Researchers
Jump-Start Nerve Fibers to Significantly Reverse Stroke Damage
Dramatic results
of anti-Nogo therapy in rats that had medically induced strokes:
findings "of great clinical importance
Dec. 7, 2010 - A
new technique that jump-starts the growth of nerve fibers could reverse
much of the damage caused by strokes, researchers report in the Jan. 7,
2011, issue of the journal Stroke.
"This therapy
may be used to restore function even when it's given long after ischemic
brain damage has occurred," senior author Gwendolyn Kartje, MD, PhD, and
colleagues write.
The article has
been published online in advance of the print edition.
Kartje is
director of the Neuroscience Institute of Loyola University Chicago
Stritch School of Medicine and chief of neuroscience research at Edward
Hines Jr. VA Hospital.
Currently
doctors can do little to limit stroke damage after the first day
following a stroke. Most strokes are ischemic (caused by blood clots). A
drug called tPA can limit damage but must be given within the first
three hours for the greatest benefit -- and most patients do not receive
treatment within that time frame.
Kartje and
colleagues report on a treatment called anti-Nogo-A therapy. Nogo-A is a
protein that inhibits the growth of nerve fibers called axons. It serves
as a check on runaway nerve growth that could cause a patient to be
overly sensitive to pain, or to experience involuntary movements. (The
protein is called Nogo because it in effect says "No go" to axons.)
In anti-Nogo
therapy, an antibody disables the Nogo protein. This allows the growth
of axons in the stroke-affected side of the body and the restoration of
functions lost due to stroke.
Kartje and
colleagues report dramatic results of anti-Nogo therapy in rats that had
experienced medically induced strokes. Researchers trained rats to reach
and grab food pellets with their front paws. One week after experiencing
a stroke, the animals all had significant deficits in grabbing pellets
with their stroke-impaired limbs. There was little improvement over the
next eight weeks.
Nine weeks after
their stroke, six rats received anti-Nogo therapy, four rats received a
control treatment consisting of an inactive antibody and five rats
received no treatment.
Nine weeks
later, rats that had received anti-Nogo therapy regained 78 percent of
their ability to grab pellets.
By comparison,
rats receiving no treatment regained 47 percent of that ability, and
rats receiving the control treatment of inactive antibodies regained 33
percent of their pre-stroke performance.
Subsequent
examination of brain tissue found that the rats that received anti-Nogo
therapy experienced significant sprouting of axons.
Researchers
wrote that anti-Nogo-A therapy "can induce remarkable compensatory
sprouting and fiber growth, indicating the responsiveness of the
chronically injured brain to form new neural networks under the proper
growth conditions."
The findings
"are of great clinical importance," researchers concluded. Anti-Nogo-A
therapy "may benefit not only victims of spinal-cord injury or patients
in the early stage of stroke recovery, but also patients in later stages
who suffer from neurological disability due to brain damage from stroke
or other causes."
In a Phase I
trial including other centers, patients paralyzed by spinal-cord
injuries are receiving anti-Nogo therapy. The trial is sponsored by the
pharmaceutical company Novartis.
Kartje's study
co-authors are first author Shih-Yen Tsai, MD, PhD, and Catherine
Papadopoulos, PhD, of Hines VA Hospital and Martin Schwab, PhD, of the
University of Zurich.
The study was
funded by the Department of Veterans Affairs and the National Institute
of Neurological Disorders and Stroke.
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Dec. 7, 2010 - A
new technique that jump-starts the growth of nerve fibers could reverse
much of the damage caused by strokes, researchers report in the Jan. 7,
2011, issue of the journal Stroke.
In a Phase I
trial including other centers, patients paralyzed by spinal-cord
injuries are receiving anti-Nogo therapy. The trial is sponsored by the
pharmaceutical company Novartis.