Don Fitch, from Pittsburgh, is one of the first 12 people in the world to undergo the new treatment. His progress is featured in the BBC One television programme Tomorrow's World on Wednesday.

Don hopes to regain the use of his left arm three years after a stroke left his left side partially paralysed.

A small area of Don's brain was damaged when a clot lodged itself in his brain.

Until now, scientists have been unable to reverse the effects of brain damage as brain cells, known as neurones, could not be repaired once they were damaged.

Don Fitch: Lost use of his arm

But Don plans to take advantage of a new technique that has given stroke victims hope of at least a partial recovery.

He is to have millions of manufactured human nerve cells - made from cells taken from testicles - implanted into his brain.

Scientists believe the new cells will link up with existing brain cells to repair the damage caused by the stroke.

Neurosurgeon Douglas Kondziolka, who leads the surgical team, said: "We are going to put the cells not just into the stroke area, but beyond it and hope that the cells will then graft, link up with the existing brain cells that are still livings and create a better regional environment - an environment that perhaps wants to move the arm."

Douglas Kondziolka: Developed the technique

The operation has become possible because scientists stumbled upon a new way of growing nerve cells in the laboratory.

They discovered that they can take immature cells from a testicular tumour, stimulate them to replicate many times and then treat them with a body chemical to turn them into nerve cells suitable to transplant into the brain.

Dr Kondziolka said: "These cells will hopefully help the local environment to release different types of growth factors, neurotransmitters, and help the brain talk to itself better and translate into better function."

The operation itself is relatively quick and is carried out under local anaesthetic.

A single hole is drilled through the skull, and a tube is inserted into the brain to deliver the cells.

If the brain cell transplants prove to be safe and effective the procedure could be used for many forms of brain damage, from Parkinson's Disease to head injuries.

Don will have to wait for six months to find out if the surgery is a success.

"It's all over bar the shouting, and when my arm starts moving I am going to start shouting," he said.