Human-pig hybrid embryos given go ahead
Pastor Dale Morgan
Human-pig hybrid embryos given go ahead*
By Roger Highfield, Science Editor
Last Updated: 12:01am BST 01/07/2008
A licence to create human-pig embryos to study heart disease has been
issued by the fertility watchdog.
This marks the third animal-human hybrid embryo licence to be issued by
Human Fertilisation and Embryology Authority and the first since the
Commons voted in favour of this controversial research last month.
An HFEA spokesman said it had approved an application from the Clinical
Sciences Research Institute, University of Warwick, for the creation of
hybrid embryos. The centre has been offered a 12 month licence with
effect from today, July 1.
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The effort at the University of Warwick is led by Professor Justin St
John. "This new license allows us to attempt to make human pig clones to
produce embryonic stem cells," he said, where embryonic stem cells are
able to turn into the 200 plus types in the body.
"We will take skin cells from patients who have a mutation for certain
kinds of heart disease (cardiomyopathy, which makes the heart lose its
pumping strength) and put them into pig eggs after their chromosomes
have been removed. We will then make embryos so that we can attempt to
derive embryonic stem cells which will allow us to study some of the
molecular mechanisms associated with these heart diseases.
"Ultimately they will help us to understand where some of the problems
associated with these diseases arise and they could also provide models
for the pharmaceutical industry to test new drugs. We will effectively
be creating and studying these diseases in a dish.
"But it's important to say that we're at the very early stages of this
research and it will take a considerable amount of time. There is still
a great deal to learn about these techniques and much of our early work
will involve understanding how we can make the hybrid cloning process as
efficient as possible."
The study is aimed at understanding the way power-producing structures
in cells, called mitochondria, are passed from egg to embryo. In the
hybrid, the mitochondria mostly come from the egg, initially making up
around half of the DNA by weight, and the team will do experiments in
order to ensure that the trace of human mitochondrial DNA takes over,
not least because it is designed to work with human nuclear DNA.
"The key thing we are doing is trying to create stem cells without any
animal DNA in them. So even though these hybrid embryos normally have a
small percentage of animal DNA , we are hoping to create cells that
would have human chromosomes and human mitochondrial DNA." The reason is
that, as the team puts it, "mixing of these two diverse populations of
mitochondria can be detrimental to cellular function."
Dr Evan Harris, Liberal Democrat science spokesman, commenting on the
HFEA decision to issue a license to the University of Warwick to create
hybrid embryos combining human skin cells with enucleated pig eggs,
said: "This application is a further indication of the interest in this
sort of research by UK scientists, the decision of the HFEA to issue a
license following stringent checks demonstrates that it is considered
both necessary and ethical."
"While this approval comes under the existing 1990 Human Fertilisation
and Embryology Act, both houses of Parliament have recently voted by
large majorities to allow it into the future," said Prof Robin
Lovell-Badge, of the MRC National Institute For Medical Research.
"It is good news that this license has been issued at a time when
parliament has expressed overwhelming support for this research after an
excellent public debate. I suspect other similar applications will
follow and hopefully this research can now progress without the hype."
Teams in Newcastle and London are already creating hybrids. The former
have already created hybrids with cow eggs to study the basics of how
the use of genes changes in early development, the latter a range of
species to generate stem cells from people with neurodegenerative
disorders.