Transcript Adult stem cells: Short & long

Different cells have different talents
But - all
came from
one
How do cells
differentiate?
Some cell types
continue to replace
Other cell types slow down or stop
replacing
If an organ malfunctions, we might
replace it, but….
Brain & spinal
cord: no
regrowth, no
transplant
Defects in
development
when cell
differentiation
goes wrong
Cancer is cell differentiation
gone wrong
How do cells
differentiate?
Original cell
has a
complete set
of DNA
directions
Every differentiated cell has all the DNA directions
…but they’re stuck.
All the genes are there, but only a
few are switched on.
Control this, you control differentiation..but how?
Microarray technology detects switched-on genes
All the genes are there, but only a
few are switched on.
Control this, you control differentiation!
Bone marrow the first known “stem cells” they’re multipotent
Early
embryos have
pluripotent
cells
Very earliest
embryo cells
are
TOTIPOTENT
Nov 1998:
Stem cells
Grown from
Human embryos
John Gearhart, Hopkins
Scientists’ Benefit: replacement of diseased tissues
Public’s Concern: sacrifice of embryos
Nov 2000
Adult stem cells produce
neurons, heart cells,etc.
QuickTime™ and a
GIF decompressor
are needed to see this picture.
Q. Decision-makers:Can’t we use adult stem
cells instead of embryos?
A. Most scientists say “we need both!”
Mar 2001
Scientists repair damage from heart
attack using adult bone marrow stem cells
x
Aug 2001:
Bush approves limited
Embryonic lines
2004
Some of the promise of adult stem cells
Not panning out
x
2004
Exciting research
gone elsewhere
January 2005: All cell lines
contaminated
Nonhuman
Sialic acid
Neu5Gc
Feb 2005
Caveat: stem cell side effects
the case of the sensitive rats
Science has a long way to go