Cells and Aging

Thomas Mahoney excelife at earthlink.net
Fri Mar 12 02:35:56 EST 1999

In article <36E8B74E.5C75DEB3 at ryley.com>, james at ryley.com says...
>Robert Ames wrote:
>> In article <36E71F6F.EE8E824A at ryley.com>, James <james at ryley.com> wrote:
>> >effect.  The correlation says that satellite cells exhibit
>> >reduced replicative capacity when they have to divide over and
>> >over again -- whatever the cause (disease or old age).  That
>> >sounds reasonable enough.
>> >
>> >But the question is: So what?  Is it biologically relevant?  Can
>> >you provide me with any evidence at all that there is more than
>> >correlation at work here?  Any evidence that the AMOUNT of
>> >reduction in replicative capacity is sufficient to cause muscle
>> >wasting in old age?
>> There have been some gene transfer experiments recently in which the
>> MyoD gene is transduced into normal cells -- fibroblasts for example
>> -- thus converting them into muscle cell precursors.  This line of
>> research has the potential to provide evidence along the lines you're
>> seeking.  Eventually.
>Yes, I am familiar with that work, and though it wouldn't be
>perfect evidence, it would be nice to know if you could inject
>myoD-transformed cells into muscle, and have them replenish the
>muscle in old age.

Now you're getting close!  But why doesn't this procedure nor the 
introduction of IGF-1 restore full musculature in elderly mice?

Is it possible that both the myoD-transformed cells and the IGF-1 enhanced 
cells have reached their full replicative capacity before they can replace 
total musculature?  And lacking these procedures, isn't it likely that the 
satellite cells would have reached that stage earlier?

Thomas Mahoney, Pres.
Lifeline Laboratories, Inc.

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