Embryonic cell nuclear transfer

Human embryonic stem cells (hESCs) were first derived from the inner cell mass (ICM) from the blastocyst stage (-100-200 cells) of embryos generated by in vitro fertilization [35,36]. In humans the blastocyst is an early-stage embryo, approximately 4 to 5 days old. The blastocyst can be formed by means of either in vitro fertilization or somatic cell nuclear transfer, in which the nucleus of a somatic cell is combined with an enucleated oocyte. Methods have been developed to derive hESCs from the late morula stage (30-40 cells) and from arrested embryos (16-24 cells incapable of further development), and more recently from single blastomeres isolated from 8-cell embryos (37). 

One approach to overcome the transplant rejection of human embryonic stem (ES) cells is to derive them by nuclear transfer of the patients own cells. In the absence of an efficient protocol for human somatic cell nuclear transfer (SCNT), several critical steps must be optimized, namely reprogramming time, activation method, and in vitro culture conditions. Reprogramming time was defined as the time between cell fusion and oocyte activation to permit proper embryonic development. A 2 h reprogramming time led to 25% of the recon-stracted embryos developing to blastocysts. In SCNT, in the absence of sperm-mediated activation, an artificial stimulus is needed to initiate embryo development. Addition of 10 pM ionophore for 5 min, and incubation with 2.0 mM 6-dimethyl aminopurine for 4 h, was the most efficient chemical activation protocol for human SCNT embryos. Encouragingly, inefficiencies in embryo culture have been overcome by supplementing... 

Bovine embryonic renal Nuclear transfer artificial Cell organization Neo-kidneys ESRD 71 g... 

Another quantum leap for modern biotechnology was the first cloned mammal by Ian Willmut in 1996 (see his quote for Modern Biopharmaceuticals ) by means of somatic cell nuclear transfer (SCNT) -the sheep Dolly . Then, in 2004, the first human embryo was cloned by a team led by Woo Suk Hwang, who was able to obtain pluripotent embryonic stem cells by SCNT of reprogrammed human adult cells. The highly differentiated genetic pro-... 

Lu S, Wang H et al (2010) Both the transplantation of somatic cell nuclear transfer- and fertilization-derived mouse embryonic stem cells with temperature-responsive chitosan hydrogel improve myocardial performance in infarcted rat hearts. Tissue Eng A 16 1303-15... 

Byrne JA, Pedersen DA, Clepper LL, Nelson M, Sanger WG, Gokhale S, Wolf DP, Mitalipov SM. 2007. Producing primate embryonic stem cells by somatic cell nuclear transfer. Nature 450 497-502. 

Stice, S.L., Strelchenko, N.S., Keefer, C.L., and Mathews, L. (1996). Plmipotent bovine embryonic cell lines direct embryonic development following (nuclear transfer. Biol. Reprod. 54,100-110. 

Korean scientists improve success rate of human adult nuclear transfer to embryonic cells by 10 fold... 

Wakayama, T., V. Tabar, I. Rodriguez, A.C. Perry, L. Studer, and P. Mombaerts, Differentiation of embryonic stem cell lines generated from adult somatic cells by nuclear transfer. Science, 2001. 292(5517) 740-3. 

Wakayama, T. (2006). Establishment of nuclear transfer embryonic stem cell lines from adult somatic cells by nuclear transfer and its application. Ernst Sobering Res Found Workshop, 60, 111-23. 

Hurlbut, W.B. (2005). Altered nuclear transfer as a morally acceptable means for the procurement of human embryonic stem cells. Perspect Biol Med, 48, 211-28. 

Wakayama, S., Jakt, M.L., Suzuki, M., Araki, R., Hikichi, T., Kishigami, S., Ohta, H., Van Thuan, N., Mizutani, E., Sakaide, Y., Senda, S., Tanaka, S., Okada, M., Miyake, M., Abe, M., Nishikawa, S., Shiota, K., Wakayama, T. (2006). Equivalency of nuclear transfer-derived embryonic stem cells to those derived from fertilized mouse blastocysts. Stem Cells, 24,2023-33. 

As late as 1984, scientists David McGrath and Davor Solter wrote in the journal Science, The cloning of mammals by simple nuclear transfer is biologically impossible. That assertion has been proven false, and since that date sheep, mice, cows, monkeys—a virtual menagerie of mammals—have been cloned. A moratorium on the cloning of humans has been enforced by law and by intimidation. Yet the announcement of the first true human clone— from somatic cell and egg cell fusion to embryonic birth—is only a question of time. Whether it occurs in a federal laboratory or in a private clinic, it will happen. 

Lanza et al. [71] investigated the use of nuclear transfer to generate functional renal structures. Renal cells obtained from an early-stage cloned bovine fetus (embryonic day 56, cloned from adult bovine fibroblasts) were used to generate functional immune-compatible renal tissues. The cloned renal cells were expanded in vitro, seeded onto collagen-coated cylindrical polycarbonate membranes to form renal devices, and implanted back into the nuclear donor animal without immune destruction. The embryonic precursor cells organized themselves into glomeruli- and tubule-like structures with the ability to... 

HATTORi M, HASHiMOTO H, BUBENSHCHiKOVA E and WAKAMATSu Y (2011) Nuclear transfer of embryonic cell nuclei to non-enucleated eggs in zebrafish, Danio rerio. Int... 

Kim, K., Ng, K., Rugg-Gunn, P. J. et al. 2007. Recombination signatures distinguish embryonic stem cells derived by parthenogenesis and somatic ceU nuclear transfer. Cell Stem Cell 1 346-52. 

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