Darek Fidyka was stabbed in 2010. The knife attack left an 8 mm gap in his spinal cord, paralyzing him from the chest down. He spent two years in rehabilitation and medical programs but still couldn't walk. His condition hadn't improved until 2014, two years after he was treated with olfactory ensheathing cells.

University College London's  professor Geoff Raisman, who discovered olfactory ensheathing cells, explained how spinal cord injuries can affect patients.

"The problem with spinal injury is that nerve fibers are severed by the injury so that impulses that carry movement—the desire for movement—down from the brain to the body are cut off. Impulses carrying sensations up from the body to the brain are cut off," he said.

"Three months later, Fidyka's improvements were miraculous."

A team of scientists at the University College London developed the stem cell treatment involving olfactory ensheathing cells. They took the cells from Fidyka's nose and transplanted them above his spinal cord gap. They then used nerve tissue taken from his ankle to use as a bridge so the cells could grow across.

Three months later, Fidyka's improvements were miraculous. His thigh muscles began growing, and he started walking with leg braces and with the help of a doctor.

"When you can't feel almost half your body, you are helpless, but when it starts coming back it's as if you were born again," Fidyka said.

Stem cells have the unique ability to transform into other cells in the body, such as muscle or red blood cells, or remain a stem cell. They act to repair damaged body parts by helping to replenish lost cells.