London: Scientists claim to have repaired brain damage and restored the eyesight of blind animals using a revolutionary treatment based on nanotechnology.

The therapy raises hopes that nanotechnology, the science of the incredibly small, could usher in an era of novel therapies for some of the most debilitating medical conditions, such as strokes and spinal cord damage.

The treatment will require extensive testing in animals before scientists know whether it is safe and effective enough to use on humans, and if so, what kinds of damage it can help repair. But the study's researchers believe it could be used in humans within five years.

Rutledge Ellis-Behnke of the Massachusetts Institute of Technology, who led the research, said the technology could first be used to prevent patients undergoing brain surgery from suffering more damage from the surgeon's scalpel. Injecting nanoparticles into the brain while it was being operated on could, the researchers say, heal nerve damage caused by the removal of a tumour, for example.

The therapy uses tiny particles which, when injected into a damaged part of the brain, spontaneously assemble themselves into a "scaffold" gel which spreads through the damaged area. Tests show that severed nerves later regrow through the scaffold and form new connections.

The treatment exploits the ability of peptides, the building blocks of proteins, to assemble into 3D scaffolds under specific conditions. In the latest research, scientists at the institute used peptides measuring only five billionths of a metre-long which assemble into a fine mesh of woven fibres as soon as they mix with cerebrospinal fluid, the liquid that bathes nerves in the spinal cord and brain.

In tests, injections of the nanoparticles formed a gel that triggered fresh growth of damaged nerves and helped restore the eyesight of 75 per cent of animals, according to the study published in the Proceedings of the National Academy of Sciences.

"We saw the tissue heal itself, which we've never seen before," said Dr. Ellis-Behnke. Repairing nerves in the central nervous system is fraught with difficulty because injuries to the brain or spine usually scar with thick tissue that prevents nerves from regrowing. The body also releases chemicals that hamper nerve growth, a safety mechanism that prevents damaged nerves forming the wrong connections, which could be disastrous.

Dr. Ellis-Behnke believes the therapy stops scar tissue forming and protects damaged nerves, allowing them to regrow only in the damaged area of the brain. In the tests, surgeons made incisions a millimetre or two long in hamsters' brains and injected them with nanoparticles up to 45 minutes later.

After six weeks, most of the animals had regained their sight, while control animals injected only with a saline solution remained blind.

The tests were conducted on 10 young and 16 adult hamsters to check that the therapy worked in older animals, in which nerve growth is limited.

— © Guardian Newspapers Limited 2004

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