From: Robert J. Bradbury (bradbury@aeiveos.com)
Date: Fri May 30 2003 - 19:15:28 MDT
On Fri, 30 May 2003 matus@matus1976.com wrote:
> Why grow whole organs? Injecting a few stem cells into the offending organ
> will start replacing non-functional organ cells with correctly functioning
> ones.
Michael, these are valid points and I actually hope to see them
happen. I think you are correct and they may work in many of the
cases you cite.
The primary reason I bring up entire organs is because (a) there is a
history that transplants can be effective; and (b) there are probably many
cases where organs are a complex mixture of cell types (I'm particularly
concerned with the aging of the vasculature and that leading to stroke --
the vasculature is a complex mixture of cells with at least endothelial
cells and smooth muscle cells being involved.) I'm concerned that there
may be cases where stem calls cannot properly differentiate and regrow in
adult organisms -- e.g. development of the base system requires "stages"
e.g. a -> b -> c -> d but in the adult organism one only has "d".
Given some ~300 cell types I don't think we have scratched the
surface to know when stem cells will or will not function well
in adult organisms. Only when we have the complete "regulome"
of mammals and a reasonably good computer model for how this
regulates multicellular development may we begin to know if
simple stem cell therapy is going to solve most or all health
problems -- of course we can test all the possibilities but
I'd put my bets on having data from a computer model first.
Robert
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