Magazine
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News focus
Death of Dolly marks cloning milestone
Dolly the cloned sheep marked both an icon of scientific possibility and to term. Dolly’s genetic mother
a potential ethical nightmare. Researchers in related fields of stem cell (the DNA was taken from an udder
research need to learn the lessons and the right vocabulary if they are cell) was six when she was
to make progress in their fields. Nigel Williams reports. cloned. This may mean that the
real age of clones is their age
Dolly the sheep, the world’s first on the significance of the ewe’s since birth, plus the age of the
mammal to be cloned from an death. ‘Sheep can live to 11 or 12 genetic donor.
adult cell was put to sleep last years,’ he said. ‘Lung infections The revelation to the world of
month. She was only six and a half are common in older sheep, Dolly’s existence, in 1997, was the
years old – barely 40 in human particularly those housed inside. A scientific sensation of the decade.
terms. Already being treated for full postmortem is being Scientific orthodoxy declared that
arthritis, Dolly was found to be conducted and we will report any cloning mammals was impossible:
suffering from a progressive lung significant findings.’ After the here was the proof. A frenzy of
disease. postmortem examination, Dolly speculation followed about what
The premature death of Dolly will be stuffed and put on display cloning could achieve. But it is
supports the view of some at the National Museum of now known that cloning is
scientists in Japan and the US Scotland. difficult, expensive and
who maintain that all cloned Dolly was born on July 5 1996, dangerous for the animals
animals are born with health from three mothers: one ewe to involved. Claims of cloned
problems. Harry Griffin, provide the DNA, another to humans remain unproven.
spokesperson for the Roslin provide the egg into which the Speculation about its potential
Institute, near Edinburgh, where DNA was injected, and a third to came quickly back to earth with
Dolly was created, was cautious carry the resulting cloned embryo the announcement that Dolly had
Goodbye Dolly: The creation of a cloned sheep caused a media sensation but her death demands a rethink of attitudes and presen-
tation of cloning and related stem cell research. (Picture: Science Photo Library.)
Current Biology Vol 13 No 6
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developed arthritis, which is the major obstacles to stem-cell Molecular Medicine, at Oxford
highly unusual in a sheep of her therapy with cells derived from University.
age. embryos or adult sources is that, Many countries are finding it
Speaking to reporters from unless they came from a difficult to sort out these ethical
Dolly’s pen at the Roslin Institute, compatible donor, they would be issues and to define a code of
the head of the original cloning treated as ‘foreign’ and rejected practice for work in the stem cell
team, Ian Wilmut, put a brave face by a patient’s immune system. field. In the UK, after an extensive
on the sheep’s condition. One way round this problem study followed by a report from
He said he was concerned and would be to transfer a cell the chief medical officer’s expert
called for more research into the nucleus from an individual into an group, and wide debate in
implications of cloning. But he egg from which the nucleus has parliament, it is permissible to use
insisted that the technology was been removed, after which the human embryonic stem cells
crucial for medical science and newly created ‘embryo’ would be derived from ‘leftover’ embryos
denied that he had opened a used as a source of embryonic not required by the genetic
Pandora’s box by showing that stem cells for regenerative parents for reproduction, or from
mammals can be cloned. “This is therapy for that person. This embryos created for research
an inefficient procedure. We were technique, called somatic cell purposes by in vitro fertilization,
always aware that there was a risk nuclear transfer, does, of course, or the nuclear transfer technique,
that we would find things like this. follow exactly the same steps as for specifically defined areas of
We were very disappointed and would be required for human research. The legality of this
very concerned for the animals,” reproductive cloning. Since there position is still questioned by
he said. would be no intention of placing those who oppose any form of
“We will never know in the case an egg treated in this way into a research on embryos.
of Dolly whether the condition is uterus, the objectives of the In Germany, research on human
because she is cloned or whether procedure would be completely embryonic stem cells was
it is an unfortunate accident that different. But researchers have prohibited, although it is allowed
she developed arthritis. What’s been caught in the ethical trap of in exceptional cases, provided it
very important is that not only we scrutiny of procedures that can is carried out on imported stem
at the institute, but others who be used for entirely different ends cells derived before January 2000
produce cloned animals should and many now believe the way from surplus embryos.
monitor their health throughout forward lies in distinguishing to In the US, President Bush
their entire life span.” the public what the goals of announced in August 2001 that
Animal cloning is already known different research programmes federal funding for research in this
as an unreliable and risky are. field could be used only for work
procedure. It took 276 It is clear then that, while stem on 60 stem-cell lines that had
unsuccessful attempts before cell research is still at an early been derived from excess human
Dolly was produced. Many cloned stage of development and there embryos before his
animals which are carried to term are many uncertainties, enough is announcement. There is, however,
die shortly after birth and suffer known already to suggest that the no federal law or policy
deformities. The University of medical benefits of a better prohibiting the private sector from
Missouri team implanted 3,000 understanding of stem-cell creating stem cells by in vitro
embryos in 28 surrogate sows to biology might be considerable. fertilization or nuclear transfer.
get just seven piglets. But it cannot be advanced without Some of these issues are
“We must await the results of a source of human embryos. described in a recent account of
the postmortem on Dolly in order While it has been suggested stem cell research, based on the
to assess whether her relatively that a better understanding of the assessment and work of a
premature death was in any way properties of embryonic stem committee chaired by cancer
connected with the fact she was a cells could be achieved by work in researcher Bert Vogelstein, under
clone,” said Richard Gardener, the mouse and other animals, it is the auspices of the US National
chairman of the Royal Society already clear that there are many Research Council. “The NRC
working group on stem cell differences between species in report reminds us how difficult it
research and therapeutic cloning. the properties of these cells. is to develop an ethical
“If there is a link, it will provide “It is not surprising that this framework for a research field
further evidence of the dangers field has caused and still causes that is so full of uncertainties and
inherent in reproductive cloning considerable controversy. It is potentials, and one in which the
and the irresponsibility of anybody particularly unfortunate that the technology skates close to
who is trying to extend such work term ‘therapeutic cloning’ has activities that are repugnant to
to humans.” been applied in an uncritical and many people. But one thing this
The drama surrounding the blanket fashion. It is difficult to increasingly bitter debate has
creation of Dolly has had knock- dissociate it in people’s minds already made clear is that
on effects for other areas of from reproductive cloning, the scientists must be much more
research that may involve similar objective of which is totally precise, and less emotive, in the
techniques of nuclear transfer, different,” says David Weatherall, language they use to describe
such as stem cell therapy. One of former head of the Institute of what they do,” says Weatherall.
