Posted: October 14, 2009 |
Bioengineering of nerve-muscle connection shows potential to restore sense of touch |
(Nanowerk News) Modern tissue engineering developed at the University of Michigan could improve the function of prosthetic hands and possibly restore the sense of touch for injured patients.
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Researchers will present their updated findings Wednesday at the 95th annual Clinical Congress of the American College of Surgeons.
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The research project, which was funded by the Department of Department of Defense, arose from a need for better prosthetic devices for troops wounded in Afghanistan and Iraq.
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"Most of these individuals are typically using a prosthesis design that was developed decades ago," says Paul S. Cederna, M.D., a plastic and reconstructive surgeon at U-M Health System and associate professor of surgery at the U-M Medical School. "This effort is to make a prosthesis that moves like a normal hand."
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U-M researchers may help overcome some of the shortcomings of existing robotic prosthetics, which have limited motor control, provide no sensory feedback and can be uncomfortable and cumbersome to wear.
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"There is a huge need for a better nerve interface to control the upper extremity prostheses," says Cederna.
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When a hand is amputated, the nerve endings in the arm continue to sprout branches, growing a mass of nerve fibers that send flawed signals back to the brain.
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The researchers created what they called an "artificial neuromuscular junction" composed of muscle cells and a nano-sized polymer placed on a biological scaffold. Neuromuscular junctions are the body's own nerve-muscle connections that enable the brain to control muscle movement.
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That bioengineered scaffold was placed over the severed nerve endings like a sleeve.
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The muscle cells on the scaffold and in the body bonded and the body's native nerve sprouts fed electrical impulses into the tissue, creating a stable nerve-muscle connection.
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In laboratory rats, the bioengineered interface relayed both motor and sensory electrical impulses and created a target for the nerve endings to grow properly.
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"The polymer has the ability to pick up signals coming out of the nerve, and the nerve does not grow an abnormal mass of nerve fibers," explains Cederna.
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The animal studies indicate the interface may not only improve fine motor control of prostheses, but can also relay sensory perceptions such as touch and temperature back to the brain.
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Laboratory rats with the interface responded to tickling of feet with appropriate motor signals to move the limb, says Cederna.
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