New Story - Nerve Regeneration

[Guest guest]

(This is the whole story from the link I previously sent. Not sure if it

worked) ~ G

Source:

Washington University In St. Louis (http://www.wustl.edu/)

Date:

Posted 7/26/2002

New Horizons Of Nerve Repair:

Biomedical Engineer Trips Up Proteins In Nerve Regeneration System

It's sticky, it's a gel, it comes in a tube, but this is no greasy kids'

stuff. Rather, it's a novel delivery system for peripheral nerve

regeneration that could have implications for successful stem cell

delivery and spinal cord repair.

Sakiyama-Elbert, Ph.D., assistant professor of biomedical

engineering at Washington University in St. Louis, has designed a system

that employs a nerve guide tube filled with a gel containing growth

factor proteins that stimulate nerve

regeneration. Also part of the package are strategically placed sugars

and peptides for binding in the gel matrix. The system has promoted

peripheral nerve regeneration in preliminary rat studies.

The clinical Gold Standard for peripheral nerve regeneration involves

taking a nerve from a donor site on the injured person's body and sewing

the donor nerve in between the two ends of the injured nerve. Though the

nerve is dead, it provides a pathway that can guide the regeneration of

the injured nerve. This is problematic because it creates an injury to

be addressed at the donor site, and there is a limit to the amount of

donor tissue you can use from a patient. Furthermore, there is no

guarantee that the donated nerve will come to life in a new site.

Another alternative is the use of cadaver nerves, which runs a risk of

rejection.

Sakiyama-Elbert, working with famed plastic surgeon Mackinnon

,M.D., Syd. M. and H. Shoenberg Professor of Surgery of the

Washington University Medical

School, places exogenous sticky material capable of binding growth

factors throughout the gel, causing the growth factor proteins to remain

in the gel for months because they keep tripping over the sticky

material. These binding sites can be tuned according to how fast the

drug needs to be released for successful regeneration. Timed release is

a key component of her system, because a real limitation is having the

proteins diffuse out in a day or two, which is the case with many

currently used systems.

Sakiyama-Elbert recently presented these results at a conference hosted

by the Plastic Surgery Research Council, April 18-20, in Boston. Her

work is sponsored by the Whitaker Foundation.

Another approach to peripheral nerve regeneration that Sakiyama-Elbert

is testing involves creating her own protein consisting of a growth

factor, and two different domains, a cross-linking site and a substrate

for an enzyme that cleaves the growth factor at just the time a

regenerating nerve cell would be migrating through the matrix. This

cell-activated drug delivery system is also incorporated into a gel and

delivered from a nerve guide tube, and it's a great example of a new

area known

as biologically responsible materials.

Stem cells for spinal cord repair

She also is one of very few researchers looking into matrixes for spinal

cord damage, such as the kind that actor Reeves suffered

years ago and from which he is not recovered. She is collaborating with

Mc, M.D., Ph.D.,assistant professor of neurobiology at the

Washington University School of Medicine. Mc already has treated

spinal cord injuries in rats with embryonic stem cells; the

problem is that most of the stem cells died after transplantation.

Sakiyama-Elbert is hopeful that her matrix/tube delivery system will

allow 50 to 75 percent survival of the stem cells by providing a more

hospitable environment for the cells immediately after transplantation.

" The overall goal of this direction of my research is to apply novel

bioengineering technology to allow controlled release of growth factors

from scaffolds that facilitate the regeneration of adult spinal cord

axons through and beyond spinal cord

lesions, " Sakiyama-Elbert said. " The scaffolds are drug-delivery systems

consisting of protein matrices containing growth factors that are

released in a sustained manner during tissue regeneration. "

The scaffolds can be further modified by adding embryonic stem cells

during polymerization, a process where small molecules are combined

together to form larger ones.

" The embryonic stem cells can repopulate the injured spinal cord and

serve as a source of nerve growth factors during regeneration, "

Sakiyama-Elbert explained.

Note: This story has been adapted from a news release issued by

Washington University In St. Louis for journalists and other members of

the public. If you wish to quote from any part of this story, please

credit

Washington University In St. Louis as the original source. You may also

wish to include the following link in any citation:

http://www.sciencedaily.com/releases/2002/07/020725082253.htm