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Before going into further details about how stem cells are related to human cloning let’s see what cloning actually is.
Cloning is the creation of multiple copies of a single molecule, cell, or virus. Depending upon the actual process there
are many different kinds of cloning, most of which are now commonplace in science. Cloning has allowed scientists to develop
powerful new drugs and to produce insulin and useful bacteria in the lab. It also allows researchers to track the origins of
biological weapons, catch criminals and free innocent people, and produce new plants and livestock to feed an undernourished
world population .
Stem cells are basically primitive cells, found both in embryos and in adults that can morph into various
specialized types of tissue, such as brain cells or heart cells. The term "therapeutic cloning" is sometimes used
to refer to the creation by cloning of human embryos for research, including (but not limited to) the harvesting of
their stem cells. The term "reproductive cloning" is sometimes used to mean implanting such an embryo in a womb and
bringing them to birth. We must distinguish between repugnant reproductive cloning and potentially life-saving therapeutic cloning.
Adult tissues also contain stem cells, unlike that of the embryonic stem cells and embryonic germ cells these are
generally multipotent and only develop into cells of a specific tissue or organ type. These cells are in many types
of adult tissues to replenish cells that wear out. Not all tissue types have been found to contain multipotent stem
cells, but more and more discoveries are being made by almost every passing day in the medical field. Until recently
it was thought that our nervous systems had no stem cells, that we were born with a certain amount of brain cells and
then they just kept dying the older we got. But due to latest advancements and research initiatives it has been made
clear that this is not the case.
We are finding out by different cell differentiation techniques that some specified and even determined cells may be
able to undergo a process called trans-differentiation where they can respecify into different cell types. So then,
why do we not simply use adult stem cells? Well, simply put, this trans-differentiation is not a natural process and
may lead to adverse effects if respecified cells were transplanted. Until scientists are positive trans-differentiated
adult stem cells would act normally and there is a quick and effective way of locating, removing and growing enough of
our own cells we will have to continue to look at different sources. One positive aspect of using our own cells is a lack of
immune response that would occur if another person's cells were used (the brain is an exception and will not fire an immune response).
Another way to use our DNA and therefore not has an immune response to transplant is called somatic cell nuclear
transfer (SCNT). SCNT is a process that forms an embryo by implanting the nucleus of a body cell into an enucleateed
oocyte-- an egg cell that has had its own genome removed. Stem cells can be harvested from the resultant embryo, but
this process is highly controversial as well. The embryo could be developed into a human being, and that would make
SCNT the along the same grounds as cloning. Human reproductive cloning is illegal in the US and similarly regarded as
unacceptable in most other countries. There is some debate on whether the use of SCNT to produce stem cells for
treatment, a process known as therapeutic cloning, would be admissible as the technology progresses .
Somatic Cell Nuclear Transfer (SCNT) or therapeutic cloning involves removing the nucleus of an unfertilized
egg cell, replacing it with the material from the nucleus of a "somatic cell" (a skin, heart, or nerve cell, for example),
and stimulating this cell to begin dividing. Once the cell begins dividing, stem cells can be extracted 5-6 days later and
used for research. The AAMC supports on-going research into SCNT and has endorsed legislation that would allow such research to flourish.
Reproductive cloning, on the other hand, is intended to create human beings by cloning human embryos. The Association
of American Medical Colleges (AAMC) and the National Academy of Sciences recommends a legally enforceable ban on all
forms of this type of cloning. According to AAMC to expose any person to the known risks and uncertainties involved in
reproductive cloning would be unethical and unconscionable.
However, the difference between reproductive cloning and the use of cloning technology that does not create a human
being should be clearly recognized. According to the recent report of the National Academies of Science that states,
"The scientific and medical considerations that justify a ban on human reproductive cloning at this time are not
applicable to nuclear transplantation to produce stem cells." This technology has potentially important applications
in research, medicine and industry, including genetically engineered human cell cultures that would serve as
"therapeutic tissues" in the treatment of currently intractable human diseases.
Actually, these uses of cloning technology are not intended to lead to a cloned human being, nor do they. The
AAMC urges Congress to oppose legislation that would prohibit research on the use of nuclear transplantation to
produce stem cells. Such a blanket prohibition would have grave implications for future advances in medical research
and human healing. Since other nations have already decided not to enact such law, a Congressional ban would also pose
a serious threat to the continued world leadership of the United States in medical research and biotechnology.
According to the National Institutes of Health, nuclear transplantation could provide an invaluable approach to
studying how cells become specialized, which in turn could provide new understanding of the mechanisms that lead
to the development of the abnormal cells responsible for cancers and certain birth defects. Improved understanding
of cell specialization may also provide answers to how cells are regulated and how they age- leading to new insights
into the treatment or cure of Alzheimer's and Parkinson's diseases, or other incapacitating degenerative disease of
the brain and spinal cord.
The technology promises also to help us understand how to activate certain genes to permit the creation of
customized cells for transplantation or grafting. Such cells would be genetically identical to the cells of the
donor and could therefore be transplanted into that donor without fear of immune rejection, the major biological
barrier to organ and tissue transplantation at this time.
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