Stem Cell Research. An embryonic stem (ES) cell is any cell taken from a pre-implantation embryo. ES cells are totipotent, that is, they retain the potential to form any specialized cell type in the body. Totipotency is a characteristic of cells in the inner cell mass of a pre-implantation blastocyst. A non-embryonic stem cell, on the other hand, is a cell from a slightly later stage of fetal development that can proliferate in an undifferentiated state, as well as give rise to differentiated cell lines. These latter stem cells are merely pluripotent, that is, relatively unspecialized stem cells not yet committed to becoming specific types of derived cells; for example, a dermal stem cell that can give rise to the several types of dermal tissues, but cannot give rise to brain tissue. Both types of stem cells can be manipulated in gene targeting and whole organism cloning.
Cloning. Whole organism cloning depends upon the manipulation of totipotent embryonic stem cells, or—as in the well-known case of Dolly the sheep—the technical reversion of a pluripotent stem cell into one that is thought to be totipotent. Advocates of cloning argue that unrestricted stem cell research is a critical prerequisite to realize any of the potential benefits of whole organism cloning.
Whole organism cloning is the creation of a collection of genetically identical individuals that have been derived from a single parent cell; that is, the clone has been reproduced asexually. In biotechnology, cloning usually involves growing genetically identical vectors or host cells—usually bacteria, yeast, or non-human mammalian cells grown in culture—which all contain the same piece of inserted recombinant DNA, including the target gene.9
One of the aims of stem cell research and whole organism cloning is the husbandry of pharmaceutically valued DNA fragments that have been successfully recombined into a larger organism. These fragments can then be harvested at will from that organism or from other clones of that organism. Recombinant human insulin, for example, is currently harvested from clones of bacteria that multiply rapidly in industrial-sized fermenting vats. The clones yield pounds of less toxic and less expensive product. Biotechnologists argue that the insertion of the same human insulin gene into a mammal instead of a bacterium so that product can be harvested daily from normal transgenic mammalian milk, is a logical quantitative but not qualitative next step in this process. The proximate benefit of this process, it is argued, is a safer medical product (insulin, in this case) that can be substituted by injection for a patient's defective gene product, and that humanely saves the lives of juveniles afflicted with insulin-dependent diabetes mellitus (IdDM).
Knowledge of these processes is not yet widespread, and one of the medical specialties that seeks to inform the public about these issues is genetic counseling.
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