Scientific and Medical Aspects of Human Reproductive Cloning (2002) / Chapter Skim
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2. Cloning: Definitions and Applications
2. Cloning: Definitions and Applications
Pages 24-38
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From page 24... ...
-1~ - - r WHAT IS MEANT BY REPRODUCTIVE CLONING OF ANIMALS INCLUDING HUMANS? Reproductive cloning is defined as the deliberate production of genetically identical individuals.
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From page 25... ...
Techniques not yet developed or described here would nonetheless constitute cloning if they resulted in genetically identical individuals of which at least one were an embryo destined for implantation and birth. The two methods used for reproductive cloning thus far are as follows: · Cloning using somatic cell nuclear transfer (SCNT)
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From page 26... ...
A pair of clones will experience different environments and nutritional inputs while in the uterus, and they would be expected to be subject to different inputs from their parents, society, and life experience as they grow up. If clones derived from identical nuclear donors and identical mitocondrial donors are born at different times, as is the case when an adult is the donor of the somatic cell nucleus, the environmental and nutritional differences would be expected to be more pronounced than for monozygotic (identical)
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From page 27... ...
HOW DOES REPRODUCTIVE CLONING DIFFER FROM STEM CELL RESEARCH? The recent and current work on stem cells that is briefly summarized below and discussed more fully in a recent report from the National Academies entitled Stem Cells and the Future of Regenerative Medicine [11]
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From page 28... ...
Stem cells are rarer [24] and more difficult to find in adults than in preimplantation embryos, and it has proved harder to grow some kinds of adult stem cells into cell lines after isolation [25; 26~.
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From page 29... ...
Moreover, in the case of a disorder that has a genetic origin, a patient's own adult stem cells would carry the same defect and would have to be grown and genetically modified before they could be used for therapeutic transplantation. The application of somatic cell nuclear transfer or nuclear transplantation offers an alternative route to obtaining stem cells that could be used for transplantation therapies with a minimal risk of transplant rejection.
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From page 30... ...
That might be reasonably straightforward for a simple structure, such as a pancreatic islet that produces insulin, but it is more challenging for tissues as complex as that from lung, kidney, or liver [54; 55~. The experimental procedures required to produce stem cells through nuclear transplantation would consist of the transfer of a somatic cell nucleus from a patient into an enucleated egg, the in vitro culture of the embryo to the blastocyst stage, and the derivation of a pluripotent ES cell line from the inner cell mass of this blastocyst.
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From page 31... ...
The preparation of embryonic stem cells by nuclear transplantation differs from reproductive cloning in that nothing is implanted in a uterus. The issue of whether ES cells alone can give rise to a complete embryo can easily be misinterpreted.
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From page 32... ...
If the differentiation of ES cells into specialized cell types can be understood and controlled, the use of nuclear transplantation to obtain genetically defined human ES cell lines would allow the generation of genetically diverse cell lines that are not readily obtainable from embryos that have been frozen or that are in excess of clinical need in IVF clinics. The latter do not reflect the diversity of the general population and are skewed toward genomes from couples in which the female is older than the period of maximal fertility or one partner is infertile.
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From page 33... ...
Embryonic stem cells derived through nuclear transplantation into eggs are a potential source of pluripotent (embryonic) stem cell lines that are immunologically similar to a patient's cells.
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From page 34... ...
SHAPIRO SS, WAKNITZ MA, SWIERGIEL JJ, MARSHALL VS, JONES JM. Embryonic stem cell lines derived from human blastocysts.
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From page 35... ...
TABAR V, RODRIGUEZ I, PERRY AC, STUDER L, MOMBAERTS P Differentiation of embryonic stem cell lines generated from adult somatic cells by nuclear transfer.
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ODORICO JS, KAUFMAN DS, THOMSON JA. Multilineage differentiation from human embryonic stem cell lines.
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From page 37... ...
WAGNER EF. Generation of completely embryonic stem cell-derived mutant mice using tetraploid blastocyst injection.
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From page 38... ...
ITSKOVITZ-ELDOR, J., SCHULDINER, M., KARSENTI, D., EDEN, A., YANUKA, O., AMIT, M., SOREQ, H., AND BENVENISTY, N Differentiation of human embryonic stem cells into embryoid bodies compromising the three embryonic germ layers.
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