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American researchers have cloned human embryos in an experiment aimed
at adding new options to the armoury of the fertility clinic. In this experiment,
the researchers deliberately used defective embryos to ensure that the clones
died within a few days. The researchers say they have no intention of trying
the technique on normal embryos or of implanting cloned embryos into women.
But the experiment has raised a host of ethical questions.

Researchers from the George Washington University Medical Center, led
by Jerry Hall and Robert Stillman, described their work earlier this month
at the joint annual meeting of the American Fertility Society and the Canadian
Fertility and Andrology Society. They performed the experiment on embryos
obtained from women undergoing IVF treatment. These embryos had a fatal
defect. They were formed from eggs fertilised by more than one sperm, giving
them three or more sets of chromosomes instead of two. ‘We used these triploid
embryos so as not to get into an ethical debate,’ says Hall. ‘Somebody was
going to do this research. You can’t stop science. We thought it would be
best if it was done in a successful IVF research programme like ours.’

The researchers split 17 embryos, made up of between two and eight cells
each, and then coated the individual cells with a gel-like substance to
form an artificial zona pellucida, the protective membrane around an embryo.
The most successful clones, which reached the 32-cell stage before dying,
developed from embryos which had been split at the two-cell stage.

Stillman, director of the hospital’s IVF programme, says the ultimate
goal of the work is to ‘reproduce nature’s ability to produce twins’ and
so help women with low fertility to bear children. At present, IVF centres
give a woman hormones that cause her to ‘superovulate’, producing several
ripe eggs at once. These eggs are surgically removed and fertilised outside
the body, producing several embryos that can be implanted to improve the
chances of a successful pregnancy. The researchers at George Washington
University see embryo cloning as a way to produce multiple embryos without
the cost or the side effects associated with hormone treatment. Earlier
this year, one study tentatively linked induced superovulation with ovarian
cancer.

The US has no national policy or agency regulating embryo research,
although a long-standing ban on federal funding for such research was lifted
by President Clinton when he came into office. ‘We went through a period
under Bush and Reagan when you couldn’t even talk about fetal research,’
says Gail Povar, head of the ethics committee at George Washington Hospital.
‘We’re now entering a somewhat different era in the US when you can begin
to discuss it rationally.’

Povar’s ethics committee, including a minister, a philosopher and a
lawyer as well as medical professionals and social workers, approved the
cloning experiment. ‘They felt that at this stage, the pre-embryo does not
represent a potential human being because it has not sufficiently differentiated,’
says Povar.

The fact that the experiment would use embryos with lethal defects was
also important in gaining the committee’s approval. ‘What we’re talking
about here is nonviable human chromosomal tissue,’ says Povar. ‘I don’t
consider this to be human cloning. I consider it the manipulation of pathological
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However, the committee was very aware of the ethical implications of
the research. If viable cloned embryos were frozen, parents could give
birth to a ‘twin’ at a later date, perhaps to replace a dead child, or
to provide bone marrow or other organs for a sick child. The idea of giving
birth to a ‘twin’ in order to gain access to spare parts ‘violates most
of our Kantian views about humanity, about not using human beings as a
means to an end’, says Povar.

In Britain, embryo splitting is illegal, says Veronica English of the
government’s watchdog on IVF clinics and embryo research, the Human Fertilisation
and Embryology Authority. In July, the authority decided that splitting
human embryos is ‘ethically unacceptable’, says English. ‘We would not
grant a licence for the practice, thus making it illegal for anyone to split
human embryos in this country.’

Splitting human embryos is ‘misguided and probably counterproductive
in any case’, according to Alan Handyside, a senior embryologist at the
Hammersmith Hospital in London. Far from increasing the chances of an embryo
successfully implanting into the woman’s uterus, the operation would probably
reduce them, he argues. Implantation rates decline rapidly in mouse embryos
that have been experimentally divided, he says.

Splitting human embryos might also increase the risk of multiple births,
says Handyside. These are known to be linked to higher rates of infant death
and disability, and to threaten the mother’s health.