Scientists have shown that paralyzed rats have been able to walk again after their spinal cords were bathed in chemicals and zapped with electricity.

An injury to the spinal cord stops the brain controlling the body.

The study, published in the journal Science, showed injured rats could even learn to sprint with spinal stimulation.

Experts said it was an “exceptional study” and that restoring function after paralysis “can no longer be dismissed as a pipedream”.

In 2011, a man from Oregon in the US was able to stand up again while his spinal cord was stimulated with electricity. Rob Summers had been paralyzed from the chest down after being hit by a car.

Now researchers at the Swiss Federal Institute of Technology say they have restored far more movement in rats which became able to run and climb stairs.

Scientists have shown that paralyzed rats have been able to walk again after their spinal cords were bathed in chemicals and zapped with electricity

The spinal cord of the rats was cut in two places. It meant messages could not travel from the brain to the legs, but the spinal cord was still in one piece.

The researchers then tried to repair the damage. The spinal cord was injected with chemicals which stimulated the nerves in the spine and the base of the spinal cord was electrically stimulated as well. The scientists say they were reawakening the “spinal brain”.

However, this was not sufficient to restore movement. The rats were supported in a robotic harness and were shown a treat which they needed to “learn” to walk towards.

The lead researcher, Prof. Gregoire Courtine, said: “Over time the animal regains the capacity to perform one, two steps, then a long run and eventually we gain the capacity to sprint over ground, climb stairs and even pass obstacles.”

He said: “It is completely unexpected to see this recovery, they walk and climb stairs voluntarily.”

The scientists showed that new nerves were forming across the injury and there were also changes in the brain.

This is not, however, a cure for spinal cord injuries in people.

Prof. Reggie Edgerton, from the University of California Los Angeles, was part of the team which helped Rob Summers stand again.

He said the study was “important” and that it was becoming clear that engaging the brain was the key.

“You’ve got to make the rat want to step, it demonstrates the importance of training and rehabilitation,” he said.

How this works is still unknown. Prof. Reggie Edgerton speculated that “we are activating the spinal cord to a critical level” close to the level which would trigger movement, and a small signal from “the brain pushes it over” leading to movement.