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Ed. Note: The following is a press
release from Johns Hopkins School of Medicine.
February 13, 2007 -- Human nerve stem cells transplanted into rats’
damaged spinal cords have survived, grown and in some cases connected with
the rats’ own spinal cord cells in a Johns Hopkins laboratory, overturning
the long-held notion that spinal cords won’t allow nerve repair.
A report on the experiments will be published online this week at PLoS
Medicine and “establishes a new doctrine for regenerative neuroscience,”
says Vassilis Koliatsos, M.D., associate professor of neuropathology at
Johns Hopkins. “The spinal cord, a part of the nervous system that is
thought of as incapable of repairing itself, can support the development of
transplanted cells,” he added.
“We don’t yet know whether the connections we’ve seen can transmit nerve
signals to the degree that a rat could be made to walk again,” says
Koliatsos, “We’re still in the proof of concept stage, but we’re making
progress and we’re encouraged.”
In their experiments, the scientists gave anesthetized rats a range of
spinal cord injuries to lesion or kill motor neurons or performed sham
surgeries. They varied experimental conditions to see if the presence or
absence of spinal cord lesions had an effect on the survival and maturation
of human stem cell grafts. Two weeks after lesion or sham surgery, they
injected human neural stem cells into the left side of each rat’s spinal
cord.
After six months, the team found more than three times the number of human
cells than they injected in the damaged cords, meaning the transplanted
cells not only survived but divided at least twice to form more cells.
Moreover, says Koliatsos, the cells not only grew in the area around the
original injection, but also migrated over a much larger spinal cord
territory.
Three months after injection, the researchers found evidence that some of
the transplanted cells developed into support cells rather than nerve cells,
while the majority became mature nerve cells. High-powered microscopic
examination showed that these nerve cells appear to have made contacts with
the rat’s own spinal cord cells.
The research was funded by the National Institute of Neurological Disorders
and Stroke, the Muscular Dystrophy Association and the Robert Packard Center
for ALS Research at Johns Hopkins.
Authors on the paper are Jun Yan, Leyan Xu, Annie M. Welsh, Glen Hatfield
and Koliatsos, all of Hopkins, and Thomas Hazel and Karl Johe of Neuralstem
of Rockville, Md.
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