NEXT month, it will be three years since researchers at the Roslin Institute
near Edinburgh presented Dolly the sheep to an unsuspecting world. The news
stunned both the public and biologists. Today, many countries are still debating
how鈥攁nd even whether鈥攖he cloning technology that created Dolly
should be applied to humans.
Hairs on necks still bristle when human cloning is mentioned. It stirs up
feelings that scientists are going too far in 鈥渕eddling with Nature鈥� or that
they are cheapening human life. Many religious groups also harbour specific
objections because of cloning鈥檚 dependence on human embryos.
Yet, there now seems less to worry about than first appeared. Only an extreme
fringe wants to use cloning to make copies of people, and such uses should be
banned where they鈥檙e not already. But many researchers see enormous potential in
鈥渢herapeutic cloning鈥濃�� the notion of growing tissue for patients that is
genetically identical to their own. Neural cells could be made for people with
Parkinson鈥檚 disease, new muscle for those with ailing hearts and, later, perhaps
even whole organs might be grown, all free from the threat of tissue
rejection.
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In the face of such potential, why are governments and other regulators
making such heavy weather of human cloning? Last year, the British government
attracted widespread derision when it rejected the recommendations of its own
advisers and set up yet another committee to examine cloning. And only now are
the National Institutes of Health in the US coming to the end of a public
discussion on draft guidelines for research into stem cells鈥攖he cells in
early embryos that can develop into any type of human tissue.
In Australia, state governments have introduced a variety of regulations to
cover cloning, while a federal government committee is still considering all the
issues. Similar inquiries are going on across Europe. What, then, is so
controversial?
To make Dolly, the Roslin researchers removed the nucleus from an egg and
fused what was left with an udder cell from a six-year-old ewe. Astonishingly,
proteins in the egg鈥檚 cytoplasm stripped the udder cell of its genetic controls
and returned its DNA to an embryonic state. The resulting cell then began to
divide like a normal embryo.
For therapeutic cloning, researchers want to fuse a denucleated egg with a
patient鈥檚 cell and let it grow for a few days. Then they would extract the stem
cells and use them to grow the required kinds of tissue.
This seems an important use for human cells. Already, early
embryos鈥攚ithout even a semblance of a nervous system鈥攁re donated for
certain areas of research. In Britain, those fields include infertility,
contraception and the causes of miscarriage. Is research into making tissue for
salvaging and saving lives any less worthy?
Thousands of surplus embryos produced for IVF are also destroyed every year.
So objections to therapeutic cloning on the grounds that embryos should not be
created and destroyed in the lab would apply just as much to these permitted
practices.
Though these may be established procedures, they still raise strong emotions.
And, with the public already sensitive about other aspects of biotechnology,
regulators are wary of pushing ahead too fast.
So the latest news from the Roslin is likely to be seized on with relief.
Researchers there believe that therapeutic cloning could be done without
destroying human eggs or embryos
(see 鈥淐loning Without Embryos鈥�).
They are trying to create stem cells
directly by adding the nucleus of an adult cell to denucleated embryonic stem
cells.
This would remove many of the ethical objections to cloning鈥攖hough not
all of them. Researchers would still need to use stem cells, derived from
embryos. Such cells, however, are now growing in the lab, so few, if any,
embryos would need to be destroyed to obtain more of them.
The Roslin researchers say that to begin with they will still need to perform
cloning using human eggs and embryos. But the prospect that therapeutic cloning
could eventually be done without them may ease the pressure on those deciding
how to regulate it.
Whether or not this new technique can be made to work, it is time to approve
therapeutic cloning. If regulators don鈥檛 decide soon, there is a strong chance
that some researchers will head for countries where there are no rules governing
cloning. This would be a shame. We need to make sure that therapeutic cloning
develops in a safe and sensible way.
