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Thread: Plastic tube may help treat paralysis

  1. #1

    Plastic tube may help treat paralysis

    CHICAGO, August 28 - Canadian researchers have created a plastic tube that fits around the spinal cord and restores some movement in paralyzed rats, according to research presented at the 222nd national meeting of the American Chemical Society, the world's largest scientific society. The researchers say the work could lead to a new treatment for paralysis in humans.
    Rats whose spinal cords had been cut walked somewhat better eight weeks after a plastic tube filled with chemicals that promote nerve growth was implanted in their spine. "We know the rats improved. What we have to do now is figure out how significant the improvement is," said lead researcher Molly Shoichet, Ph.D., an associate professor at the University of Toronto. Shoichet, who has studied 80 rats to date, cautions that significantly more work needs to be done with animals before the treatment can be tested in people.

    On a common test of paralysis that is scored from 1 (complete paralysis) to 21 (normal movement), injured and untreated rats scored a 2. Those rats that were treated with the chemical-filled tube scored between 8 and 11, depending on the chemical used.

    The tube, made of the same material used for contact lenses and only 5 millimeters in length, fits snugly around the injured area and serves as a "bridge" that connects the damaged nerves. Designed to mimic the flexibility of the spinal cord, the tube provides a pathway along which neurons can grow.

    "We saw some directed nerve tissue growth along the plastic tube, but we do not yet know if the severed nerves were connected to the newly grown tissue," said Shoichet. "We hope that once axons grow across the gap they will make the appropriate connections."

    Unlike nerves in other parts of the body which regenerate rapidly after an injury, spinal cord nerves must be coaxed into growing. Other researchers are testing the practicality of using injections or genetically-modified cells to deliver growth factors to the injured neurons, but Shoichet's group is the first to use a chemical-filled tube that matches the properties of the spinal cord itself.

    There are few effective treatments for spinal cord injuries. In the 1940s, most injuries were fatal. Today, improvements in emergency medicine mean more people survive the initial injury, and most naturally regain some function within six months, according to the National Institute of Neurological Diseases and Stroke (NINDS). Physical therapy helps to maintain flexibility and function of the muscles and joints, but most sufferers are still left with permanent, severe disabilities. NINDS estimates that 10,000 people suffer a spinal cord injury every year, and 200,000 are currently living with the injury.

    As recently as a decade ago, doctors' only option was to realign and then immobilize the spinal column. Methylprednisolone - the first and only drug proven to limit secondary damage to the nerves - was therefore revolutionary when it was approved in 1990. But there is still no standard treatment to reverse the damage.

  2. #2
    Senior Member Jeff's Avatar
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    Jul 2001
    Argao, Cebu, Philippines


    This is one of those articles that impresses me with the number of things being worked that none of us were expecting. Can't wait until many of these helpful things are used in combination.

  3. #3
    Senior Member Jeremy's Avatar
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    Jul 2001

    More on the story

    Spine tissue discovery could help injury victims
    Tests show spinal cord can be regrown in rats
    Vanessa Lu

    BUILDING BRIDGES: Researcher Molly Shoichet speaks to scientists in Chicago yesterday.
    Researchers at the University of Toronto have managed to re-grow damaged nerve cells in paralyzed rats by implanting a chemical-filled plastic tube that serves as a bridge between two ends of a severed spinal cord.

    The results, presented yesterday at the American Chemical Society's meeting in Chicago, increase hopes that the research might eventually lead to a treatment for patients with spinal cord injuries.

    ``There's no magic bullet. This is not the answer yet, but it does provide some promise,'' says U of T researcher Molly Shoichet, cautioning much more research needs to be done before human trials would even begin. ``But I would definitely say there's hope.''

    Unlike damaged nerves in other parts of the human body, spinal cord cells cannot repair themselves or re-grow rapidly after an injury, which means patients are usually paralyzed for life.

    Using rats whose spinal cords had been cut, Shoichet, an associate professor in chemical engineering, found noticeable improvements in the rats' ability to walk eight weeks after plastic tubes were implanted.

    While the tubes did not result in a return to full mobility, the rats had increased use of their hind legs.

    The 6mm flexible tube, which Shoichet engineered to match the mechanical properties of the spinal cord, is made from the same material as contact lenses. Being 4mm in diameter, it fits snugly around the injured spinal cord and serves as a bridge to connect damaged nerves and provides a pathway for regeneration.

    To visualize the technique, imagine a cable of wires that is cut in half. Then take a straw, and place each end of the severed cable into either end of the straw with a 4-millimetre gap in between.

    ``We have seen nerve fibres growing within the tissue that is connecting both ends. We know that those nerves are from the spinal cord,'' said Shoichet during a telephone interview from Chicago yesterday. ``But we don't know if they go all the way back up to the brain.''

    The scientists used a paralysis scale from 1 to 21, with 1 representing complete paralysis and 21 representing normal movement. The injured and untreated rats scored a 2 rating. Rats that were treated with the chemical-filled tube scored between 8 and 11 depending on the type of chemical used.

    When Shoichet and a team of scientists first began this research, they used the plastic tube alone. They were surprised to discover nerve fibres developed.

    They then filled the tubes with different chemical proteins that stimulate cell regeneration. But they found no statistical differences among the proteins. Some rats responded better for no clear reasons.

    Future research on rats will focus on creating a lattice structure within the tube to direct specific cell regeneration from one end of the tube to the other. Researchers expect to add stem cells inside the plastic tubes to see if it can improve recovery rates.

    Research associate Paul Dalton, who works with Shoichet, added scientists do not know what is required for nerve regeneration in the spinal cord.

    ``Hopefully, we can sort out and understand what the spinal cord needs to regenerate itself,'' he said.

    Because Shoichet and Dalton are not neurologists, they are collaborating with neurosurgeon Dr. Eve Tsai, who works at Dr. Charles Tator's laboratory at the University Health Network's Toronto Western division.

    ``This may turn out to be a fruitful strategy in the future, but I wouldn't want to blow it out of proportion,'' Tator said yesterday. ``These rats showed some recovery of function, but it was very minimal.''

    He added that scientists don't know whether the plastic tube mimics a healthy spinal cord or if it creates a situation that encourages cell regeneration.

    ``Nerves are very choosy. They're very finicky,'' Tator said. ``Most times, when you cut nerves in the spinal cord, they just won't grow. . .. This seems to create a favourable environment in which the nerves, and their supporting cells, like to grow.''

    He attributed the growing research into spinal cord injuries in part because of high-profile advocates such as Toronto Star reporter Barbara Turnbull, actor Christopher Reeve and wheelchair athlete Rick Hansen.

    ``The science has created many avenues that look hopeful,'' Tator said. ``Fifteen years ago, there were one or two strategies that looked hopeful for spinal cord injuries. Today, there are at least a dozen strategies.''

    Other scientists are trying to regenerate nerves using stem cells or transplanting cells from other organs. Earlier this month, McMaster University researcher Michel Rathbone announced that spinal cord nerve cells in rats regenerated when cells from the rats' intestines were transplanted to the spinal area.

    For Canadians living with spinal cord injuries, ongoing research brings not only hope for a treatment someday but also better management of some symptoms such as bowel or bladder control and severe spasms.

    ``It's not all going to come together into a cure, but we certainly hope it would make activities in daily living easier,'' said Vince Miele, director of member services at the B.C. Paraplegic Association.

  4. #4
    Senior Member Max's Avatar
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    Jul 2001
    Montreal,Province of Quebec, CANADA

    Plastic Tube Helps Paralyzed Rats Regain Function

    Plastic Tube Helps Paralyzed Rats Regain Function
    By E. J. Mundell

    CHICAGO (Reuters Health) - A polymer tube inserted into the spinal columns of paralyzed rats seems to foster the regrowth of nerves, restoring some hind-leg function, Canadian researchers report. Although much more work needs to be done, they believe the device could prove to be a whole new way of treating spinal cord injuries in humans.

    ``We know the rats improved. What we have to do now is figure out how significant the improvement is,'' said Dr. Molly Shoichet of the University of Toronto. She presented her team's findings here Tuesday at the annual meeting of the American Chemical Society.

    In the US alone, more than 10,000 people suffer disabling spinal cord injuries each year, and more than 200,000 Americans now live with the often devastating consequences of such injuries. Although drug therapy can limit secondary damage to nerves following injury, there is currently no effective means of repairing or reversing damage to the spinal cord.

    However, Shoichet's team of chemical engineers speculated that nerve cells in the spinal cord might be induced to grow if provided with a nourishing, protective environment. Testing this theory, they developed a thin tube made of the same type of flexible water-permeable plastic found in contact lenses.

    The researchers inserted the tube, filled with hormones that encourage nerve growth, into the spinal columns of rats. The tube was placed in the 'gap' between the severed ends of the spinal cord.

    According to Shoichet, nerve cells inside the tubes soon began to send out long, spindly branches, called axons, indicating growth. Furthermore, treated rats--who had previously merely dragged their hind limbs behind them--appeared to regain at least some hind-leg function. On a standard functionality scale of 0-21 (with 21 being perfect function), the previously paraplegic rodents scored anywhere from 8 to 11--nowhere near full function, but still ``pretty amazing,'' Shoichet said.

    ``We're definitely not there yet,'' she told delegates, because although neurons are growing, they appear to need more ''guidance'' before they can close the gap to form a stronger, more reliable neural pathway.

    The Toronto team believes that that guidance might be provided by the insertion into the tube of a scaffold made up of tiny fibers. Axons could cling to the fibers as they grew, like vines curling round a fence.

    Laboratory experiments using just this type of scaffolding have been ``encouraging,'' Shoichet said, with neurons sending out axons to average lengths of over 12 millimeters.

    The next step, she said, is to implant scaffold-bearing tubes within paralyzed rats and then watch for signs of even greater improvement. ``We hope that once axons grow across the gap they will make the appropriate connections,'' she said.

  5. #5
    Senior Member rdf's Avatar
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    Jul 2001
    Someplace between Nowhere and Goodbye

    the times they are a changin'

    "Unlike nerves in other parts of the body which regenerate rapidly after an injury, spinal cord nerves must be coaxed into growing."

    Two years ago, maybe even one, you wouldn't have seen such a statement from a reporter. I'm glad that the fact that the spinal cord can regenerate is finally sinking in and being mainstreamed.

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