Cloning embryonic cells

Cloning. Asexual propagation (cloning) of plants ordinarily occurs by virture of the ability of embryonic meristematic tissue to differentiate into roots and shoots. If isolated phloem cells or other more differentiated cells are cultured, the result is often the formation of a callus, a dedifferentiated mass of cells somewhat reminiscent of embryonic cells. Under proper conditions, e.g., in a coconut milk culture and in the presence of the correct auxin-to-cytokinin ratio, some carrot root phloem cells revert to embyronic cells and develop into intact plants.99 This experiment provided proof that the differentiated carrot phloem cells... 

Davids, B.J., Wu, X.J. and Yoshino, T.P. (1 999) Cloning of a beta integrin subunit cDNA from an embryonic cell line derived from the freshwater mollusc, Biomphalaria glabrata. Gene 228, 213-223. 

Tumour cells are allowed to attach to gelatin-coated tissue culture dishes (see 2.4.1) when many different kinds of cells including embryonal cells grow out. These latter cells may eventually outgrow the differentiated cells and they may then be cloned (Chapter 7) (Rosenthal et al., 1970 Bernstine et al., 1973). Lines isolated in this way tend after some time to lose their ability to differentiate. 

Hai DC. 2007. Direct differentiation of human embryonic stem cells to hepatocyte-like cells exhibiting functional activities. Cloning Stem Cells 9, 51-62. 

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... 

So far, animal clones developed from somatic cells have shown several weaknesses that clones from separated embryonic cells have not shown. One of these is premature aging, possibly caused by the shortened telomeres on the ends of the DNA strands taken from the original somatic cells. There have been other physical weaknesses noted, as well. Thus, animal cloning is still in its infancy. 

Any gardener who has used a cutting from one plant to grow an identical plant has created a clone of the original plant, since clones are organisms that contain identical DNA. Based on that definition, identical twins are essentially clones of each other. The first successful laboratory cloning of an animal involved a tadpole, and occurred in 1952. It took more than 40 years of research before a mammal, Dolly the sheep, was cloned from an adult cell rather than an embryonic cell. Since that success in 1996, numerous other successful mammalian clonings have been achieved in the laboratory. 

Therapeutic cloning uses the same procedures as reproductive cloning however, instead of transferring the cloned embryo into the womb of a surrogate mother, the embryo is further manipulated in the laboratory to make cell cultures of embryonic cells for basic or clinical research. 

Therapeutic Cloning. To make embryonic cell cultures, cloned embryos are made by means of somatic cell nuclear transplantation. They are then either disassembled in the laboratory and used to establish embryonic cell cultures or gestated in a surrogate... 

Klimanskaya, I., Hipp, J., Rezai, K. A., West, M., Atala, A., and Lanza, R. 2004. Derivation and comparative assessment of retinal pigment epithehum from human embryonic stem cells using transcriptomics. Cloning Stem Cells, 6 217-45. 

Lund, R. D., Wang, S., Klimanskaya, I., Holmes, T, Ramos-Kelsey, R., Lu, B., Girman, S., Bischoff, N., Sauve, Y, and Lanza, R. 2006. Human embryonic stem cell-derived cells rescue visual function in dystrophic RCS rats. Cloning Stem Cells, 8 189-99. 

Rishi AK, Joyce-Brady M, Fisher J, Dobbs LG, Floras J, VanderSpek J, Brody JS, Williams MC (1995) Cloning, characterization, and development expression of a rat lung alveolar type I cell gene in embryonic endodermal and neural derivatives. Dev Biol 167(1) 294-306... 

We can divide cloning into therapeutic cloning and reproductive cloning. Therapeutic cloning is synonymous with stem cell research. Under proper control and environment, embryonic stem cells can potentially be directed to grow and develop into different tissues that are invaluable for replacing... 

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