Sheep cloned by nuclear transfer from a cultured cell line

Abstract

Nuclear transfer has been used in mammals as both a valuable tool in embryological studies and as a method for the multiplication of 'elite' embryos. Offspring have only been reported when early embryos, or embryo-derived cells during primary culture, were used as nuclear donors. Here we provide the first report, to our knowledge, of live mammalian offspring following nuclear transfer from an established cell line. Lambs were born after cells derived from sheep embryos, which had been cultured for 6 to 13 passages, were induced to quiesce by serum starvation before transfer of their nuclei into enucleated oocytes. Induction of quiescence in the donor cells may modify the donor chromatin structure to help nuclear reprogramming and allow development. This approach will provide the same powerful opportunities for analysis and modification of gene function in livestock species that are available in the mouse through the use of embryonic stem cells.

Mechanisms of nuclear reprogramming by eggs and oocytes: a deterministic process?

“…The remarkable stability of cell differentiation under normal conditions can be reversed experimentally by nuclear transfer, cell fusion and induced pluripotent stem (iPS) cell technology [1][2][3][4][5] . This provides an opportunity to generate pluripotent embryonic cells from adult cells of the same individual and hence opens the possibilit y of cell replacement without the need for immunosuppression.…”

“…The egg and oocyte reprogramming process includes the exchange of somatic proteins for oocyte proteins, the post-translational modification of histones and the demethylation of DNA. These events occur in an ordered manner and on a defined timescale, indicating that reprogramming by nuclear transfer and by cell fusion rely on deterministic processes.The remarkable stability of cell differentiation under normal conditions can be reversed experimentally by nuclear transfer, cell fusion and induced pluripotent stem (iPS) cell technology [1][2][3][4][5] . This provides an opportunity to generate pluripotent embryonic cells from adult cells of the same individual and hence opens the possibilit y of cell replacement without the need for immunosuppression.…”

Updates on stem cells and their applications in regenerative medicine

“…Nuclear cloning (also known as nuclear transfer) involves the introduction of a nucleus from a donor cell into an enucleated oocyte to generate an embryo with a genetic make-up that is 99.5% identical to that of the donor.from nuclear transfer was reported in Gurdon (1962) at the University of Oxford. Later came the cloning of Dolly the sheep in Edinburgh in 1996, which was remarkable, since she was the first mammal derived from an adult somatic cell (Campbell et al, 1996). Two types of nuclear cloning were described: (a) reproductive cloning, leading to generation of an embryo for continuation of life; and (b) therapeutic cloning, generating early stage embryos for ESCs procurement, used in research and cellbased therapies.…”

Xenopus, the next generation: X. Tropicalis genetics and genomics

“…Haploid cell lines have been created from amphibians (where one can use UV-inactivated sperm to readily create haploid embryos, as noted earlier) for early studies on somatic cell genetics (Freed and Mezger-Freed, 1970). Although classic nuclear transplantation techniques result in few normal embryos, the more recent modifications of these methods (e.g., using cells in the G o phase of the cell cycle; Campbell et al, 1996) have not been reported in amphibians.…”