Human cloning
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Human cloning is the creation of a genetically identical copy of an existing human or growing cloned tissue from that individual. The term is generally used to refer to artificial human cloning; human clones in the form of identical twins are commonplace, with their cloning occurring during the natural process of reproduction.
Note that cloning is not limited to humans. However, this article is only about the artificial cloning of human beings.
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Understanding cloning
The meaning of human cloning is often misunderstood. Although genes are recognized as influencing behavior and cognition, "genetically identical" does not mean altogether identical; almost no one would deny that identical twins, despite being natural human clones with identical DNA, are separate people, with separate experiences and not altogether overlapping personalities. However undramatic it may sound, the relationship between an "original" and a clone is rather like that between identical twins raised apart; they share all the same DNA, but little of the same environment. A lively scientific debate on this exact topic occurred in the journal Nature in 1997. (http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9144274&dopt=Citation)
Ultimately, the question of how similar an original and a clone would be boils down to how much of personality is determined by genetics, an area still under active scientific investigation. (See Nature versus nurture and clone (genetics).)
Techniques
Currently the most successful cloning technique is the same process which allowed Dolly the sheep to be cloned - somatic cell nuclear transfer. It is also the technique used by ACT, the first company to successfully clone a human embryo (see research section below). An egg cell taken from a donor has its nucleus removed. Another cell with the genetic material to be cloned is fused with the original cell.
Another way of cloning is by parthenogenesis, where an unfertilized egg cell is induced to divide and grow as if it were fertilized. This technique only works on females.
In reproductive cloning, the cloned embryo is implanted in a woman's uterus. This should develop into a normal baby, its only distinction being that it would be almost genetically identical to the DNA donor.
Therapeutic cloning could be used to provide replacement organs or tissue for people who have had theirs damaged. The cloned embryo would contain DNA taken from the transplant patient. After nuclear transfer, the cell would divide to form an embryo and stem cells would be removed. Stem cells could develop into any tissue or organ. These cloned organs would be compatible with the person's immune system, so no immunosuppressant drugs would have to be taken after the operation. However, no therapies have been developed yet from this procedure.
Limits of cloning
First, none of these techniques provide exact clones -- they would be 99.7% identical to the DNA donor, because some important genes are present outside the nucleus, in mitochondria for example. Some of the DNA of the DNA donor would be missing for the clone to be an exact copy, and some of the resulting clone DNA would come from the donor egg-cell. How much change this would lead to in the clone is being investigated, but it could spell problems for therapeutic cloning, where compatibility is essential because of the risk of rejection.
Second, difficulties with cloning organisms from their somatic (non germline) cells tend to lead to (what seems to be) premature aging in higher animals. If a new brain is generated in that body, there is no reason to believe that consciousness, apart from the ethics of the move, can ever be moved from one brain into a new brain even if it is genetically identical. Identical twins often show uncanny parallels in life choices, but rarely do they exhibit any characteristics that would cause one to believe that genetic similarities in brains lead to any kind of compatibility of consciousness. If a brain is moved from an old body to a new one, even a clone, it would continue to lose size and capacity to regenerate cells, and continue to be subject to such disorders as Alzheimer's disease. Given all this, 'immortality' seems a difficult goal to achieve, and even extended lifespan may be at a low quality of life.
Given these limits, the main reason for interest in the speculations is that they may be driving funding for research, and providing active lobbying for legal or political protections for the cloning industry. Concerns regarding the Raelian movement tend to focus on this issues.
The current status of cloned-embryo research
In 1998, South Korean scientists claimed to have created the first cloned human embryo, but the results were never published and many doubt that they had done so.
In the November 25, 2001, issue of the Journal of Regenerative Medicine, a US company Advanced Cell Technology claimed that it had successfully created a clone of a human, in the form of an embryo. ACT vice president Dr. Robert Lanza said that the company's intention was to use this in therapeutic cloning, in order to harvest embryonic stem cells from a patient.
Some scientists objected that the ACT cloning had not actually been successful because the cloned embryos had only divided a few times, meaning it was possible that the transplanted genetic material had not actually been used. Further criticisms were of the company's inability to collect much useful information from the experiment, and of their inability to harvest stem cells. The company stressed that it was against reproductive cloning and they hoped to develop purely therapeutic processes.
In 2004, a group of scientists led by Woo Suk Hwang of Seoul National University in Korea claimed to have grown 30 cloned human embryos to the one-week stage, and then successfully harvested stem cells from them. The results of their experiment were published in the peer-reviewed journal Science. This technique, however, was widely regarded as too time-consuming and difficult to be clinically useful [1] (http://www.medicalnewstoday.com/medicalnews.php?newsid=24835).
In May 2005, Hwang's team announced the creation of 11 lines of human stem cells, using a different technique (Hwang et al. 2005). Using this technique, the team was able to develop stem cells for use in treating specific patients. This appears to open the door to therapeutic cloning. This discovery added urgency to the global ethical debate on stem-cell research, and brought condemnation from conservative leaders including George W. Bush [2] (http://english.chosun.com/w21data/html/news/200505/200505220006.html) and Vatican prelate Elio Sgreccia [3] (http://www.cwnews.com/news/viewstory.cfm?recnum=37270).
Risks of growing a cloned embryo to term
Reproductive cloning has supporters such as the scientists Panayiotis Zavos, Brigitte Boisselier, and Severino Antinori. Antinori had claimed that a cloned baby would be possible before 2003. However, the majority of scientists, including Ian Wilmut, who led the team that cloned Dolly the sheep at the Roslin Institute, claim that there are many further complications to reproductive human cloning in its curent form. Aside from the ethical questions involved, the scientists claim that it is simply too risky. In a debate for the American National Academy of Sciences Wilmut quoted the low survival rate of cloned animals as evidence that human cloning would be dangerous. The main fears are that children will be born with genetic disorders, which might develop or worsen over the years.
Zavos thinks that by screening embryos before and after implantation this risk would be reduced significantly. Don Wolf, a researcher at Oregon Regional Primate Research Centre, disagrees. He suggests that screeners would not even know what to look for.
Zavos works with the Italian infertility expert Severino Antinori, who was recently expelled from the International Association of Private Assisted Reproductive Technology (APART) for his well-publicized wish to be the first to clone a human. Antinori claims that cloning humans would actually be safer than in animals. He quotes research from Duke University, which seems to suggest a vital genetic difference between primates and other animals with regard to cloning. A problem discovered when cloning was first developed was that many of the clones grew much too large in the uterus, consequently dying at birth. A researcher at the university, Randy Jirtle, suggests this is due to the growth controlling gene IGF2R being suppressed. In animals a process known as imprinting can cause this gene not to be expressed. If the remaining gene is also turned off then 'large offspring syndrome' (LOS) occurs. Research he has done suggests that in primates neither gene can be subject to imprinting. Jirtel thinks that because of these extra safeguards, reproductive human cloning would be much safer than cloning of other mammals.
This is disputed by scientists who say that large-offspring syndrome is just one of many problems that result from cloning. Controlling this gene would not prevent many other genetic disorders which have yet to be fully understood or discovered.
Zavos and Antinori also say that the many of the developmental problems in animals were due to non-ideal conditions in which the embryos were cultured. Researchers at the Whitehead Institute for Biomedical Research, MIT, have found that this disrupts genes so that apparently normal-looking animals die early. Zavos points out that reproductive science is actually more advanced in humans due to the widespread use of treatments such as in vitro fertilisation (IVF), and therefore cloning in humans is not such a large step as animal cloning was.
The Whitehead team, however, conclude that reproductive human cloning is not a good idea. They did suggest, though, that therapeutic cloning of organs should be safer. This is because the imprinting experienced during culture is less important when cells specialize and start to grow in to specific tissues.
Claims of success in human cloning beyond the embryo stage
In 1978 David Rorvik claimed in his book In His Image: The Cloning of a Man that he had personal knowledge of the creation of a human clone. A court case followed. He failed to produce corroborating evidence to back up his claims, and his claims are now regarded as a hoax.
Severino Antinori made claims in November 2002 that a project to clone human beings has succeeded, with the first human clone due to be born in January 2003. His claims were received with skepticism from many observers.
In December 2002, Clonaid, the medical arm of a cult called Raelism, who believe that aliens introduced human life on Earth, claimed to have successfully cloned a human being. They claim that aliens taught them how to perform cloning, even though the company has no record of having successfully cloned any previous animal. A spokesperson said an independent agency would prove that the baby, named Eve, is in fact an exact copy of her mother. Shortly thereafter, the testing was cancelled, with the spokesperson claiming the decision would ultimately be left up to Eve's parents.
A mother in America plans to pay $500,000 to the Clonaid organisation to clone her deceased daughter. In December 2004 Dr. Boisselier, claimed in letter to the UN that Clonaid has successfully cloned 13 children, however their personalities cannot be revealed to the public in order to protect them.
Dr. Panos Zavos claimed on January 17, 2004 to have successfully produced a two week old cloned embryo which he attempted to implant into a 35 year old woman. However, the woman did not become pregnant.
Possible advantages
Many hopes have been put upon human cloning. Therapeutic cloning could provide needed organ transplants. A cure for cancer by a better understanding of the cell-differentiation process, as well as better treatments for heart attacks and improved cosmetic surgery, are being cited as being possible with the new technology. Dr. Richard Seed thinks that human cloning will help us understand, and eventually reverse, the human aging process.
Antinori and Zavos hope to create a fertility treatment that allows parents who are both infertile to have children with at least some of their DNA in their offspring. Some families have high hopes for reproductive cloning. How to Build a Human, a documentary by BBC and Discovery Channel, illustrated the prospects by showing an American family that wants to make a clone of their third child, who, although genetically healthy, had serious mental and physical deficiencies due to complications at birth and is expected to die soon. Other people hope to clone their already deceased children.
In Science Fiction, Clones have been seen as Expendable Soldiers in the Military.
The current law on human cloning
In 1998, 2001, and 2003 the US House of Representatives voted to ban all human cloning, both reproductive and therapeutic. Each time, divisions in the Senate over therapeutic cloning prevented either competing proposal (a ban on both forms or reproductive cloning only) from passing. President George W. Bush is opposed to human cloning in any form. Some states ban both forms of cloning, while some others outlaw only reproductive cloning.
Current regulations prohibit federal funding for research into human cloning, which effectively prevents such research from occurring in public institutions and private institution such as universities which receive federal funding. However, there are currently no laws in the United States which ban cloning completely, and any such laws would raise difficult Constitutional questions similar to the issues raised by abortion.
The British government introduced legislation in order to allow licensed therapeutic but not reproductive cloning in a debate in January 2001 after an amendment to the Human Embryology Act. However on November 15, 2001 opposition groups won a High Court legal challenge that effectively blocked cloning of embryos for therapeutic purposes. They discovered a loophole which allows reproductive cloning to be performed also. Anti-abortion groups say that a new debate is necessary because of recent technologies having been developed that might circumvent the need for embryonic cloning. The government overruled this attempt at the beginning of March 2002 and currently therapeutic cloning is allowed under license of the Human Fertilisation and Embryology Authority. The first known licence was granted on August 11, 2004 to researchers at the University of Newcastle to allow them to investigate treatments for diabetes, Parkinson's disease and Alzheimer's disease.
Australia has a government committee still considering the issues, having already introduced a variety of regulations on cloning in general. However organisations devoted to clone humans, such as the Raelites and the Las-Vegas based Clonaid, as well as Antinori and Zavos, are very hard to control. Many think these groups would shift their operations to other countries, many 3rd world countries have no such ban on cloning, so there may, not likely, be some cloning of humans there.
The United Nations has been debating a global treaty to ban human cloning. Lawrence Goldstein, professor of cellular and molecular medicine at the University of California at San Diego, says that the United States, unable to pass a national law, forced Costa Rica to start this debate in the UN over the international cloning ban.
So far, as in the United States Congress, divisions over therapeutic cloning have prevented any proposal from making significant progress. In November 2004, after several postponements to a vote on the treaty, the proposed ban, together with a Belgian proposal that would have allowed therapeutic cloning, was shelved due to lack of consensus. Further discussion on the issue, will take place in February 2005.
Human cloning in fiction
Human cloning has long been a subject of speculation in science fiction. Science fiction speculation has included:
- the use of cloning for "spare parts" for transplantation, typically with accelerated growth of the cloned parts
- transferring one's mind into a younger clone body, as a way of achieving immortality
- clones somehow having a telepathic affinity for one another
Apart from the first, these ideas are currently pure speculation, with no basis in reality.
References
- Hwang WS, et al. (2004). Evidence of a Pluripotent Human Embryonic Stem Cell Line Derived from a Cloned Blastocyst. Science. 2004 Feb 12 [4] (http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=14963337&dopt=Abstract)
- Hwang WS, et al. (2005). Patient-Specific Embryonic Stem Cells Derived from Human SCNT Blastocysts. Science Express. 2005 May 19. [5] (http://www.sciencemag.org/cgi/content/abstract/1112286v1) Document ID: 10.1126/science.1112286
See also
- Cell incubator
- Cloning
- Genetics
- Genetic engineering
- Stem cell
- Therapeutic cloning
- Utilitarian Bioethics
External links
- New Scientist's recent articles on stem cells and cloning (http://www.newscientist.com/hottopics/cloning/cloning.jsp)
- Advanced Cell Technology: The company that performed the first cloning of a human embryo (http://www.advancedcell.com/)
- Ethics of human cloning (http://www.puaf.umd.edu/IPPP/Fall97Report/cloning.htm)
- http://www.humancloning.org - a pro-human cloning website, opinionated.
- Article about David Rorvik claims (http://www.museumofhoaxes.com/cloning.html)
- Human Cloning Prohibition Act of 2003 (http://thomas.loc.gov/cgi-bin/bdquery/z?d108:s.00245:) -- Proposed US legislation to ban cloning
- Time Magazine's profile of Woo Suk Hwang and his lab (http://www.time.com/time/magazine/article/0,9171,1064420,00.html)pl:Klonowanie ludzi