Rodent of the Week: Axons regenerate long after injury

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Scientists have been working for more than a decade on methods to treat spinal cord injuries by attempting to regrow injured nerves. Some success has been achieved in animals that are treated immediately after the injury.

However, new research shows it’s possible to coax the regeneration of nerve axons in rats as long as a year after injury. Axons are the part of the nerve that carries signals away from the nerve body. In the experiment, researchers were able to stimulate the growth of axons in the damaged part of the spinal cord and somewhat beyond the site.

It’s difficult to get injured axons to grow because of scar tissue at the injury site, inflammation and chemical processes that inhibit the growth. Thus, the treatment was dependent on a complex and sophisticated process that included a cellular bridge to the injury site, a nervous-system growth factor to guide axons to the correct target and a stimulus to the injured neurons that turns on genes to promote growth.

Using this formula, researchers were able to demonstrate successful regeneration of axons. Rats that did not receive the full combination treatment did not exhibit growth.

‘The good news is that when axons have been cut due to spinal cord injury, they can be coaxed to regenerate if a combination of treatments is applied,’ the lead author of the study, Dr. Mark Tuszynski of UC San Diego, said in a news release. ‘The chronically injured axon is not dead.

‘While the regenerating axons grow for relatively short distances, even this degree of growth could be useful. For example, restoration of nerve function even one level below an injury in the neck might improve movement of a wrist or hand, providing greater quality of life or independence.’

The study is published in the journal Neuron.

- Shari Roan