Mixed-sex human embryo created

[Dave Farber <dave () farber net>]

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From: Dewayne Hendricks <dewayne () warpspeed com>
Reply-To: dewayne () warpspeed com
Date: Thu, 03 Jul 2003 06:10:34 -0700
To: Dewayne-Net Technology List <dewayne-net () warpspeed com>
Subject: [Dewayne-Net] Mixed-sex human embryo created


  Mixed-sex human embryo created
By Martin Hutchinson
BBC News Online health staff in Madrid
An experiment in the United States has created a mixed-sex human embryo.

The team involved insists that the creation of an hermaphrodite human
embryo was designed to cure illness, but critics say moral and
ethical standards have been breached.

The process they used creates what is known as a "chimaera" - a blend
of two embryos, each of which would have a distinct genetic
identities.

But any attempt to produce such a baby would provoke a worldwide ethical
storm.

In experiments using donated embryos, scientists from the Centers for
Human Reproduction in New York and Chicago investigated whether
healthy cells from one embryo could be implanted into a second
defective embryo.

They found that, in some cases, the introduced cells do proliferate
and spread throughout the chimaeric embryo.

Their hope is that having even a small proportion of cells from a
healthy embryo might prevent certain genetic diseases from arising.

The "merged" embryos were never intended to develop into children,
and were destroyed after a few days.

However, other experts have dismissed the idea as "deeply flawed" -
and say research into the issue, even in animals, should not continue.

Any use of chimaeric technology in human reproduction in the UK is illegal.

Dr Norbert Gliecher, who led the research, told the European Society
for Human Reproduction and Embryology annual meeting in Madrid: "It
is not ready for clinical application in humans - I don't want to
suggest that.

"But further exploration in animals is warranted - and who knows
where this will take us?"

Joined up

The potential for cells from two different embryos to fuse and become
one "combination" individual is well known in nature - there have
been examples where this has happened in early pregnancy in humans,
with no apparent ill-effects on the resulting baby.

The theory behind Gliecher's work is that some studies have suggested
that in certain diseases caused by a single genetic defect, having
even as few as 15% of the body's cells free from the defect might be
enough to stop the development of the disease.

He said his experiment showed that just a couple of cells injected
into the embryo produced an embryo with, in many cases, an even
distribution of cells carrying these new genes.

He deliberately injected a male cell into a female embryo - which
created an "intersex" embryo, but allowed him to use chemical tests
to check the process of the chromosome unique to male cells.

Gleicher said that a couple having embryos screened for a single-gene
disease such as Severe Combined Immunodeficiency Disorder (SCID)
might end up with two embryos, one of which had the disease and one
which did not.

In this instance, he said, it might be possible to take cells from
the "good" embryo and put them into the defective one, producing two
viable embryos, whereas previously, the defective one would have to
be discarded.

However, his experiment was roundly attacked by senior scientists at
the conference.

'No logic'

Professor Alan Trouson, a pioneer of IVF in Australia, told BBC News
Online: "I really can't see the logic of what he is trying to do - it
seems completely flawed to me."

He said that it would be impossible to test whether the correct
versions of the genes had been incorporated widely into the embryo
before a decision had to be made whether to transfer it back into the
woman.

He said that the health risks of producing a chimaeric individual
were still uncertain.

"Unless you can be certain you are doing some good, you should not be
doing something that could cause harm."

He said that the US team should not even attempt to continue their
experiments in animals.

Professor Lyn Fraser, a past president of the society, told the BBC
that she shared the disquiet over the technique.

She said: "I don't see how it can be used to treat single gene
disorders. It's hard to accept what they have done at all."

Story from BBC NEWS:
http://news.bbc.co.uk/go/pr/fr/-/2/hi/health/3036458.stm

Published: 2003/07/03 04:45:17 GMT

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