Vampire Bat Saliva Could Lead to Stroke Treatment

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Joel Sartore / National Geographic via Getty Images

Vampire bats have a well-known trick for getting the most blood out of their victims: an enzyme called desmoteplase, or DSPA, in their saliva that thins victims’ blood and helps it flow more freely. The good news for the rest of us is that DSPA may also be used to break up the blood clots in the brain that cause stroke.

About 87% of the 795,000 strokes that affect Americans each year are known as ischemic strokes. They are caused by blood clots that clog blood vessels in the brain, blocking adequate blood and oxygen flow and resulting in tissue death. That in turn causes lasting effects like paralysis, cognitive deficits and speech problems. (The other type of stroke, caused by a ruptured blood vessel that bleeds, is called a hemorrhagic stroke and carries a much higher death rate.)

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Time is of the essence when it comes to ischemic stroke treatment: a type of blood-clot “buster” called tissue plasminogen activator (tPA) must be administered within three hours of stroke, after which time its harms (risk of brain damage) outweigh its benefits. Since most stroke patients don’t seek care fast enough, tPA is used in a very small percentage of sufferers.

That’s where DSPA in vampire bat saliva comes in. Reporting in the journal Stroke: Journal of the American Heart Association, researchers compared the effect of DSPA to that of a recombinant form of tPA (called rt-PA), and found that DSPA may not only work as well, but could help patients who wait longer to seek treatment.

Reported Scientific American:

Previous research had shown that DSPA is more active than the currently FDA-approved clog-busting drug rt-PA when exposed to fibrin (an insoluble protein that makes up the framework of blood clots). … To test DSPA’s effect on brain cells, Robert L. Medcalf of Monash University in Australia and his colleagues injected the brains of mice with both DSPA and rt-PA. They found that DSPA attacked fibrin, but did not act upon two brain receptors known to promote brain damage. The scientists therefore suggest that DSPA could be administered up to nine hours after stroke onset without adverse effects.

DSPA was first discovered in 2003, but doctors are only now in the process of developing a drug from it (it’s called — no joke — Draculin). The first human study of the compound, conducted in 2006 at Ohio State University Medical Center, showed that the medication was safe and well tolerated by recipients. Now a new national study, currently taking place at the same center, will determine whether the drug has any clinical benefit in stroke patients.

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“Time is brain,” said Ohio State’s Dr. Michel Torbey, who is leading the research, in a statement. “We would like to offer an option to our patients at any time they come in after a stroke. Unfortunately, the longer it takes for them to come, the less options are available, because the damage has already occurred in the brain.”