Nerve bridge mends severed spinal cord

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Nerve bridge mends severed spinal cord

New growth of nerve cells are rat back control of their bladder function

Hope for many paraplegics: US researchers have succeeded for the first time to repair in rats a severed spinal cord at least partially. A special enzyme cocktail they brought implanted nerve piece to bridge the gap. This allowed the animals not walk again, but they could at least control their bladder function. For many would be paralyzed this is a great improvement in their quality of life.

Nerve bridge mends severed spinal cord

Cross-section of the human spinal cord

© Time3000 / CC-BY-SA 2.5 US

While able to regenerate almost all tissues of the body after an injury again and grow, this does not apply to many nerve fibers. The researchers found already established nearly a century ago. At that time she already tried severed spinal cord nerve by nerve inserted pieces of the arms or legs to be bridged. But the implanted nerve bridges did not grow and did not initiate any signals from the brain to the lower body regions.

Recently, studies have also shown why this is, among other things: preventing specific, distributed at the injury site substance that neurons form long streamers of the bridge and connect through these fibers to the spinal cord. Instead, she makes sure that scar tissue is formed, which prevents inflammation, but also the growth of nerves.

Nervous piece and substance Cocktail

To overcome this obstacle, combined Yu-Shang Lee and his colleagues at Case Western Reserve University in Cleveland now several treatment approaches. In their experiment, they initially transected rat spinal cord at the level of the eighth thoracic vertebra. As a result, the animals were paralyzed and lost control of her bladder. "Because the storage and release of urine is complex in most animals and humans, and requires information from both the bladder and the Harngängen and from the brain," the researchers explain. With Severing the spinal cord, this no longer works.

Planted Next Lee and his colleagues the animals a small piece of a nerve ribs at the destroyed spinal cord site. In order to prevent scar formation and to promote the growth of the nerve, they then injected a cocktail of an enzyme, known as chondroitinase, and a growth factor to the nerve endings. To check some more paralyzed rats received only one component of this cocktail or a saline solution.

Nerve bridge mends severed spinal cord

Laboratory animal rat

© IMSI Master Clips

New nerve connections to bridge gap

Three months after this treatment, a first effect showed how the researchers report: "The animals that received the triple combination, although could not walk again, but they were gradually a remarkable control over their bladder function," says Lee. After six months, patients treated with nerve patches and substance cocktail rats spent almost as much again as urine from healthy control animals. This was the first time that you've restored by nerve regeneration bladder function after such a spinal cord injury, so the researchers.

Further investigations revealed that new nerve connections between the spinal cord and the implanted nerve bridge arose. As the scientists explain, the growth factor stimulated the formation of long, unbranched nerve ends, the enzyme chondroitinase prevented the formation of blocking scars and also helped to make the axons grow straight.

Regeneration of nerve fibers from the brain stem

"It is particularly surprising and exciting was the fact that a variety of nerve cells in the brainstem under these favorable conditions until well into the spinal cord grew into," said study leader Jerry Silver of Case Western Reserve University in Cleveland. The foothills of these cells overcame not only the severed body and the nerve bridge, but still stretched beyond.

Why just these neurons possess such regenerative capacity, is still unclear. "But that figure is a particularly important issue for the future," explains Silver. Because if you know it, one might transmit this ability one day to other nerve cell types - for example, those that transmit the signals for movements of the legs. First, however, further studies are needed only once in order to improve the process to such an extent that this will restore bladder function can be restored in people. (The Journal of Neuroscience, 2013;
doi: 10.1523 / JNEUROSCI.1116-12.2013 )

(Journal of Neuroscience, 26/06/2013 - NPO)


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Paraplegia spinal nerves bridge nerve fiber growth factor paralysis bladder function spinal brainstem Medicine

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