Drug 'helps repair stroke damage'

Strokes can cause extensive brain damage

A simple, naturally-occurring chemical could actually help nerve cells grow following a stroke, according to US scientists.

If their experiments, so far confined to animals, also prove successful in humans, it could be a landmark for stroke treatments.

A stroke happens when a small part of the brain is deprived of its blood supply, either because a clot has blocked a blood vessel, or the vessel has burst open.

Even if the problem only lasts a short time, the damage can be extensive, and leave the patient disabled, or even kill.

Those who survive can face months of therapy to recover proper movement in limbs, or speech, and some never manage this entirely.

The study shows that Inosine induces a great deal of rewiring in the brain after stroke

Professor Larry Benowitz, Harvard Medical School

Part of this recovery process involves the brain "re-wiring" itself, so that functions controlled by the permanently damaged area are picked up elsewhere.

Up until now, there have been no potential drugs which encourage nerves in the brain to do this.

The research by Professor Larry Benowitz at Harvard Medical School focuses on Inosine a chemical which has shown startling results in rat experiments.

Rats treated with Inosine after a stroke showed greater ability to move their affected paws than untreated rats - regaining almost normal ability after 19 days, while untreated rats only regained half.

Their ability to swim - another key indicator of limb function - also improved after Inosine compared with no treatment.

Scans of the rat's brains backed this up - with clear evidence of new connections in various brain areas.

Professor Benowitz said: "The study shows that Inosine induces a great deal of rewiring in the brain after stroke.

"This rewiring is apparently sufficient to promote substantial functional recovery."

Dr Patrick Anderson, a researcher from University College London, said that it would be a "landmark" if the findings could be reproduced in humans.

He said: "There have been a number of disappointments in drugs that attempt to reduce the amount of damage to brain cells after a stroke, but this would be the first which actively encourages regeneration."

In addition, rats improved even if given the drugs 24 hours after their stroke.

Dr Anderson said: "This would be very advantageous - the majority of strokes happen at night."

The research is published in the journal Proceedings of the National Academy of Sciences.