Scientists have taken a major step towards repairing severed spinal cords after discovering a way to make sure nerves "rewire" themselves correctly.
Back and neck injuries often result in paralysis because, unlike peripheral nerves, the "wires" of the spinal cord do not naturally mend themselves. Researchers have now shown that if they are attached to the right places the severed wires, or axons, will regenerate.
Scientists conducting the research at the University of California, San Diego (UC San Diego), showed that by using a biological chemical, the nerve's fibres could be guided to their correct targets. The chemical, neurotrophin-3 (NT-3), not only steered the "wires" the right way but also supported the formation of synapses, which are nerve connection points.
Two other treatments were needed at the same time – a cell "bridge" placed across the spinal cord injury site, and a "conditioning" stimulus to turn on the body's regenerative genes. But if the chemical was not located precisely enough, the nerve fibres grew into the wrong region.
A paper about the research was published yesterday in the journal Nature Neuroscience. Despite overcoming a huge hurdle, the team still need to work out how to create electrically active and functioning spinal-cord connections.
Professor Mark Tuszynski, director of the Centre for Neural Repair at UC San Diego, said: "While our findings are very encouraging... they also highlight the complexity of restoring function in the injured spinal cord."