In article <1992Apr27.105750.17252 at yang.earlham.edu>
allens at yang.earlham.edu (Allen Smith) writes:
>> If we're going to really stop aging, then we'll need to figure out
>how to get neurons to regenerate. Some clues can probably be found in the
>nasal neurons (which keep dividing); what's the current status of research
>on the cause of this difference?
I don't think we have to look as far as nasal neurons. In the 3/27/92
issue of Science, p 1707, BA Reynolds and S Weiss make a strong case for the
existance of neuronal stem cells which can differentiate into neurons and
astrocytes in adult mice when they are exposed to EGF. Since the receptors
for EGF are found in the human CNS this may be expected to work in humans
as well. They say, "Taken together, these findings suggest that a population
of embryonic stem cells may survive in the adult brain in a dormant,
nonproliferative state." I don't know if this has been discussed in the
neuroscience topic but I think this is hot stuff! The thing I find amazing
is that their data would indicate that these are 1.5% of the cell population.
Reflecting on this, it seems to me that there are stem cells in the bone marrow
which can regenerate our blood cells, stem-cell like hepatocytes which can
regenerate the liver, smooth muscle cells or perhaps stem-cells, that divide
and contribute to arteriosclerosis when stimulated with FGF and of course
precursor cells in the skin, intestine and uterus which undergo division
and differentiation to regenerate surface cells. All of this leads me to
conclude that there may be precursor cells left around for everything.
All they need is the right stimulation and voila, we have new tissue.