Not many of us get to keep a promise to Superman, but a man visiting Auckland says he is on track.

When the star of Superman, Christopher Reeve, was paralysed from the neck down after falling off a horse in 1995, he challenged Dr Wise Young to find a cure that would make him walk again.

Young is leading clinical trials in China, the US, Norway and India that he believes will make this happen.

The cure will be too late for Reeve, who died in 2004, but Young asserts his research will bring hope to spinal injury sufferers who science previously wrote off as untreatable.

Young is the founding director of the W M Keck Center for Collaborative Neuroscience and a professor at Rutgers, the State University of New Jersey.

"It's achievable not just within our lifetime, but within a few years," said Young. "It's a matter of getting the therapies that are making rats walk into humans."

Young has injected stem cells from umbilical cord blood and lithium into patients' damaged spinal cords. He expects the cells to migrate into the injury site and form a bridge. Lithium is used to stimulate growth.

Young said patients would not need to be completely healed to regain their function. Restoring 10 per cent of the spinal cord would be enough to transform their lives - and even make them walk again.

"We don't have to regenerate the whole spinal cord - we just have to regenerate enough to reach a functional threshold," he said.

Young's visit coincides with the start of a New Zealand-based clinical trial led by the Spinal Cord Society.

Trial co-ordinator Dr Jim Faed, of Otago University Medical School, is recruiting 12 people with spinal cord injuries to take part in the study.

The patients will have stem cells from their own Nasal tissue implanted into their spinal cords.

It will take 2 years to discover if the treatment works.