Stem Cells May Repair Cord Damage
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http://news.yahoo.com/news?tmpl=story&u=/ap/20050920/ap_on_sc/stem_cells
Study: Stem Cells May Repair Cord Damage
By LAURAN NEERGAARD, AP Medical Writer
Mon Sep 19,10:26 PM ET
WASHINGTON - Injections of human stem cells seem to directly repair some
of the damage caused by spinal cord injury, according to research that
helped partially paralyzed mice walk again.
The experiment, reported Monday, isn't the first to show that stem cells
offer tantalizing hope for spinal cord injury — other scientists have
helped mice recover, too.
But the new work went an extra step, suggesting the connections that the
stem cells form to help bridge the damaged spinal cord are key to recovery.
Surprisingly, they didn't just form new nerve cells. They also formed
cells that create the biological insulation that nerve fibers need to
communicate. A number of neurological diseases, such as multiple
sclerosis, involve loss of that insulation, called myelin.
"The actual cells that we transplanted, the human cells, are the ones that
are making myelin," explained lead researcher Aileen Anderson of the
University of California, Irvine. "We're extremely excited about these
cells."
The research is reported in Monday's issue of Proceedings of the
National Academy of Sciences.
Stem cells are building blocks that turn into different types of tissue.
Embryonic stem cells in particular have made headlines recently, as
scientists attempt to harness them to regenerate damaged organs or other
body parts. They're essentially a blank slate, able to turn into any
tissue given the right biochemical instructions.
But they're not the only type of stem cell. Anderson and colleagues used
fetal neural stem cells, a type that are slightly more developed than
embryonic stem cells because they're destined to make cells for the
central nervous system.
The researchers injured the spinal cords of mice and nine days later
injected some with the human neural stem cells.
Four months later, the treated mice could again step normally with their
hind paws. Mice given no treatment or an injection with an unrelated cell
showed no improvement.
The question was what sparked that improvement. Injections of stem cells
might simply stimulate the body to produce some healing factor, or they
might directly repair damage themselves.
So Anderson injected the animals with diphtheria toxin, which kills only
human cells, not mouse cells. The improvements in walking disappeared,
suggesting it was the cells themselves responsible for recovery.
"It was striking," Anderson said.
Finally, the researchers analyzed the actual mouse spinal cords to see
what the human stem cells had turned into. The hope was that they would
make neurons, or nerve cells, and some did.
But the bulk of the injected stem cells formed oligodendrocytes, a
different type of cell that forms myelin, the insulation coating that is
key for nerve fibers to transmit the electrical signals they use to
communicate.
The toxin step was key to ensuring the transplanted cells themselves are
functioning, and all researchers must provide such evidence because
different types of stem cells almost certainly will work by different
mechanisms in different tissues, said Dr. Doug Kerr, a Johns Hopkins
University neurologist who is performing similar spinal cord research with
embryonic stem cells.
Much more research must be done before testing stem cells in people with
spinal cord injuries, cautioned Anderson. One question is how soon after
an injury cells must be administered to have any effect — no one knows how
nine days in a mouse's life correlates to the post-injury period for a
person. Also, the mice were bred to avoid immune system destruction of the
human cells, and suppressing a person's immune system because of similar
transplant rejection risk poses big problems.
"The last thing we want to do is take someone who's living a productive
life — if confined, we all understand that — and make them worse," said
Anderson, who said the work also shows the need to study all types of stem
cells. "The exciting part is the potential is there."
The research was funded by the nonprofit Christopher Reeve Foundation and
the
National Institutes of Health. StemCells Inc. of Palo Alto, Calif.,
provided the fetal-derived stem cells.
__
On the Net:
Proceedings of the National Academy of Sciences: http://www.pnas.org/
Copyright © 2005 The Associated Press. All rights reserved. The
information contained in the AP News report may not be published,
broadcast, rewritten or redistributed without the prior written authority
of The Associated Press.
Copyright © 2005 Yahoo! Inc. All rights reserved.
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http://news.yahoo.com/news?tmpl=story&u=/ap/20050920/ap_on_sc/stem_cells
Study: Stem Cells May Repair Cord Damage
By LAURAN NEERGAARD, AP Medical Writer
Mon Sep 19,10:26 PM ET
WASHINGTON - Injections of human stem cells seem to directly repair some
of the damage caused by spinal cord injury, according to research that
helped partially paralyzed mice walk again.
The experiment, reported Monday, isn't the first to show that stem cells
offer tantalizing hope for spinal cord injury — other scientists have
helped mice recover, too.
But the new work went an extra step, suggesting the connections that the
stem cells form to help bridge the damaged spinal cord are key to recovery.
Surprisingly, they didn't just form new nerve cells. They also formed
cells that create the biological insulation that nerve fibers need to
communicate. A number of neurological diseases, such as multiple
sclerosis, involve loss of that insulation, called myelin.
"The actual cells that we transplanted, the human cells, are the ones that
are making myelin," explained lead researcher Aileen Anderson of the
University of California, Irvine. "We're extremely excited about these
cells."
The research is reported in Monday's issue of Proceedings of the
National Academy of Sciences.
Stem cells are building blocks that turn into different types of tissue.
Embryonic stem cells in particular have made headlines recently, as
scientists attempt to harness them to regenerate damaged organs or other
body parts. They're essentially a blank slate, able to turn into any
tissue given the right biochemical instructions.
But they're not the only type of stem cell. Anderson and colleagues used
fetal neural stem cells, a type that are slightly more developed than
embryonic stem cells because they're destined to make cells for the
central nervous system.
The researchers injured the spinal cords of mice and nine days later
injected some with the human neural stem cells.
Four months later, the treated mice could again step normally with their
hind paws. Mice given no treatment or an injection with an unrelated cell
showed no improvement.
The question was what sparked that improvement. Injections of stem cells
might simply stimulate the body to produce some healing factor, or they
might directly repair damage themselves.
So Anderson injected the animals with diphtheria toxin, which kills only
human cells, not mouse cells. The improvements in walking disappeared,
suggesting it was the cells themselves responsible for recovery.
"It was striking," Anderson said.
Finally, the researchers analyzed the actual mouse spinal cords to see
what the human stem cells had turned into. The hope was that they would
make neurons, or nerve cells, and some did.
But the bulk of the injected stem cells formed oligodendrocytes, a
different type of cell that forms myelin, the insulation coating that is
key for nerve fibers to transmit the electrical signals they use to
communicate.
The toxin step was key to ensuring the transplanted cells themselves are
functioning, and all researchers must provide such evidence because
different types of stem cells almost certainly will work by different
mechanisms in different tissues, said Dr. Doug Kerr, a Johns Hopkins
University neurologist who is performing similar spinal cord research with
embryonic stem cells.
Much more research must be done before testing stem cells in people with
spinal cord injuries, cautioned Anderson. One question is how soon after
an injury cells must be administered to have any effect — no one knows how
nine days in a mouse's life correlates to the post-injury period for a
person. Also, the mice were bred to avoid immune system destruction of the
human cells, and suppressing a person's immune system because of similar
transplant rejection risk poses big problems.
"The last thing we want to do is take someone who's living a productive
life — if confined, we all understand that — and make them worse," said
Anderson, who said the work also shows the need to study all types of stem
cells. "The exciting part is the potential is there."
The research was funded by the nonprofit Christopher Reeve Foundation and
the
National Institutes of Health. StemCells Inc. of Palo Alto, Calif.,
provided the fetal-derived stem cells.
__
On the Net:
Proceedings of the National Academy of Sciences: http://www.pnas.org/
Copyright © 2005 The Associated Press. All rights reserved. The
information contained in the AP News report may not be published,
broadcast, rewritten or redistributed without the prior written authority
of The Associated Press.
Copyright © 2005 Yahoo! Inc. All rights reserved.
Questions or Comments
Privacy Policy -Terms of Service - Copyright/IP Policy - Ad Feedback
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