Nervios que se regeneran: Neurotransmisores en polímeros estimulan el re-crecimiento del nervioContributed by: Anonymous · Views: 2,839
Contributed by: Anonymous · December 12, 2007 @ 12:31 PM MST · Views: 2,839
Regenerating Nerves: Neurotransmitters in Polymers Stimulate Nerve RegrowthResearch reported December 11 in the journal Advanced Materials describes a potentially promising strategy for encouraging the regeneration of damaged central nervous system cells known as neurons.
Yadong Wang, assistant professor in the Coulter Department
of Biomedical Engineering at Georgia Tech and Emory
University (right), and graduate student Christiane Gumera (left)
have developed a potentially promising strategy for
encouraging the regeneration of damaged central nervous
system neurons. Gumera points to a fluorescence image that
indicates the presence of proteins required for nerve regeneration.
Georgia Tech Photo: Gary Meek
There is currently no treatment for recovering human nerve function after injury to the brain or spinal cord because central nervous system neurons have a very limited capability of self-repair and regeneration.
“Regeneration in the central nervous system requires neural activity, not just neuronal growth factors alone, so we thought a neurotransmitter might send the necessary signals,” said Yadong Wang, assistant professor in the Coulter Department of Biomedical Engineering at Georgia Tech and Emory University, and principal investigator of the study. The research was supported by Georgia Tech, the National Science Foundation and the National Institute of Biomedical Imaging and Bioengineering (NIBIB).
Chemical neurotransmitters relay, amplify and modulate signals between a neuron and another cell. This new study shows that integrating neurotransmitters into biodegradable polymers results in a biomaterial that successfully promotes neurite growth, which is necessary for victims of central nervous system injury, stroke or certain neurodegenerative diseases to recover sensory, motor, cognitive or autonomic functions.
Wang and graduate student Christiane Gumera developed novel biodegradable polymers with a flexible backbone that allowed neurotransmitters to be easily added as a side chain. In its current form, the polymer would be implanted via surgery to repair damaged central nerves.
Fluorescence micrograph of a ganglion on a 70 percent
acetylcholine polymer that shows neurites expressing an
established neuronal marker called synaptophysin. The
bright red spots on the neurites indicate the presence of
synaptic vesicle proteins, which are required for
functional restoration after nerve injury.
Image courtesy of Christiane Gumera
For the experiments, the researchers tested polymers with different concentrations of the acetylcholine-mimicking groups. Acetylcholine was chosen because it is known to induce neurite outgrowth and promote the formation and strengthening of synapses, or connections between neurons. They isolated ganglia nervous tissue samples, placed them on the polymers and observed new neurites extend from the ganglia.
Since these neuron extensions must traverse a growth inhibiting material in the body, Wang and Gumera tested the ability of the biomaterial to enhance the extension of sprouted neurites. More specifically, they assessed whether the ganglia sprouted at least 20 neurites and then measured neurite length and neurite length distribution with an inverted phase contrast microscope.
“We found that adding 70 percent acetylcholine to the polymer induced regenerative responses similar to laminin, a benchmark material for nerve culture,” said Wang. Seventy percent acetylcholine also led to a neurite growth rate of up to 0.7 millimeters per day, or approximately half the thickness of a compact disc.
Laminin is a natural protein present in the nervous tissues, but it dissolves in water, making it difficult to incorporate into a conduit that needs to support nerves for months. A synthetic polymer with acetylcholine functional groups, on the other hand, can be designed to be insoluble in water, according to Wang.
Phase-contrast micrograph of a ganglion on a 70 percent
acetylcholine polymer that shows neurite growth. The figure
is merged from a series of 100x magnification images.
Image courtesy of Christiane Gumera
To provide insights to new approaches in functional nerve regeneration, the researchers are currently investigating the mechanisms by which the neurons interact with these polymers. Since neurons that remain intact after severe injury have only a limited capacity to penetrate the scar tissue, these new findings in nerve regeneration could help compensate for the lost connections.
“This polymer and approach aren’t limited to nerve regeneration though, they can probably be used for other neurodegenerative disorders as well,” added Wang.
This work was funded by grant number R21EB008565 from the NIBIB of the National Institutes of Health (NIH). The content is solely the responsibility of the authors and does not necessarily represent the official view of the NIBIB or the NIH.
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Credits: Georgia Tech Research News