hayflick numbers

MFossel mfossel at aol.com
Sun Jul 28 11:49:50 EST 1996


Luke:

No, the number is NOT always 50 +/- 10.  It depends on the species, cell
type, and age of the individual from which the cells were drawn.  The
extreme example would be HeLa cells (an ovarian cancer cell line from a
woman named Helen Lake) which have an (apparently) infinite Hayflick
number.  On the other hand, the Hayflick number of normal fibroblasts
drawn from children with progeria is markedly decreased (but highly
variable between children).

When cells approach their Hayflick limits a number of things happen.  The
cell's division rate slows and it finally stops dividing.  Equally as
important, its pattern of gene expression changes ("senescent gene
expression") to the point that the cell no longer maintains normal
homeostatic defences and no longer functions appropriately in supporting
other neighboring cells.  For further details, you might try my book
(borrow it and save $25 dollars).

Best wishes, 
Michael Fossel, MD, PhD
Author, Reversing Human Aging




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