Monday,8
May, 2000
Following The Herd
You've met Dolly the sheep
and read about pig cloning, now please welcome the super cow.
Science In Action presenter Richard Black spoke to Dr
Robert Lanza, from the Advanced Cell Technologies (ACT) of Worcester,
Massachusetts, about the future of genetically engineered cows.
Dolly
the sheep was the first ever cloned mammal and when the world
heard about her, the media went wild. At this time there was
a great deal of speculation about the uses of cloning; culminating
in the ultimate fear that one-day man would clone a human. Four
years on from Dolly and cloning fever has quietened down. Until
now when scientists claim to be able to reverse the ageing process
in animal cells - a technological advance that may eventually
enable them to grow rejuvenated cells with which to replace
dead or damaged tissues.
Procedure
The process carried out was relatively similar to that carried
out on Dolly, but with a few changes. Skin cells were taken
from the ear of a cow and placed into a nucleated egg cell;
the cell began to divide and eventually the embryo was transferred
into a surrogate cow and allowed to go to term. The difference
between this process and Dolly was that the cells used in the
cows were taken at the end of their natural life span, whereas
the cells that went on to create Dolly where starved and therefore
prevented from growing.
At
the time of Dolly it was thought that cells at the end of
their life span would not be able to go on to a full term
birth. The birth of the cloned cows proved this to be untrue
and in affect reversed the ageing process.
What
Is An Old Cell?
Almost
all cells contain inbuilt clocks
called
Telomeres. These are made from strips of DNA and are found at
the end of each chromosome. Their function is to keep the genetic
threads from fraying each time a cell divides. Without a way
of protecting themselves, the result is wear and tear and eventually
the telomeres get shorter and shorter, until they become so
short that the cell can no longer divide and eventually it dies.
Lanza explains what was found in the cloned cows,
'For the first time we are showing that cloning can take old
cells backwards in time and restore them to a youthful state.
This not only means that we could clone healthy cows from cells
at the end of their life span, but these animals appeared to
have cells that were much younger than their chronological age.
They have telomeres that are much longer than those for their
normal age, but they are also much longer than those of newborn
calves. Not only were their telomeres longer but in some cases
the cells themselves in some cases lived twice as long as normal.
On top of the longer lifespan these cloned animals have cells
that have three and half times the amount of ETC1 [an age dependant
gene which is expressed at very high levels in young early passage
cells]. This was suggesting that the animals were actually younger
than their biological age.'
How
Could This Happen?
If the scientists at ACT are honest they don't really understand
how this effect was achieved, but they have been able to replicate
it and grow large numbers of rejuvenated cells. Lanza gives
his theory for what has happened,
Lanza
gives his theory for what has happened,
'I think the answer lies in the donor cells. There could
be something going on in cells that have lived longer, so that
cloned cells with a longer lifespan, lead to animals with a
longer lifespan. We don't full understand the ageing process,
and there could be some overcompensation because these cells
had extremely short telomeres.'
Uses
And Benefits Of The Research
At this stage researchers do not know if the animals themselves
will live longer and consequently have an impact on milk yields.
They could, in Lanza's words, be 'the longest living cows
on the planet.' But, their creation could have far wider
implications in terms of therapeutic cloning and the ability
to grow replacement human organs. Lanza explains,
'The
fact that we can reverse the ageing process and generate healthy
cells could be used to treat a long list of human diseases caused
by tissue loss and dysfunction including heart disease, diabetes
and Parkinsons Disease. For instance if you had a damaged heart
we could take a few cells from you, grow up new heart cells,
which would be your own cells so your body wouldn't reject them.
What could be possible would be to create what is called a myocardial
patch so that you could fix the damaged heart. Before now there
was no way to generate enough cells to create the patch. What
this research shows is that the life span of cloned cells is
much longer than normal, the extended life span could lead to
a billion fold, or even a trillion fold, increase in the number
of replacement cells that could be used for tissue engineering
and transplantation therapies.'
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| 'They
could, in Lanza's words, be "the longest
living cows on the planet".'
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Future
The ramifications of this research for humans are wide ranging
and whilst the scientist may not have all the answers yet, they
can think ahead to what maybe. Lanza comments,
'A child may be able to live to over 200 years, people may not
develop chronic disease of old age until they are 150 years
old, the immune system of an adult may be akin to that of a
teenager and who knows childbearing age may be extended to 60
or even 80 years old. It's speculation at this point, we are
going to have to wait and watch these animals very carefully.'
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| Dr
Robert Lanza can be heard on Science In Action.
Find this on our interactive
radio... |
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| A
Cow Called... |
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| The
cloned calves are called Persephone, Lily, Daffodil,
Crocus, Forsythia and Rose. |
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| Hello
Dolly |
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| Dolly
the sheep was named after country singer Dolly Parton,
because she started life as a mammary cell. |
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Listen
to the whole interview
