Telomeric Theory of Aging II
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Sun Aug 23 23:06:56 EST 1998
C) Telomeres and Organismic Aging
This is probably the least studied aspect of the telomeric theory of aging.
Much of the following are conjectures and hypothesises suggested from the
research to date. Future research, (some of which are presented in the
discussion section), will help clarify the role that telomeres play in
It is possible that telomeric length itself is the single determining factor
in organismic life span but it is highly improbable. More likely it is a
major factor effecting the longevity of replicating cellular systems and a
contributor, primarily via the aging of the vascular system, to the decline
in functioning of non-reproducing cells.
Assuming an organism has avoided all prior causes of organismic death its
life span is still limited by aging itself. This organismic death manifests
itself through failure(s) in some vital bodily system but is directly related
to the body not being able to maintain or replace the cells making up these
Since the loss of telomeric length on the chromosomes is the limiting factor
in cell replication, (in dividing cellular systems), it is logical to assume
that this is the underlying cause of cellular loss and thus subsequent
failure of these vital systems.
If a methods are developed to maintain or enhance telomeric length we may be
able to not only stop the failure of these vital systems but if cellular mass
can also be replaced we might be able to restore maximum functioning in these
system and "rejuvenate" the system.
Several related problems would need to be resolved for this "therapy" to be
effective. First, the rate of mitotic division to restore lost cellular mass
must be increased. Merely restoring the replicative capacity of the cells,
by adding telomeric length, may not be sufficient to actually cause the cells
to divide to restore the functions of these systems. It is possible that the
normally present chemical progenitors of cellular reproduction would initiate
the process but in their absence the use of various growth factors may be
required, (more on growth factors under Related Research).
Secondly, the problems involving age related genetic expression need to be
addressed. Once again, replacing lost cellular mass may not be sufficient to
assure the appropriate genes necessary to the functioning of the system are
expressed when and where they are needed. Some research into the causes and
failures of genetic expression are currently being conducted and telomeric
length itself may play a role in controlling genetic expression but much
further research is required in this area.
Finally and most troubling are the problems related to aging and death of
non-reproducing cells, most notably nerve and muscle cells. Extending
telomeric length would have no direct impact on the aging of these cellular
systems. There is the possibility that if the vascular and immune systems of
the body were restored through telomeric lengthening then there could be a
beneficial effect on these non-dividing cells. It is believed that other
than oxygen or sugar deprivation or an inability to rid itself of waste
products, there is no reason for a nerve cell to die.
Other non-dividing cells may be subject to mitochondrial aging related to
oxidative stress and alternative strategies may be required to address these
problems, (see more under Related Research).
This is just a brief overview of how the telomeric theory of aging is
possibly involved in the process of organismic aging but the picture will
become much clearer and perhaps need to be revised as the research results
(Next: Background of the Theory)
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