Bioengineering of nerve-muscle connection could improve hand use for wounded sol

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Bioengineering of nerve-muscle connection could improve hand use for wounded

soldiers

Animal studies at University of Michigan also show potential to restore sense of

touch

http://www.eurekalert.org/pub_releases/2009-10/uomh-bon101309.php

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.

Researchers will present their updated findings Wednesday at the 95th annual

Clinical Congress of the American College of Surgeons.

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.

" Most of these individuals are typically using a prosthesis design that was

developed decades ago, " says 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. "

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.

" There is a huge need for a better nerve interface to control the upper

extremity prostheses, " says Cederna.

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.

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.

That bioengineered scaffold was placed over the severed nerve endings like a

sleeve.

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.

In laboratory rats, the bioengineered interface relayed both motor and sensory

electrical impulses and created a target for the nerve endings to grow properly.

" 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.

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.

Laboratory rats with the interface responded to tickling of feet with

appropriate motor signals to move the limb, says Cederna.

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The Department of Defense and the Army have already provided $4.5 million in

grants to support the research. Meanwhile, the research team has submitted a

proposal to the Defense Advance Research Project Agency to begin testing the

bioengineered interface in humans in three years.

Addtitional U-M authors of the study include M. Kuzon, Jr., M.D., Ph.D.,

head of plastic surgery and professor of surgery; C. , Ph.D.,

professor of biomedical engineering; Daryl R. Kipke, Ph.D., professor of

biomedical engineering;