A man who was paralysed from the waist down after a stabbing attack is walking again thanks to pioneering surgery.
Bulgarian patient Darek Fidyka is thought to be the first person in the world to recover from a complete severing of the spinal nerves.
The 38-year-old, who suffered his injury in 2010, now has sensation in his lower limbs and can walk with a frame.
He has been able to resume an independent life - including driving a car. Surgeons used nerve-supporting cells from Mr Fidyka's nose to help the broken tissue grow.
The procedure had only ever been successful in a lab.
Professor Geoffrey Raisman, whose team at University College London's Institute of Neurology discovered the technique, said: "We believe that this procedure is the breakthrough which, as it is further developed, will result in a historic change in the currently hopeless outlook for people disabled by spinal cord injury.
"The patient is now able to move around the hips and on the left side he's experienced considerable recovery of the leg muscles.
"He can get around with a walker and he's been able to resume much of his original life, including driving a car. He's not dancing, but he's absolutely delighted".
A Polish team led by one of the world's top spinal repair experts, Dr Pawel Tabakow, performed the surgery.
While some patients with partial spinal injury have made remarkable recoveries, a complete break was generally assumed to be irreparable.
Prof Raisman added: "The observed wisdom is that the central nervous system cannot regenerate damaged connections. I've never believed that.
"The number of patients who are completely paralysed is enormous. There are millions of them in the world. If we can convince the global neurosurgeon community that this works then it will develop very rapidly indeed".