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April 7, 2013

Emergency Stroke Drug

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Millions of Americans are living with the aftermath of having a stroke. A former Miss Arizona talks about her stroke at age 26, and this ScienCentral News video explains how researchers are looking for safer ways to treat strokes when they happen.

Interviewees: Leean Hendrix, Stroke Survivor
Andras Gruber, Oregon Health and Science University
Length: 1 min 38 sec
Produced by Sandy Chase
Edited by Sandy Chase/Charles Young/James Eagan
Copyright © ScienCentral, Inc.
with additional footage courtesy Mayo Clinic,
American Heart Association, ABC News,
and special thanks to Oregon Health and Science University."


Safer Clot-busters?

Leean Hendrix looks fine now, but in 2002, this former Miss Arizona had a stroke that left half her body paralyzed. Lots of hard work recovered most of her movement but nothing can restore her memories. Hendrix wishes she had been given a drug that might have drastically reduced the damage from the stroke

While current clot-busting drugs can make a huge difference in stroke survival and recovery, they are also so risky that doctors hold off giving them until they are absolutely sure a stroke has occurred — which is often too late for people like Hendrix.

"They would have treated me with tPA, which is the clot-busting drug, and I would have virtually walked out of the hospital with no side effects from the stroke. Instead… I went from being a young, healthy, independent 26-year-old to somebody who had to have somebody help her brush her teeth," she says.

image: American Heart Association
780,000 Americans will have a stroke this year. And millions more are living with the aftermath of having one. A stroke results from an interruption in blood flow to part of the brain. About 83 percent of the cases are caused by a blockage in a blood vessel in the brain-- either a clot that has formed there or one has traveled to the brain from another part of the body, and gotten lodged in a blood vessel. The other 17 percent of strokes are caused by a burst blood vessel that causes bleeding in the brain.

Stroke can be fatal or can cause partial paralysis, problems with vision, speech, language, or cognition. In Hendrix's case, she had long-term memory loss that makes much of her high school experience a blank. "I do not remember my first kiss. I do not remember prom. I don't remember playing sports. You know, all those things that kind of help to make you the person you are today… I don't remember them," Says Hendrix.

Current life-saving drugs like tPA and warfarin prevent clotting everywhere in the body and can cause spontaneous bleeding, including in the brain. If given within three hours of the onset of a stroke, they can help break up clots, restore blood flow, and reduce the damage of the stroke. However, after three hours, the risk of the treatments outweigh the benefits, so in fact, less than five percent of people who have a stroke receive the drugs.

Now biomedical researcher Andras Gruber and his colleagues at Oregon Health and Science University have engineered a drug that could be safer. Gruber says, "The blood is supposed to be flowing in the blood vessels and clotting when it gets out of the blood vessels." He calls these "good clots". "Bad clots" are clots that form inside of blood vessels. "The bad clots are clots that cause diseases, actually catastrophic diseases, he says. "Stroke, heart attack, pulmonary embolism, sepsis."

The new drug, WE-Thrombin, is engineered from the natural enzyme called thrombin, which helps form blood clots. The new version attaches to platelets in the blood and is carried around the body through natural circulation.

The researchers reported in the journal Arteriosclerosis, Thrombosis, and Vascular Biology that WE-thrombin is inactive until a bad clot forms. At that point, it interacts with the blood vessel wall to stop clot formation. In animal tests it showed no adverse side effects, in other words, it does not interfere with forming the "good clots" we need for wound healing and keeping the blood from leaking into other tissues.

The role of thrombin is based on work by Enrico Di Cera of Washington University and investigations by Owen McCarty of OHSU.

If it works in people, it could be given at the first sign of a stroke, restoring circulation to the brain minutes or hours earlier than current treatments… fast enough to give stroke victims like Hendrix a future, but without losing their past.

The researchers say the drug could also be an emergency treatment for heart attacks and other conditions caused by clotting, but first it needs to be tested and approved for use in people.

PUBLICATIONS: Arteriosclerosis, Thrombosis, And Vascular Biology, February 2008. Blood, January 2007.

RESEARCH FUNDED BY: American Heart Association and National Institute of Health.

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