Wang and Gumera also tested materials in which their acetylcholine stand-in–known as an acetylcholine-like functional group–and the polymer were combined in different ratios. Neurite growth increased with the concentration of the functional group, up to 70 percent. Materials with concentrations of the functional group higher than 70 percent inhibited neurite growth. The researchers also tested the polymer against laminin, the “gold standard” for neurite growth, according to Wang, and the neurite growth induced by both materials was very nearly the same. Wang plans to begin work on a polymer with functional groups that mimic both acetylcholine and laminin, which he hopes will produce an even stronger effect.
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. “What we are trying to do next is spin the polymer into nano- or submicrofibers.” Since the polymer is made out of polyester, manipulating it into other shapes should be a simple matter, says the University of Texas’s Schmidt.
Under the right circumstances, injured neurons are capable of some regeneration, but scar tissue inhibits their growth. Wang, who has been working on the polymer research for more than three years, thinks that one day surgeons could thread fibers of a polymer studded with growth promoters through scar tissue, guiding neurites to an environment where they can continue to grow of their own accord. “Once you reach the proper environment, it will make the neuron grow very well,” he says. A few millimeters of the fiber inserted surgically would be enough to overcome the repulsing effects of scar tissue.
To treat neurodegenerative diseases like Alzheimer’s, Wang hopes to use the polymer to more efficiently generate neurons that could be transplanted into patients.
Any therapeutic use of the neurotransmitter-mimicking polymer, however, is still years away. “Designing new materials with different functionalities is tough,” says Schmidt. “But this could lead to new results. There is a lot of potential.”