Polymer scaffolds may restore damaged nerves


By Duncan Graham-Rowe A polymer laced with chemicals that mimic a key neurotransmitter can trigger the regeneration of damaged nerve cells, research shows. Eventually, scaffolds made from the material might help restore sight in people with damaged optic nerves, by encouraging new neurons to develop. One of the problems with restoring damaged nerves is that some do not respond to growth factors unless also stimulated by neuronal activity, which decreases dramatically when damaged occurs. “It’s a catch-22 situation,” says Yadong Wang of the Georgia Institute of Technology in Atlanta, US. Wang and graduate student Christiane Gumera developed a polymer laced with chemicals that mimic a neurotransmitter called acetylcholine, which relays, amplifies, and modulates signals sent between neurons. The hope was that the polymer could trigger a regenerative reaction in damaged nerve cells. “The polymer’s ‘backbone’ is like a string,” says Wang. “But every once in a while there’s a branch coming off which has a chemical that mimics a neurotransmitter.” Tests on cultured cells show that the polymer simulates the growth of neurites – the fibre-like projections that connect neurons – at a rate of 0.7 millimetres a day. Next the researchers plan to use honeycomb-like scaffolds made from the polymer to encourage nerve regeneration in rats. These structures might not only stimulate nerve regeneration, but also direct its growth. “We could use these to bridge severed nerve ends,” says Wang. Since the polymer is biodegradable, the scaffolds should also safely break down when the job is down. Wang believes that there is scope to use similar scaffolds to repair spinal injury. However, Martin Schwab, at the Brain Research Institute at the University of Zurich, in Switzerland, is not so convinced. The real problem with nerve regeneration is that scar tissue forms at the site of an injury, he says. “This scar tissue acts like a wall,” blocking regenerating nerves from passing through, Schwab told New Scientist. Wang admits that scar tissue could be a major problem. But he is hopeful that the polymer might be used to treat neurodegenerative disorders another way – by stimulating stem cells to differentiate into neurons. “We have preliminary data to suggest that this may be possible,” he says. “But we need to do more experiments to prove it.” Journal reference: Advance Materials (DOI: 10.1002/adma.200701747) Mental Health – Discover the latest research in our continuously updated special report. The Human Brain – With one hundred billion nerve cells, the complexity is mind-boggling. Learn more in our cutting edge special report. More on these topics:
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