http://www.sciam.com/news/110600/3.html
September 4, 2001
Stem
cells injected into the spinal fluid of newly paralyzed mice and rats
can restore movement, according to a study described yesterday in New Orleans
at the annual meeting of the Society for
Neuroscience. Unlike most stem
cell research, which has focused on repairing damage to small areas
of the central nervous system (such as injuries caused by a stroke), this
study is among the first to demonstrate the efficacy of stem cell treatment
in restoring function over a large region of the central nervous system.
Researchers say the new findings may lead to better treatments for human
patients afflicted with motor neuron diseases such as amyotrophic lateral
sclerosis (ALS) and spinal motor atrophy (SMA), which ultimately lead to
paralysis and death.
Investigators led by neurologist
Douglas Kerr
of Johns Hopkins University injected neural stem cells (like those shown
in the photograph) into the cerebrospinal fluid of 18 rodents infected
with the Sindbis virus, which normally leads to permanent paralysis. Several
weeks later the cells had migrated from the injection site at the based
of the spinal cord up to the so-called ventral horn, a region that contains
the bodies of motor nerve cells. "After eight weeks we saw definite functional
improvement in half of the mice and rats," Kerr reports. "From 5 to 7 percent
of the stem cells that migrated to the spinal cord appeared to differentiate
into nerve cells."
Exactly how so few nerve cells can
confer this considerable improvement in function is a question the team
is working to explain. "It could be that fewer nerve cells are needed for
function than we suspect," Kerr surmises. "The other explanation is that
the stem cells themselves haven’t restored the nerve-cell-to-muscle units
required for movement but that, instead, they protect or stimulate the
few undamaged nerve cells that still remain." Whatever the answer, the
results do offer hope. "Under the best research circumstances," says team
member Jeffrey
Rothstein, "stem cells could be used in early clinical trials within
two years."
Kate Wong