Protein in human hair shows promise for regenerating nerves

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Protein in human hair shows promise for regenerating nerves

http://www.eurekalert.org/pub_releases/2008-01/wfub-pih011008.php

A protein found in human hair shows promise for promoting the

regeneration of nerve tissue and could lead to a new treatment

option when nerves are cut or crushed from trauma.

In the current issue of Biomaterials, scientists from Wake Forest

University School of Medicine reported that in animal studies the

protein keratin was able to speed up nerve regeneration and improve

nerve function compared to current treatment options.

" We found that the nerve repair happened more quickly and

consistently, and that functional recovery was higher, " said Mark

Van Dyke, Ph.D., senior author and an assistant professor of

regenerative medicine. " The fact that we were able to accomplish

this with gels made from keratin is pretty remarkable. "

Current treatments for repairing damaged nerves include microsurgery

to sew two ends of the nerve together, using a nerve from another

part of the body to replace a damaged section, or placing an empty

tube between the cut ends so that nerve fibers can grow through it

and back into the muscle.

Grafting a nerve from another part of the body is usually the most

effective option, but it creates another injury site and isn't

possible in all patients. The tubes, known as nerve guidance

conduits, cannot be used in gaps longer than three or four

centimeters. In addition, nerve regeneration with this method is not

always successful. For example, after about age 17, nerves don't

regenerate as well.

Laboratory scientists have tried placing natural materials, such as

collagen, into the conduits to promote nerve regeneration. Van

Dyke's team was the first to use keratin, which is believed to

contain molecules that regulate cell behavior.

The scientists collected human hair from a local barber shop and

chemically processed it to remove the keratin. They purified the

keratin protein and used it to form gels that were then used to fill

the nerve guidance conduits. They studied how keratin affects the

activity of Schwann cells, which play a vital role in nerve

regeneration. These cells produce signals that tell nerve cells to

begin regenerating and " remodel " the blood clot that has formed so

that nerve cells can grow across it.

" By using keratin to activate these cells, we're trying to tap into

the natural healing cascade, " said Van Dyke. " We believe that

keratin helps amp up Schwann cell activity and give the nerve

regeneration process a head start. "

The laboratory studies showed that keratin activated Schwann cells

and increased their proliferation and migration. Next, the

scientists used a keratin-filled tube to attempt to repair a 4

millimeter nerve gap in mice -- a fairly significant gap considering

the size of the animal.

The results from these animals were compared with animals treated

with an empty nerve guidance conduit and with animals treated with a

nerve graft.

After six weeks, 100 percent of the animals in the keratin and nerve

graft groups showed visible nerve regeneration across the gap,

compared to only 50 percent who got the empty conduit. The speed of

repair was best in the keratin group.

The scientists then tested the function of the regenerated nerve.

The speed of nerve impulses was best in the keratin group. The

amount of signal that got through the nerve was better in the

keratin group than in the empty tube group. The study was recently

highlighted in the journal Science.

" The results suggest that a conduit filler derived from hair

keratins can promote an outcome comparable to a grafted nerve, " said

Van Dyke.

In the study, the nerve function did not translate into recovery of

muscle function, but the scientists suspect they may have tested too

early, before the nerve had time to regenerate to the muscle. It is

known that muscle function recovery lags behind nerve recovery.

Future studies will focus on regeneration across larger gaps and

will test whether nerve regeneration results in a return of muscle

function.