BBC. Two years ago Darek Fidyka was paralyzed from the chest down. Slow work on the parallel bars has helped him reach the point where he can walk with a frame

A man paralyzed for two years is now walking again, albeit with a frame, after a transplant to his spine. The treatment, to be published in this month's Cell Transplantation, has been under discussion for a while, but has only now shown success.

In 2010, Darek Fidyka was repeatedly stabbed, rendering him paralyzed from the chest down. Fortunately, however, his nose was unscathed.

Olfactory ensheathing glia (OEGs) surround olfactory axons, the nerve fibers that conduct electrical charges from the nose to the brain to allow us to smell. What makes them of interest to spinal patients is that OEGs maintain their capacity to promote new neurons into adulthood.

While some reptiles can grow new tails, for mammals the capacity for regrowth is lost in most of the nervous system. Being an olfactory receptor neuron is stressful, however, as they are forced to respond to the chemicals drawn in with every breath. These neurons usually survive just six to eight weeks, and require constant replacement if we are not to lose our sense of smell. OEGs keep forming paths for new receptor neurons to transmit their messages.

This capacity for regrowth has inspired spinal researchers frustrated by the fact that the mammalian central nervous system does not regenerate axons. The idea is that if OEGs are transplanted into the spinal cord at the point of injury, damaged axons will start to restore themselves.

Animal experiments have produced axon regeneration and even enabled injured rats and dogs to run again

After the attack Fidyka was put on an intensive exercise and physiotherapy program, without success. After two years, he was selected as the subject for the OEG transplant trial, a joint operation between University College London and Wroclaw University Hospital, Poland. Cells from one of his olfactory bulbs were cultured for two weeks before being transplanted through 100 micro-injections around the scar site.

To walk again Darek Fidyka had to have one of his olfactory bulbs removed and cells from it cultured.

BBC TV current affairs program Panorama was invited to film his response to the treatment, and the investment has not been in vain. At first, despite five hours of exercise, five times a week, Fidyka showed no response, but at the three month mark he noticed that his left thigh was putting on muscle. After six months he was able to take faltering steps with the assistance of leg braces and parallel bars.

As the program prepares to go to air, Fidyka is able to walk on his own with the help of a walking frame. Some bladder, bowel and sexual function has also returned. Progress continues, and Fidyka told the BBC, "I think it's realistic that one day I will become independent."

University College's Professor Geoff Raisman, who discovered OEGs, described Fidyka's small steps as "more impressive than man walking on the Moon."