FROM:
 Sign On San Diego.com
http://www.signonsandiego.com/news/science/20041025-9999-1m25stem.html

Scientists discuss uses, potential of stem cells
Tissue-regeneration progress reported
By Bruce Lieberman
UNION-TRIBUNE STAFF WRITER
October 25, 2004

Injured spinal cords, Parkinson's disease and brain tumors – all are
targets for the regenerative power of stem cells, neuroscientists said
yesterday.

The researchers, joining 30,000 of their colleagues in San Diego this
week for the largest annual meeting of neuroscientists in the world,
spoke of the latest studies to manipulate stem cells to help restore
health.

The scientists discussed potential approaches using both embryonic stem
cells, which can develop into every other cell in the body, and adult
stem cells, the storehouse of replacement cells identified in several
tissues and organs.

The briefing yesterday came a little more than a week before California
voters determine the fate of Proposition 71, an initiative that would
raise $3 billion in state bond proceeds to fund research grants.

President Bush has restricted funding to a small number of stem cell
lineages available as of Aug. 9, 2001, saying the destruction of further
embryos would be tantamount to killing human lives. Scientists argue that
they need access to new embryos, many of them discarded each year by
fertility clinics, to study their full potential.

Yesterday, a handful of researchers at the Society for Neuroscience
meeting spoke about areas that show the potential power of stem cells to
fight injury and disease.

Hans Keirstead from UC Irvine reported that his lab was able to coax
human embryonic stem cells into developing into oligodendrocytes, a type
of cell in the brain that forms myelin, a fatty substance that insulates
the long, wire-like extensions of nerve cells, called axons. The myelin
sheaths, which are also destroyed in people suffering from multiple
sclerosis, allow electrical signals to travel between nerve cells in the
brain and body.

After much effort to purify oligodendrocytes in the lab, Keirstead
transplanted the cells into rats seven days after their spinal cords had
been surgically severed.

The transplanted oligodendrocytes survived, migrated to the proper place
in the animals' damaged nervous system and restored myelin to the axons
that had lost it after injury, Keirstead said.

As a result, the animals were able to support their weight, re-animate
their tails and gain some walking ability.

"It's not perfect," said Keirstead. "They're not playing soccer, but
they're doing extremely well."

In other work, University of Wisconsin researcher Clive N. Svendsen
reported that neural stem cells taken from fetal tissue can be quickly
multiplied in the lab. The cells, then engineered to produce a
naturally-occurring molecule called a growth factor, glial-derived
neurotrophic factor or GDNF, were transplanted directly into the brains
of rats.

Once inside the brain, the stem cells producing GDNF led to increased
levels of dopamine, a key neurotransmitter lost in Parkinson's.

The federal government wants to make sure that researchers can control
the release of GDNF in the brain. If they can, then clinical trials could
begin in coming years, he said.

Evan Snyder, a stem cell biologist at The Burnham Institute in La Jolla,
said he is studying how stem cells transplanted into the brain appear to
attack tumors there.

In mice studies, Snyder has found that neural stem cells grown in the lab
and transplanted into mice migrated from one side of the brain to the
other, homing in on, surrounding and infiltrating tumors. They even
attack the blood vessels that feed them, he said.

Exactly why, or how, the stem cells find and attack brain tumors is
uncertain, but Snyder said the cells could be genetically engineered to
express proteins lethal to tumor cells.

"I have a lot of confidence that this will have an impact," Snyder said
of his preliminary work with animals.

"It's not a cure, but I think it could extend life."

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