Researchers say the anti-cancer drug Taxol, normally used to treat breast cancer, might also hold promise as a way to help people recover from crippling spinal cord injuries.
Researchers at Max Planck Institute of Neurobiology in Germany report that Taxol improves movement and function in rats with spine injuries, by promoting nerve regeneration. They say the drug appears to eliminate the physical obstacles that normally prevent injured nerve cells from regrowing axons.
Axons are the long slender projections that transmit nerve-cell impulses to the rest of the body, controlling movement. Recovery from spinal cord injuries is often impossible because of the formation of scar tissue, which impedes the growth of new nerves.
But in experiments with rats whose spinal cords had been partially cut, researchers saw that Taxol stimulated nerve regeneration around the scar tissue.
Lead investigator Frank Bradke likens scar tissue formation to "stop signs" that impede the regrowth of nerve fibers. "So, we saw that we could basically make axons grow over these stop signs, so that they can start to grow like a crazy driver," he said.
Bradke says Taxol promotes axonal regeneration indirectly - by helping to reduce scarring.
He says the drug also loosens microtubules, tiny protein structures that make up rigid internal cell structures or mini bones of the spine. By loosening what Bradke calls this "fishing net" of microtubules, Taxol gave the nerve filaments room to grow.
In the rat experiments, the injured animals could still move before treatment with Taxol. But their walking ability and coordination improved markedly after the drug was injected continuously at the site of their spinal injuries for four weeks. "What is pretty exciting about the work is that you basically have a drug that is already clinically approved. OK? And we know quite a lot about Taxol, so Taxol (has been) in the clinic for 20 years. And I think what is also cool is that we use it in a much lower concentration than you would use it in anti-cancer treatment, and you also only apply it locally," he said.
Meaning the drug is likely to have fewer side effects than when it’s used to treat cancer. But Bradke says while Taxol appears to improve function, it cannot completely heal a serious spinal cord injury.
An article describing spinal nerve regeneration experiments with the anti-cancer drug Taxol is published this week in the journal Science.