Protecting the brain from stroke

It only takes one small clot to cause a stroke. Blocking a blood vessel in the brain, a clot starves cells of oxygen and thus triggers their untimely death. Now a new drug under investigation appears to protect nerves from damage and increase the chance of a recovery.

“When blood flow to the brain is blocked there is an increase in highly reactive, charged molecules called free radicals,” says Jonathan Marshall from the Comparative Cognition Team in Cambridge University’s Department of Clinical Veterinary Medicine. “These are highly dangerous and can cause nerve cells to prematurely die, so we have been working on a compound that mops up the free radicals and therefore save cells from death.”

Working with drug firm AstraZeneca, Dr Marshall has tested the effects of the drug, NXY-059, in monkeys that have undergone a moderate stroke. The researchers monitored the animals’ ability to perform several tasks that required them to reach for food before and after the stroke. They later took samples from these animals to quantify the extent of brain damage.

“Our experiments show that NXY-059 has substantial protective effects,” says Dr Marshall, “not only at reducing the amount of brain damage we observed in samples, but more importantly, at reducing the functional disability that follows a stroke.”

Dr Marshall adds that the most impressive effect of NXY-059 was to reduce the impairment that monkeys sustained in their arms. “Stroke victims often lose motor function on the opposite side to where the brain damage occurs. The monkeys that received NXY-059 readily used their affected arm at near normal levels 10 weeks after the stroke and were more likely to uses their disabled limb. They did not neglect one side of space as is frequently the case in stroke patients.

NXY-059 did not just enhance the natural rate of recovery but also reduced the long-term disability in these monkeys. This is important; large strokes are associated with permanent disability and poor recovery in humans.”

Dr Marshall is continuing his work looking at treatments for stroke. Recently his research team conducted safety testing for NXY-059 in clinical trials; the compound did not cause any adverse side effects. It is now hoped that large scale clinical trials will begin soon to assess the drug’s efficacy in stroke patients.

“The drug may have valuable applications in a wide range of brain damage,” concludes Dr Marshall, “including head injury and birth complications, and reduce long term disability following stroke. It could really help patients regain their lives and provide substantial cost savings to Health and Social Services.”