http://news.bbc.co.uk/hi/english/health/newsid_1696000/1696053.stm

Thursday, 6 December, 2001, 16:56 GMT

Scientists have managed to make damaged nerves re-grow to fill gaps of more than a centimetre, adding to hopes for treatments for spinal injury.

The team from the University of Munster in Germany carried out experiments on the severed optic nerves of rats.

However, they are thought to be good models for the human spinal cord - and scientists believe this, combined with other techniques, may provide a way to help people whose cords have been severed or left badly damaged.

Normally, axons - the long strands of nerve tissue which make up the fibres, are highly resistant to regrowth in such circumstances.

They normally start sprouting out - but never get very far.

Scar block

This is because the scar tissue at the site of the injury prevents the severed ends growing out, even prompting the exposed tip of the nerve to release a protein which instructs the nerve not to regrow.

The German team were testing one method of overcoming this resistance.

Within the lens of the eye are proteins called crystallins which they believe stop the nerve tip protein having its inhibitory effect.

Punctured eye

They performed an operation to rejoin the two ends of the sheath which normally surrounds the nerve fibres, then punctured the lens of the eye.

The results were spectacular - in one instance 14mm of nerve regrowth was produced.

Three months later, approximately 30% of the nerve fibres had regenerated, which, according to the team, could be enough to produce some vision.

Other research has shown that lens injury can promote nerve regrowth in these sorts of injury.

However, this is most pronounced growth yet seen, and some experts suggest that the effect of the surgical "sticking together" of the sheath ends contributes by inflaming the surrounding tissue, which then produces chemicals which help the nerves grow.

Dr James Fawcett, from the Cambridge Centre for Brain Repair, says that any successful attempt to produce nerve regrowth in humans would probably depend on a combination of treatments, both aimed at breaking down scar tissue and encouraging nerves to sprout.

He said: "Lots of things can affect the ability of the axon to regenerate, and we a looking for ways to 'juice it up'."