X-Message-Number: 27866
Date: Sun, 23 Apr 2006 19:21:39 -0700 (PDT)
From: Doug Skrecky <>
Subject: replicative capacity and longevity

[The replicative capacity of non-stem cell populations may have little
impact on maximum lifespan. As long as the stem cell niche is maintained
the replicative capacity of other cell types may not be critical, since
they can, in the last resort be replenished by differentiating stem
cells. Aging of the stem cell niche might be a critical factor in
mammalian aging.]

Mech Ageing Dev. 2005 Oct;126(10):1130-3.
Cellular replicative capacity correlates primarily with species body mass
not longevity.
  Although the limited replicative capacity of human fibroblasts in
culture is frequently used as a model for aging, a question of major
interest is whether the relationship between in vitro fibroblast
proliferative capacity and species longevity is primary or secondary to a
relationship with species body size. In this report we establish that body
mass is the primary correlative of proliferative potential rather than
species life-span.

Also from the above paper:

                 Maximum       Maximum
Species          Longevity     Cell Doublings
naked mole rat   28 years      16
norway rat        5            19
human            90+           40
cattle           20            74

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