For more than a decade, the drug tPA has proven its worth as the most effective emergency treatment for the most common kind of stroke but its promise is blemished because: tPA can cause dangerous bleeding in the brain and its brain-saving power fades fast after the third hour of a stroke.

Researchers at the University of Michigan and the Ludwig Institute at the Karolinska Institutet in Stockholm, Sweden, found tPA in mice causes the blood-brain barrier to leak but mice taking the leukemia drug imatinib, also known as Gleevec, had 33 percent less leakage than those that didn't and 34 percent less damage to the brain.

"Together with our clinical colleagues at the Karolinska University Hospital in Stockholm we are now rapidly continuing to explore this exciting possibility in clinical trials involving stroke patients," study leader Ulf Eriksson of the Karolinska Institute.

The findings are published online in Nature Medicine.