Have researchers finally figured out how to make paralyzed people walk again? Not yet. But they have been able to use electrical stimulation to help an injured man take a few steps.

A team of scientists at the University of Louisville, UCLA and the California Institute of Technology say they were able to help a partially paralyzed U.S. man named Rob Summers, to stand for up to four minutes at a time.

Summers, 25, was paralyzed from the chest down after being hit by a car in a hit-and-run accident in July, 2006. The injury left him with some feeling below his chest but not enough to move his limbs.

Through a combination of physical training and electrical stimulation, the research team was able to get him to stay standing on his own power, at his brain's own command.

"We were able to get him to stand without any support help at the leg. So he was generating enough force to bear his body weight," researcher Dr. Susan Harkema from the University of Louisville reports.

Summers can also voluntarily move his hips, knees, ankles and toes and has regained some sexual and bladder function.

Perhaps most excitingly, with the help of a harness support and some therapist assistance, he can also make repeated stepping motions on a treadmill.

"To be able to pick up my foot and step down again was unbelievable, but beyond all of that my sense of well-being has changed," Summers said in a statement. "My physique and muscle tone has improved greatly, so much that most people don't even believe I am paralyzed."

The results, documented in an article in the medical journal The Lancet, were achieved through something called "continual epidural electrical stimulation" along Summers' lower spinal cord.

The stimulation mimics the signals the brain normally transmits to begin movement. Once that signal is given, the spinal cord's own neural network is able to direct the muscle and joint movements required to stand and step with assistance on a treadmill.

"We need to provide the signal that tells the spinal cord to walk…and then allow the sensory system from the legs, to tell the spine what to do," explained Dr. Reggie Edgerton, a professor of neurobiology and physiological sciences at UCLA Med School.

While there are many researchers around the world trying to repair severed spinal cords by regenerating nerves to allow those with injuries to walk again, this line of research is trying to use the nerve cells that are still available in the injured spine.

Dr. Serge Rossignol, a spinal cord injury researcher at the Universite de Montreal who was not involved in the study, said there are many years of study and experimentation behind the approach.

The results add weight to the idea that electrical stimulation could one day become an effective way to help heal certain types of spinal injuries, he said.

"This is a one-person study and we should not say this is a cure for spinal cord injuries or paralysis," Rossignol told CTV News.

"But it might be an excellent treatment for some people with partial spinal cord injuries who still have some remnant function within the spinal cord."

The researchers say the other key aspect to their achievement was two years of repeated motion training. They suspended Summers over treadmill and had him go through the motions of walking while his spinal cord was being stimulated in an effort to retrain his spinal cord neural networks and to produce the muscle movements necessary to take steps.

After the two years of training, the electrostimulation device was surgically implanted in his back.

The authors hope that some day, people with complete spinal cord injuries will be able to use a portable stimulation unit and, with the assistance of a walker, stand independently and perhaps even walk a few steps.

But they also caution much more research work needs to be done.

"This is a breakthrough. It opens up a huge opportunity to improve the daily functioning of these individuals...but we have a long road ahead," Harkema said in a statement.

Edgerton's team produced similar results on rats by giving them a drug called quipazine that acts on the neurotransmitter serotonin. Once the drugs and electrical stimulation were stopped, the rats were unable to walk on their own.

The drugs used on the rats are not currently licensed for use in humans, but the researchers say they'd like to see further research.

This study was funded by the U.S. National Institutes of Health and Christopher and Dana Reeve Foundation. Susan Howley, the foundation's executive Vice President for Research says the researcher clearly demonstrates "proof of concept."

"It's an exciting development. Where it leads to from here is fundamentally a matter of time and money."

With a report from CTV medical specialist Avis Favaro