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- Scientists have achieved a medical first by reversing
the ageing process in animal cells. Six cloned calves have been born with
cells appearing younger than a normal animal and they could live for 50
per cent longer.
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- Cloned: five cows that could live for 50 percent longer
after their cells' 'clock' was turned back by scientists.
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- The benefit for humans is that cloning could be used
to create youthful tissue from elderly patients to treat degenerative diseases
such as Parkinson's, Alzheimer's and diabetes, as well as heart, liver
and kidney conditions.
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- Scientists still do not fully understand why the ageing
process was reversed. Dr Michael West of Advanced Cell Technology (ACT)
the American company which made the breakthrough, said: "We can run
biology in reverse."
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- He said the cellular clock in the aged cells used to
clone the calves had been wound back beyond the embryonic state so they
live longer than normal. A cell's life ends when it can no longer divide.
Cells from a normal new-born calf divide 60 times in the laboratory. Cells
from the clones divide 90 times, so the calves could live up to 50 per
cent longer, to an age of 30.
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- But because ageing takes place at the level of the organism
as well as the cell, Dr West will have to wait decades to see if these
calves really do live longer than normal. He doubts the method could rejuvenate
a human although he accepts that, combined with genetic modification, it
could lead to tinkering with the rate of ageing of a cloned embryo.
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- If the results could be transferred to humans, and if
the rate of cell ageing is reflected by the entire organism, then humans
cloned in a similar way could live up to 200 years. Dr West said the advance
will have an immediate impact on efforts to create "young" tissue
to treat the diseases of old age, for instance by recreating the bone marrow
of a cancer patient.
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- He said: "With this research we have shown that
it may eventually be possible to improve the quality of life for millions
of people. In addition to patients with heart, liver, and kidney disease,
over 16 million patients worldwide suffer from neuro-degenerative disorders
such as Parkinson's and Alzheimer's disease. Millions more suffer from
diabetes and other diseases that may one day be treatable using these new
technologies."
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- The researchers describe how they rewound the ageing
clock in cells in the journal Science. The clock consists of a strand of
DNA on the end of all chromosomes called telomeres. Every time a cell divides
they become shorter. The ageing clock is eventually run down when the cells
stop dividing.
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- The results of previous research indicated that even
cloned cells retained the ageing clock of the clone donor. For example,
the technique used to clone Dolly the sheep turned back time in one sense,
converting an adult cell into an embryonic cell. But it did not reset the
cellular ageing clock, so that her telomeres were shorter than for a normal
newborn.
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- Today's report describes the cloning of six calves generated
from cells at the end of their lifespan, after 1,900 attempts. The calves
suffered the usual problems of cloning, being large at birth and suffering
breathing problems and high blood pressure.
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- But they were normal at two months, except for their
telomeres. Dr Robert Lanza of ACT, first author of the report, said: "The
old cells were not merely returned to a youthful state. They were actually
given a longer life span than those from normal animals." The team
suspects rejuvenation is linked to the type of cell used, a skin cell called
a fibroblast, rather than the mammary cells used for Dolly.
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- If the feat can be routinely accomplished it will be
possible to regenerate and rejuvenate cells and tissues for the repair
of age-related disease. The cloned animals, one of which celebrates its
first birthday this week, have telomeres that look like newborn calves
although they were cloned from senescent cells.
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- The company aims to create human stem cells - the basic
cells that form all the cells in the body. These cells would then be capable
of differentiating into a variety of human cells, such as heart cells,
neurons, blood cells or islets for transplant therapies. By showing the
cellular clocks of these stem cells can be reset, ACT has shown that human
therapeutic cloning may give scientists the potential to grow young cells,
tissues, and organs for an ageing population.
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- Therapeutic cloning is controversial because it requires
creating a human embryo and harvesting stem cells, which would destroy
it. The Nuffield Council on Bioethics says the potential benefits outweigh
ethical concerns and a committee is expected to approve research.
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- Interview with Dr. West on anti-aging cloning breakthrough:
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- http://www.lef.org/featured-articles/apr2000_clon_01.html
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