Brian (digibri) wrote,



It's a miracle: mice regrow hearts

August 29, 2005
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.

The experimental animals are unique among mammals in their ability to
regrow their heart, toes, joints and tail.

And when cells from the test mouse are injected into ordinary mice, they
too acquire the ability to regenerate, the US-based researchers say.

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.

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.

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.

Professor Heber-Katz says she is still researching the genes' exact
functions, but it seems almost certain humans have comparable genes.

"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.

"It is quite remarkable. The only organ that did not grow back was the

"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."

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

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.

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

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.

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.

The Sunday Times
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