the NT technique by Briggs and King to the first "proof of principle" study in mice showing the therapeutic potential of the technique.…”

Section: Nt Efficiencymentioning

confidence: 99%

Mammalian nuclear transfer

Meissner

Jaenisch

2006

Developmental Dynamics

112

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During development, the genetic content of each cell remains, with a few exceptions, identical to that of the zygote. Differentiated cells, therefore, retain all the genetic information necessary to generate an entire organism (nuclear totipotency). Nuclear transfer (NT) was initially developed to test experimentally this concept by cloning animals from differentiated cells. It has, since then, been used to study the role of genetic and epigenetic alterations during development and disease. In this review, we highlight some of the milestones in mammalian NT reached in the 50 years after the first nuclear transplantations in frogs. We also address problems associated with mammalian nuclear transfer and provide a survey on current NT and stem cell technology. In the long term, nuclear transfer or alternative strategies aim to generate customized pluripotent cells, which would be invaluable to medical research and therapy. Developmental Dynamics 235: 2460 -2469, 2006.

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“…The first scientist who successfully used cytoplasts produced by enucleation of metaphase II oocytes was Steen Willadsen [12]. In his experiments, blastomeres isolated from 8-cell stage embryos were fused to mature oocyte cytoplasts and several lambs were born.…”

Section: Birth Of Dollymentioning

confidence: 99%

The ups and downs of somatic cell nucleus transfer (SCNT) in humans

Fulka

Langerova

Loi

et al. 2013

J Assist Reprod Genet

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Achieving successful somatic cell nuclear transfer (SCNT) in the human and subhuman primate relative to other mammals has been questioned for a variety of technical and logistical issues. Here we summarize the gradual evolution of SCNT technology from the perspective of oocyte quality and cell cycle status that has recently led to the demonstration of feasibility in the human for deriving chromosomally normal stem cells lines. With these advances in hand, prospects for therapeutic cloning must be entertained in a conscientious, rigorous, and timely fashion before broad spectrum clinical applications are undertaken.Keywords Nucleus . Oocyte . Nucleus transfer Simply stated, SCNT in mammals should in practice be a very straightforward technique. First, cytoplasts are prepared by enucleating the metaphase II stage oocytes, i.e. metaphase II chromosomes are removed from the oocyte. Second, the selected nucleus is introduced into the cytoplast either by direct injection or by induced cell fusion. The reconstructed SCNT products are then activated in ways mimicking fertilization and if everything goes well cloned embryos develop [6].Logically, since following the birth of Dolly [7], and the production of additional clones in other mammalian species, there is ample confirmation that Dolly was not an exceptional case, prompting widespread discussion regarding the pros and cons of human SCNT. Given this prospect, it has been commonly accepted and broadly emphasized that the production of cloned human individuals must be banned (reproductive cloning). On the other hand, the production of embryos from which patient compatible embryonic stem cells could be obtained seemed to be acceptable, at least in some countries (therapeutic cloning). However, once the discovery of induced pluripotent stem cell production (iPSC) was realized by the work of Takahashi and Yamanaka [see 8 for review], illustrating that differentiated or even terminally differentiated cells can be converted (dedifferentiated) into a pluripotent state by induced overexpression of four factors (Oct 4, Sox 2, Klf 4, c-Myc; OSKM), greater resistance against the use of SCNT in humans has emerged, including the prospect of therapeutic cloning.Although many papers on modifications of the original iPS technology seeking improved efficiency and safety have been published, it should be emphasized that our understanding of the mechanisms by which iPSC elicits dedifferentiation remain woefully incomplete. Instead, it is commonly accepted that the oocyte cytoplasmic milieu is the most direct means to obtaining reprogramming of a differentiated somatic cell nucleus [9,10]. This fact-the quality of the oocyte cytoplasmic milieu-may well underscore the reason that while research on human SCNT continues, reports are rare in this species relative to the many papers published in other mammals. Birth of DollyThe work that led to the birth of Dolly was antedated by many years of experiments using laboratory and domestic animals to test many methodological combinations ...

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Nuclear transplantation in sheep embryos

Cited by 691 publications

References 10 publications

Oct4 distribution and level in mouse clones: consequences for pluripotency

Oct4 distribution and level in mouse clones: consequences for pluripotency

Mammalian nuclear transfer

The ups and downs of somatic cell nucleus transfer (SCNT) in humans

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