THERAPEUTIC
CLONING,
TO
CREATE HUMAN ORGANS
What is Cloning?
Cloning is the production of one or more individual
plants or animals (whole or in part) that are genetically identical to an
original plant or animal.
Three very different procedures
have been referred to as "cloning." Two are:
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Adult DNA
cloning (a.k.a. cell nuclear
replacement): This involves removing the DNA from an embryo and replacing it
with the DNA from a cell removed from an individual. Then, the embryo would
be implanted in a woman's womb and be allowed to develop in to a new human
whose DNA is identical to that of the original individual. This method has
been used to clone a sheep. The initial steps of the procedure were tried
using human DNA in 1998-DEC. Adult DNA cloning cannot ethically be used
to produce a human clone, because experiments on animals have sometimes
produced defective specimens. |
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Therapeutic
cloning: This starts with
the same procedure as is used in adult DNA cloning. The resultant embryo
would be allowed to grow for perhaps 14 days. It's stem cells would then be
extracted and encouraged to grow into a piece of human tissue or a complete
human organ for transplant. The end result would not be a human being; it
would be a replacement organ, or piece of nerve tissue, or quantity of skin.
The first successful therapeutic cloning was accomplished in 2001-NOV by
Advanced Cell Technology, a biotech company in Worcester, MA. |
What
is therapeutic cloning?
Therapeutic cloning would involve
growing replacement organs (heart, liver, pancreas, skin, etc) from a sample of
a person's DNA. The procedure would likely involve the use of a human embryo
that has been modified by cell nuclear replacement, and the extraction of the
embryo's stem cells. Therapeutic cloning has not yet been accomplished in the
laboratory or clinic. However, a general approach by which it might be done in
the future has been mapped out. It would probably involve a multi-step process:
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A DNA sample
would be taken from a sick patient. |
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The sample would
be inserted into an embryo in place of its original DNA. |
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The embryo would
be allowed to grow for perhaps two weeks. |
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Stem cells would be
removed from the embryo. This is a destructive step; the embryo would be
killed in the process. |
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The stem cells
would be encouraged to grow into whatever tissue or organ is needed to treat
the patient. Stem
cells are a unique form of human cell that can theoretically develop into
many organs or body parts the body. |
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The tissue or
organ would be transplanted into the patient. 4 |
Future experiments
may not succeed. There were four main hurdles to overcome:
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Stem cells have
to be "successfully isolated and grown in the laboratory."
This has already been accomplished |
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They have to be
encouraged to "turn into specific cell types." This has been
done for most of the 220 cell types in the human body. |
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They have to be
proven usable in treating patients with diseases, injuries, or disorders. |
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The transplanted
tissue must develop normally and must not represent significant "risks
to the patient." 4 |
If scientists are
successful, it would probably take many years of research before the first
useful results will be obtained.
What
are its possible benefits?
If therapeutic cloning using
embryos is successful, then perfectly matched, replacement organs could become
freely available to sick and dying people. That would save countless numbers of
lives, and increase the quality of life of countless others. Three possible
examples of therapeutic cloning "might include the use of insulin-secreting
cells for diabetes; nerve cells in stroke or Parkinson’s disease; or liver
cells to repair a damaged organ." 4 There would
probably also be side benefits resulting from the research. "Further
advances in understanding of how organs regenerate would increase the range of
possible treatments that could be considered." 4
In the United States during 1998,
"More than 50 disease advocates and scientific societies, representing
such concerns as diabetes, blindness, Parkinson's disease, glaucoma, AIDS, Down
Syndrome, cystic fibrosis, stroke, lymphoma, infertility and cancer--as well as
professional groups that focus on such issues as cell biology, aging,
microbiology, ophthalmology, cardiology, pediatrics and reproductive
medicine--recently sent a letter to members of Congress urging them to support
federal funding for...[stem cell] research." 1
This procedure would have a number
of advantages, when compared to regular organ transplant donated by a second
person:
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There would be
presumably be no danger of rejection of the transplant because the organ's
DNA would match the patient's DNA exactly. |
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For transplants
involving kidney (or theoretically any other organ that is duplicated in the
body), another individual would not have to experience pain, inconvenience,
and potentially shortened life span in order to donate the organ. |
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The patient would
not have to wait until an unrelated donor dies to obtain a transplant. A new
organ could be grown for them as needed. |
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The patient would
not have to make-do with a replacement organ that is old and may have reduced
functionality; a brand-new organ would be grown specifically for them. |
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The procedure
would save lives which would otherwise be lost waiting for a transplant that
did not come in time. |
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The potential
exists to cure, or at least treat, certain diseases and disorders that cannot
be effectively handled today. |
Ethical
considerations:
Ethics become a concern because of
the source of the stem cells.
Stem cells could be obtained from
other sources:
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Embryos created
during infertility treatment. These are sometimes called "spare
embryos." They are usually frozen at a very low temperature in the
event that they are needed in the future to attempt another a pregnancy. |
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Embryos created
for the purpose in the laboratory by manually fertilizing an ovum with
donated sperm. |
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From the germ
cells or organs of an aborted fetus. These "appear to be limited in
the type of tissue they can be developed into." |
Unfortunately, organs
grown from stem cells from one of these sources would have foreign DNA that did
not match the DNA of the organ recipient. The recipient would have to take
anti-rejection drugs for the rest of their life and could suffer organ
rejection at any time.
There are four other sources that
would produce organs that are perfectly matched to the recipient's DNA. They
would presumably prevent organ rejection:
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Via cell nuclear
replacement, as described above. The nucleus in an ovum is removed and
replaced by the nucleus from an adult cell from the patient. |
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From bone marrow
and some other adult tissues. These are expected to have limited usefulness. |
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From "mature
adult tissue cells reprogrammed to behave like stem cells." This
mechanism is purely speculative at this time. |
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From umbilical
cord blood collected at the person's birth. This would require cord blood to
be collected when a person is born and stored for possible future use. These
stem cells also appear to have limited flexibility and usefulness. |
Embryos appear to be
the only source of stem cells that would have wide potential in therapeutic
cloning. No societal consensus exists about the ethics of destroying a human
embryo in order to collect stem cells.
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Many conservative
Christians and others believe that human personhood starts
at conception. Therapeutic cloning would require that the embryo first be
created by cell nuclear replacement, then killed. |
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"...some
argue that the embryo requires and deserves no particular moral attention
whatsoever." 4 They believe that an
embryo is simply a collection of cells containing DNA, not much different
from skin cells that each person sheds by the millions daily. It is not a
human being, not a person. It is composed of a few cells with no internal
organs, arms, legs, sensory organs, brain, or self-awareness. It may
eventually become a person, but only if allowed to mature in a woman's
uterus. They believe that human personhood comes later in gestation, perhaps
when the fetus "looks like" a human, or when its brain
develops to the point where it becomes conscious of itself, or at birth. |
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"Others
accept the special status of an embryo as a potential human being, yet argue
that the respect due to the embryo increases as it develops and that this
respect, in the early stages in particular, may properly be weighed against
the potential benefits arising from the proposed research." 4 |
There appears to be
no hope of reaching a consensus on the ethics of harvesting stem cells from
young embryos. Even within Christianity, Judaism, and other
religions, a range of beliefs exists about when a fertilized ovum
becomes a human person.
Legal
developments:
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1997 - USA:
Commission recommends limitations on creating embryos: The U.S. National Bioethics Advisory
Commission recommended in 1997 that:
The U.S. National Institutes
of Health drafted a set of guidelines in 1999 that:
No limitations
exist for private research, not funded by the government. |
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1998 - Korea:
Researchers at a private company claimed that they had produced the first
cloned human embryo. However, they offered no proof. According to the
National Post: "Most researchers doubted the experiment ever took
place." 7 |
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2000 -
England: Recommendation to lift ban: On 2000-AUG-17, a chief medical officer's expert group
recommended that the government ban be lifted on human "therapeutic
cloning." In England, limited experimentation using young human
embryos is permitted. Therapeutic cloning were seen to not raise "fundamentally
new ethical issues." 2 "Government
ministers have already indicated that they support...[the proposals]. Members
of Parliament will vote on the issue later this year." 2 |
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2001-JUL-30:
USA: House subcommittee approves bill to ban therapeutic cloning: A sub-panel of the House Judiciary
Committee approved a bill sponsored by Representative Dave Weldon (R-FL). It
would ban all human therapeutic cloning for both reproduction and therapeutic
research. It would provide for up to ten years in prison and up to $1 million
in fines for persons who attempt to clone a human being. The Import of cloned
embryos would also be banned. The Biotechnology Industry Group, which
includes almost 1,000 member companies opposes human reproductive cloning,
However. they wrote that therapeutic "cloning techniques in research
are integral to the production of breakthrough medicines, diagnostics and
vaccines." 5 T Their bioethics counsel, Michael
Werner, said "Cloning for research purposes [could] open the door to
the development of cures ... for unmet medical needs like diabetes, stroke
and diseases of aging. Cloning is the way we can figure out how to turn
valuable insights from stem-cell research into products that are
transplantable into patients." The bill is expected to be debated by
the Senate in early 2002. |
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2001-JUL-30:
Europe: Status of therapeutic cloning in the UK and the rest of Europe: Currently, therapeutic cloning of humans
is banned in 29 European countries, but is permitted in the UK for research
purposes. In 1991, the UK Parliament established the Human Fertilization
and Embryology Authority, which licenses both fertility clinics and
research institutions that study embryos. To date, the agency has allowed 118
embryos to be created for research purposes -- none yet for therapeutic
cloning. However it has the authority to approve that form of cloning. "In
the past decade, 925,747 [embryos] have been created and more than 50,000
babies have been born; 294,584 embryos have been destroyed and 53,497 have
been used for research." 6 If therapeutic cloning is
banned in the U.S., there would probably be an immediate "brain
drain" of American medical researchers to the UK. |
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2001-NOV-25:
USA: Company successfully produced human clone: Advanced Cell Technology, a biotech
company in Worcester, MA, announced that they had produced an embryo with
human DNA which had grown to the six-cell level. The company's chief
executive officer, Michael West, told NBC's Meet The Press that if the
embryo had been implanted in a woman's womb, it might have developed into a
newborn. However, the technology will be used only to generate stem cells for
research. Mary Ann Liebert, publisher of the online journal e-biomed,
said: "New technologies are frequently controversial and I think people
right away think 'Oh my God, we're going to clone a human being,' but that is
not what this is about. It will be sad and tragic if this does not go ahead."
7 |
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2001-JAN-29:
USA: Company creates kidney-like organ via therapeutic cloning: Scientists at Advanced Cell
Technology in Worcester, MA have proven the principle of therapeutic
cloning. They took a cell from a cow's ear, inserted its DNA into a cow ovum
which had its DNA removed, grew stem cells, extracted the cells, and produced
a number of kidney-like cow organs. When implanted into the original cow,
they were not rejected. They started to function like ordinary kidneys and
produced urine. The impact of this development on humans suffering from
kidney disease is immense. If the technology will work on humans, it would dramatically
reduce the need for donor kidneys and transplants; fewer people would die;
persons suffering from kidney disease would lead much improved lives. This
development comes at a critical time, politically. The House has passed a
bill that would criminalize both reproductive cloning (the production of
cloned babies) and therapeutic cloning (the production of cloned organs). The
Senate is debating a bill that would ban reproductive cloning but permit
therapeutic cloning. 8 |
Related
essay on this website:
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Menu: Cloning - all aspects |
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References:
1.
"Comment:
Stem Cell Research," Mary Woodard Lasker Charitable Trust, at: http://www.fundingfirst.org/comment/16/comm2.html
2.
"British
experts back cloning," 2000-AUG-16, at: http://www.7am.com/cgi-bin/twires.cgi?
3.
"Stem
cell research: Medical progress with responsibility," Chief medical
officer's expert advisory group on Therapeutic Cloning," at: http://www.doh.gov.uk/cegc/
4.
"A
report from the chief medical officer's expert group reviewing the potential of
developments in stem cell research and cell nuclear replacement to benefit
human health," Department of Health (UK), at: http://www.doh.gov.uk/cegc/stemcellreport.htm
The report is available as an executive summary or as full report in PDF
format. You can obtain a free software to read PDF files from Adobe.
5.
Todd Zwillich,
"House subcommittee approves ban on human cloning," at: http://www.reutershealth.com/
6.
"Embryo,
stem cell research moving full bore in Britain," New York Times, at: http://new.omaha.com/index.php?
7.
Tom Arnold,
"Embryo research raises issues of morals, ethics: Laws on human
replication lagging behind science," National Post (Canada),
2001-NOV-26. See: http://www.nationalpost.com/artslife/life/health/
8.
Rick Weiss,
"Scientists Claim an Advance in Therapeutic Cloning: Mass. Firm Uses
Embryonic Cow Cells to Create Kidney-Like Organs; Transplant Success Reported,"
Washington Post at: http://www.washingtonpost.com/wp-dyn/
Copyright
© 2000 to 2002 incl., by Ontario Consultants on Religious Tolerance
Originally published: 2000-AUG-17
Last
updated 2002-JAN-31
Author:
B. A. Robinson
