X-Message-Number: 10507
Date: Thu, 01 Oct 1998 19:02:40 -0400
From: Jan Coetzee <>
Subject: Tissue regeneration by mice

Tissue regeneration linked to genes

NEW YORK, Sep 30 (Reuters) -- A group of researchers say they are close
to identifying a
group of genes linked to complex tissue regeneration in mice. They
believe their findings could
further research into human organ and limb regeneration after trauma or
illness.

After injury, wound healing in mammals usually involves repair through
cell proliferation rather
than regeneration, which involves replacement of damaged tissues.
Mammals usually cannot
regenerate complex body structures, which can result in loss of
function. However, scientists at
the Wistar Institute in Philadelphia, Pennsylvania, say they have now
identified a strain of mice
that ``undergo rapid and complete wound closure that resembles
regeneration.'' Their report is
published this week in the Proceedings of the National Academy of
Sciences.

``What is remarkable,'' they say, is that these wound closures ``not
only display full healing but
also show the recovery of normal architecture,'' including the regrowth
of skin, cartilage, blood
vessel, hair follicles, and sebaceous glands -- all without scarring.

After discovering that the ``MRL/MpJ'' strain of mice was able to effect
an apparent regeneration
of damaged ear tissue, the authors examined the mouse's genome (genetic
'blueprint') to seek out
genes associated with this process. The discovery of a mouse capable of
regeneration is
particularly important, the scientists say, since the genetic code of
mice is both well-understood
and similar to that of humans.

The researchers say they have identified various areas of the mouse
genome thought to be home
to ``at least five unlinked (mouse) genes that can contribute to (this)
healing.''

They report that one of the suspect genes is located in a chromosomal
region similar to that
responsible for regeneration in amphibians -- many species of which are
capable of regrowing
whole limbs. Another gene has been linked to the production of retinoic
acid, a protein involved
in mammalian tissue development and the growth of skin.

In an interview with Reuters Health, Dr. Giovanni Rovera, director of
the Wistar Institute,
explained that the final identification of these genes will be only the
beginning of regeneration
research. ``We understand so little,'' he said, ''but I think we are one
step closer.''

He believes the next logical step would be an exact identification of
the genes themselves. At the
present time, he said, all we have determined is an 'address' for the
genes. ``I would compare it
to saying 'this is the town where these genes live,''' he explained.

Of course, the 'holy grail' of this type of research would be the
development of a medical means
of allowing humans to regrow limbs, organs, or damaged spinal cords.
However, Rovera
cautioned that experts ``suspect that regeneration of an organ or a limb
is controlled by many
elements, of which these genes are only representing one of those many
elements.''

SOURCE: Proceedings of the National Academy of Sciences
1998;95:11792-11797.

I think this is not only important for cryonics but aging as well
because in salamanders regenerated tissue appear to be "young".

J.C.

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