People suffering of injury to the brain or spinal cord cannot currently be treated because central nervous system neurons have a very limited capability of self-repair and regeneration. But now, researchers from the Georgia Institute of Technology have developed a potentially promising strategy for encouraging the regeneration of damaged neurons. Their new technique uses "a biodegradable polymer containing a chemical group that mimics the neurotransmitter acetylcholine to spur the growth of neurites." According to the scientists, this method could be used to treat neurodegenerative diseases like Alzheimer's in a few years.
As you can see on the left, this research work made the "inside front cover" of the December 2007 issue of Advanced Materials. Here is the caption for this front cover (Credit: Advanced Materials). "Primary neurons respond to acetylcholine functionalities in polymers in a dose-dependent manner. The control of the interactions between a biomaterial and neurons may enable novel clinical treatments for neurological disorders. Here, the repeating unit of the polymer is shown on top of neurites extending from the dorsal root ganglia cultured on the polymer."
This research work was published in Advanced Materials under the title "Modulating Neuronal Responses by Controlled Integration of Acetylcholine-like Functionalities in Biomimetic Polymers" (Volume 19, Issue 24, Pages 4404-4409, December 2007). Here is a link to this communication.
This research project has been led by Yadong Wang, assistant professor in the Coulter Department of Biomedical Engineering at Georgia Tech and Emory University, with the help of graduate student Christiane Gumera. You can find more information by visiting the Wang lab website, and more specifically, this page about Neurotransmitter-based biomaterials.
Here are some comments made by Wang for the Georgia Tech news release. "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. [...] One of our ultimate goals is to create a conduit for nerve regeneration that guides the neurons to regenerate, but gradually degrades as the neurons regenerate so that it won’t constrict the nerves permanently."
Now, how the researchers made their experiments? "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."
And what were the results obtained? "'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."
This research project has also been mentioned in Technology Review under the title "Regenerating Nerves" (Eric Bland, January 2, 2008). Here is how Bland describes the project. "Previous research has identified several agents that can stimulate the regrowth of nerve cells, or neurons, a protein called laminin foremost among them. But laminin is water soluble and dissolves quickly in the water-based environment of the body. The Georgia Tech researchers' material worked as well as laminin, but because it is water insoluble, it is more likely to stay in place if inserted into a patient's body, and it could stimulate the growth of nerve cells for weeks instead of days."
And what's next? "Wang is also working to fabricate the polymer in configurations that would be more therapeutically useful. 'Right now we just have a flat coating of polymer,' he says. [...] To treat neurodegenerative diseases like Alzheimer's, Wang hopes to use the polymer to more efficiently generate neurons that could be transplanted into patients."
Sources: Georgia Institute of Technology news release, December 11, 2007; and various websites
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