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Thread: Nerve Damage? Just Glue It!

  1. #1

    Nerve Damage? Just Glue It!

    I think this is an older (last year) article...But isn't this on the same line as what Dr. Cheng in Taiwan is doing/researching?
    Nerve Damage? Just Glue It!

    Peter Downs, Medical Writer






    If Richard Borgens is right, doctors someday may be able to simply glue damaged nerves back together so they work again.

    "We've actually proven that you can take strips of spinal cord and cut them in two and re-fuse them, and they work in minutes in animals. So, it is possible to reconnect totally severed nerve fibers," says Borgens, professor of developmental anatomy at Purdue and director of the Center for Paralysis Research.

    "This is certainly useful in peripheral nerve injuries," such as in arms or legs, says Jen Hill Lucas, assistant professor of physiology at Ohio State University. As for spinal cord injury, that "is a very tough nut to crack," she says. "I've learned to be very cautious, but this is a very innovative approach that appeals to me."

    "There is nothing else like this in all the various research people are doing on spinal cord injuries," says Andrew Blight, vice president of research and development at Acorda Therapeutics, a biotechnology company specializing in therapies for spinal cord injuries.

    So far, the most promising results have come from cell cultures and artificial injuries in guinea pigs. In an approach that more closely models real-life situations, Borgens' lab has started to treat dogs with spinal injuries, like those that have been struck by cars. Spinal cord injuries in dogs are very similar to those in humans, he says, but usually such wounded dogs are killed rather than treated. Borgens says he believes he can offer dog owners and their pets a humane alternative that will prolong the lives of the animals.


    How It Works


    In most spinal cord injuries, nerve fibers are squashed rather than cut. Immediately after the injury, there is nothing to re-fuse.

    Borgens' nerve glue is polyethylene glycol (PEG), a substance commonly used in medicine and cosmetics and generally regarded as safe. Cosmetics makers use it as an emulsifier.
    PEG appears to work in two ways: by fusing severed ends together and by sealing leaks in the nerve membrane.

    Borgens' crew applied PEG directly (they are looking at whether it will work as an injection) to severed nerves in the backs of guinea pigs to reconnect the nerves and restore function. Even the topical application, if it works in people, could be useful in treating severed nerves in a hand or leg, or even in the spine.

    In most spinal cord injuries, nerve fibers are squashed rather than cut. Immediately after the injury, there is nothing to re-fuse. As a result of changes started by bruising of the fibers and rupturing of cell membranes, nerves die and separate over a span of several days.

    The injured cells disintegrate because the chemical composition inside of the nerve cells becomes less and less different than the chemical makeup of the outside. When nerve cells communicate with each other, they do it by exploiting differences between different environments.

    When the cell membrane tears or leaks, ions concentrated inside the membrane flow out, and those concentrated on the outside flow in, depriving the nerve of the ability to transmit impulses. This eventually destroys the cell.

    PEG acts like a plug to stop the leaks, says Borgens. "It is like putting Stop Leak in your car's radiator," he says. "The PEG molecule inserts itself or covers holes or breaches in a nerve membrane. If you repair a membrane by sealing, you can rescue the nerve fiber [if] the damage hasn't gone on too long."

    Current common treatment after a spinal cord injury includes using a class of drugs called neuroprotectors. Their job is to prevent the total destruction of damaged nerve cells. The most widely used of these is methyprednisolone.

    Current neuroprotectors target specific ways that ions can cross the membrane, says Lucas, but "PEG is more general." It actually repairs leaks in cell membranes, adds Blight, while neuroprotectors merely stop damaged membranes from getting worse.


    Rapid Recovery


    One major question that has to be answered is whether PEG can be used with the standard neuroprotectors.

    Even in animals, the effect of neuroprotectors may not be evident for weeks, says Borgens, but the effect of PEG is obvious within minutes. In guinea pig experiments reported in the January 2000 Federation of American Societies for Experimental Biology Journal, all of the animals with crushed spinal cords who were treated with PEG regained nerve impulse function: None of those given a sham treatment did. As with neuroprotectors, however, PEG must be applied within 8 hours of injury to be effective, he says.
    One major question that has to be answered is whether PEG can be used with the standard neuroprotectors, says Michel Rathbone, a professor at McMaster University in Hamilton, Ontario, who studies nerve cell growth and repair. "Several drugs have been shown to interact negatively with methylprednisolone, reducing the effect of both," he says. "Therefore they cannot even be used in clinical trials."

    Still, PEG research "seems like a promising approach," says Blight. Surgeons have been using PEG for other purposes, and "if it is clinically proven effective on nerve damage, it may not take long at all for people to start using it there."

  2. #2

    birde

    Borgens, et al. indeed reported the exciting finding that polyethylene glycol (PEG) can help restore axons that have been cut, that it somehow seals the ends of the axons together. They even report that it can be applied as late as a week after the spinal cord is cut. This approach has been practiced in worms, cockroaches, and other invertebrates for years... The finding that it can also be applied to mammals was a subject of some excitment. Please note that axons cut off from their cell bodies will die over time and that this is not a therapy that can be applied to chronic spinal cord injury.

    Wise.

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