- Scientists have created "miracle mice" that
can regenerate amputated limbs or damaged vital organs, making them able
to recover from injuries that would kill or permanently disable normal
animals.
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- The experimental animals are unique among mammals in
their ability to regrow their heart, toes, joints and tail.
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- And when cells from the test mouse are injected into
ordinary mice, they too acquire the ability to regenerate, the US-based
researchers say.
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- Their discoveries raise the prospect that humans could
one day be given the ability to regenerate lost or damaged organs, opening
up a new era in medicine.
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- Details of the research will be presented next week at
a scientific conference on ageing titled Strategies for Engineered Negligible
Senescence, at Cambridge University in Britain.
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- The research leader, Ellen Heber-Katz, professor of immunology
at the Wistar Institute, a US biomedical research centre, said the ability
of the mice at her laboratory to regenerate organs appeared to be controlled
by about a dozen genes.
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- Professor Heber-Katz says she is still researching the
genes' exact functions, but it seems almost certain humans have comparable
genes.
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- "We have experimented with amputating or damaging
several different organs, such as the heart, toes, tail and ears, and just
watched them regrow," she said.
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- "It is quite remarkable. The only organ that did
not grow back was the brain.
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- "When we injected fetal liver cells taken from those
animals into ordinary mice, they too gained the power of regeneration.
We found this persisted even six months after the injection."
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- Professor Heber-Katz made her discovery when she noticed
the identification holes that scientists punch in the ears of experimental
mice healed without any signs of scarring in the animals at her laboratory.
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- The self-healing mice, from a strain known as MRL, were
then subjected to a series of surgical procedures. In one case the mice
had their toes amputated -- but the digits grew back, complete with joints.
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- In another test some of the tail was cut off, and this
also regenerated. Then the researchers used a cryoprobe to freeze parts
of the animals' hearts, and watched them grow back again. A similar phenomenon
was observed when the optic nerve was severed and the liver partially destroyed.
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- The researchers believe the same genes could confer greater
longevity and are measuring their animals' survival rate. However, the
mice are only 18 months old, and the normal lifespan is two years so it
is too early to reach firm conclusions.
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- Scientists have long known that less complex creatures
have an impressive ability to regenerate. Many fish and amphibians can
regrow internal organs or even whole limbs.
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