JERUSALEM (Reuters) - Israeli doctors said on Thursday a clinical trial on paraplegics had shown success at repairing severed spinal cords and restoring movement to paralyzed people.

Melissa Holley, an 18-year-old American girl, underwent the treatment in Israel last year after she was left a paraplegic following a car accident.

Twelve months later, her doctor said, she has regained movement in her toes and legs and has bladder control, improving her quality of life and reducing chances of a urinal infection that is a common cause of death among paraplegics.

Holley became the first person to undergo the treatment -- previously tested only on rats -- after she crushed two vertebrae and severely damaged her spinal cord in a car accident in the United States.

"She couldn't move. She couldn't feel anything," said Dr. Valentin Fulga, whose company, Proneuron Biotechnologies (Israel) Ltd, developed the treatment.

He said Holley began regaining sensation several months after white blood cells called macrophages were injected into her spinal cord at Tel Hashomer hospital near Tel Aviv last July.

The body uses macrophages to heal wounds and regenerate tissues.

"She recovered very significant motor function in her legs, although she is not yet walking," Fulga said.

Holley's father came across the Proneuron Web site offering to bring paraplegics to Israel for the experimental treatment.

Fulga wanted, in first-stage trials, to test the method on at least five more people who had "no sensation, no motor function below the site of the injury."

BREAKTHROUGH ON NERVE DAMAGE

The treatment is based on research by Professor Michal Schwartz from Israel's Weizmann Institute of Science, who found that by injecting treated macrophages in rats she was able to restore nerve function in about 60 percent of cases.

Fulga said the scarcity of macrophages in the central nervous system was the main reason severe spinal injuries were permanent.

He said Schwartz's research and the initial trials showed that macrophages activated to treat wounds and injected in the spinal column slowly began to repair nerve fibers.

Dr. Nachson Kenoller, a neurosurgeon who has performed the procedure on three people, said the spinal cord and brain had been considered areas where regeneration was impossible.

"We are talking about regeneration of the spinal cord, which has never been recorded in the past," Kenoller told Reuters.