Three
Giant Steps for Stem Cells
Specific
genes have been identified that have the ability to develop into any
of the 200.000 cells in the body.
The controversial field
of stem cell research got boosts from several directions this week,
with three breakthrough studies published and a company announcing
another new development.
All of the work puts
stem cell researchers one step closer to using the cells to treat
people with diabetes, Alzheimer's disease, spinal cord injuries and
various other problems that are caused by irreparably damaged cells.
Genes give stem cells
magic: For the first time, Princeton University researchers have
identified specific genes that give stem cells their unique ability to
develop into any of the 200,000 cells in the human body.
The researchers
identified 283 genes common to many important types of stem cells, in
research published in the Sept. 12 issue of Science.
In another study,
published in the Sept. 11 issue of the Proceedings of the
National Academies of Science, the same researchers identified
about 4,000 genes that are active in the surrounding tissues that
nurture stem cells and give them cues about how to behave. The
researchers have published databases of the genes online and are free
for anyone to access.
Stem cells take their
cues from within as well as from surrounding cells, they said, and by
looking at both, researchers will be better able to coax the cells
into becoming heart, lung, brain or other types of cells.
"That is why we
think these papers are so complementary," said Ihor Lemischka, an
author on the Science paper, in a statement. "They
form the Princeton group's philosophy for how to proceed in stem cell
biology. You have to do it simultaneously from the point of view of
the stem cell and point of view of the micro-environment in which the
stem cell resides."
The unbearable
stemness of being: In other research also published in Science,
scientists came up with more questions than answers about the genes
that are common to stem cells.
They found that many of
the same genes are found in all kinds of stem cells (from embryos or
from adult blood, bone marrow or brains) -- but a large number of them
have not been sequenced and their function has not been determined.
A brand new brain:
ReNeuron Holdings, Europe's first listed stem cell company, says it
has solved a sticky problem in its stem cell technology and expects to
begin human trials in 2004.
That's already three
years later than they'd originally hoped. They'd hoped to treat
patients with Parkinson's disease and stroke by injecting fetal stem
cells into patients' brains, but found that the stem cells became
genetically unstable after being replicated many times.
A
guinea pig's guinea pig: Johns Hopkins scientists have made a
pacemaker out of a guinea pig.
The researchers say it's
the first pacemaker made of biological materials. They used gene
therapy to convert part of the guinea pigs' heart muscle cells into
"pacing" cells.
"We now can
envision a day when it will be possible to recreate an individual's
pacemaker cells or develop hybrid pacemakers -- part electronic and
part biologic. It
will be several years before the pacemaker is used in the clinic.
Guinea pig heart cells
spontaneously and rhythmically "fired" after the scientists
genetically altered the level of potassium in the tissue.
The biological pacemaker
could be a good option for patients who can't have electronic
pacemakers implanted because of the risk of infection, or for patients
who are too small to accommodate one.
This
is akin to turning a clunky old car into a hot rod -- if you have the
parts and expertise, it can be done.
