From: Robert J. Bradbury (bradbury@aeiveos.com)
Date: Sun Dec 15 2002 - 06:11:36 MST
Joao,
Re:
> True, but as a lot of research has shown recently, neurons can be
> replenished under special circumstances--e.g. spinal cord damage. Even
> cardiac muscle can be repaired if damage occurs and heart cells can
> replicate. Please see:
I'm generally aware of the neuronal work (though I haven't read the specific
papers you cite). I think there is a lot of potential with respect
to the repair of motor neurons -- with regard to cognitive functional
areas I'm less optimistic (this may involve key developmental gene
expression and brain functional organization processes).
Regarding myoblast repair, I'm more well informed. Aeiveos Sciences
Group was one of the first organizations to culture avian myoblasts
in order to investigate avian oxidative stress resistance (this was
in 1996-7 though the work was never published).
So yes, in general I agree that stem cell abilities can compensate
for some, perhaps many of the declines that occur with aging. But
I would argue that they are not a universal solution. Mammals simply
do not have genomic programs that have the organ (or at least limb)
regrowth properties of the genomic programs of lizards, lobsters, etc.
But I would argue that other, perhaps older, genomic programs
may have solved some of the problems of organ renewal to a
better extent than the mammalian program has. In mammals
it only seems to be really effective in the liver and in
the blood cells (to some extent). That leaves a lot of other
organ systems that can fail and cause a "premature" death.
Whether or not those programs have been developed in various
species, there is no reason to believe that one could not
select a relatively "perfect" genome and regenerate an organ
within an individual. Sequoia trees manage to do it for
three or four thousand years.
Robert
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