A man was able to walk again after undergoing pioneering therapy to transplant cells from his nasal cavity to his spinal cord.
Darek Fidyka was paralyzed from the chest down after being stabbed repeatedly in the back in an attack that happened in 2010, now he can walk using a support.
BBC Medical Correspondent Fergus Walsh explains that the pioneering treatment was carried out by surgeons in Poland in collaboration with scientists from London, UK.
Details of the research were published in the journal Cell Transplantation.
A BBC television program, Panorama, had exclusive access to the project and spent a year monitoring the patient's rehabilitation.
To be born again
Fidyka, 40, said walking again is an "incredible feeling."
He added: "When you can not feel almost half of your body, you are helpless, but when you start to recover, it is like being reborn."
Geoff Raisman, chief of neuronal regeneration at the Institute of Neurology at University College London, led the British research team.
Raisman noted that what was achieved is "more impressive than seeing the man walking on the moon."
Pawel Tabakow, a neurosurgeon at Wroclaw University Hospital, who directed the Polish team, said: "It is fascinating to see how regeneration of the spinal cord, something that was considered impossible for many years, becomes a reality."
The treatment used special cells that are part of the sense of smell and are called olfactory wrap-around cells (OEC).
OECs facilitate the renewal of nerve fibers in the olfactory system.
In the first of two operations, the surgeons removed one of the olfactory bulbs and cultured the cells.
Two weeks later they transplanted the OEC to the spinal cord, which had been severed by the knife with which Fidyka had been attacked, except for a small piece of scar tissue on the right side.
They had only one drop of material to work with - about 500,000 cells.
About 100 microinjections of OEC were performed above and below the lesion.
Three, six and 24 months
Four thin strips of nerve tissue were taken from the patient's ankle and placed on a 8mm gap to the left of the spinal cord.
Scientists believe that the CSOs served as a way to reconnect the fibers above and below the lesion, using nerve grafts to close the gap in the marrow.
After the transplant Fidyka continued with a rehabilitation program that had not yielded any results for two years.