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Natural Chemical May Treat Strokes

Natural Chemical May Treat Strokes
WebMD Health News
Reviewed by Gary D. Vogin, MD

June 24, 2002 -- A naturally occurring chemical that stimulates nerve growth may one day help stroke patients recover. Testing in humans could begin early next year for inosine, which appears to help the brain "rewire" itself after injury.

If those trials prove successful, inosine could represent a major advance over existing treatments, researchers say, because it can be given up to 24 hours after a stroke. Current therapies must be given within two to three hours, and fewer than 10% of stroke patients are treated during this window.

In newly reported studies involving rats, inosine was shown to promote the growth of nerve cells in areas of the brain that remained undamaged following stroke. This new nerve growth, in turn, took over some of the functions of the stroke-damaged parts of the brain. The findings are reported in the June 25 issue of the Proceedings of the National Academy of Sciences.

"At least in principle, we have shown that inosine can greatly stimulate the rewiring of the brain," says lead investigator Larry I. Benowitz, PhD, of Harvard Medical School. "In stroke there is a loss of brain circuitry. If we can prompt compensatory growth from the remaining intact nerve fibers, that could be very beneficial."

Benowitz and colleagues injected inosine into the brains of rats with experimentally induced strokes. Following recovery, the treated rats showed dramatic improvement in physical performance over rats given placebo treatments.

In one experiment, the animals were trained to reach through the bars of a cage to get food pellets placed just outside. By the fourth week of the study, half of the inosine-treated rats used their stroke-affected paws to reach for food, while none of the placebo treated rats did.

"This is a totally novel approach to treatment that suggests we can repair the brain after injury," says National Stroke Association spokesman Lawrence Brass, MD. "This is one of the first studies to provide evidence that this can happen, that it can happen in mammals, and that it can happen in a way that translates into behavioral improvement." Brass is a professor of neurology at Yale University School of Medicine.

Benowitz has spent years researching how nerve cells form their connections. His work with fish, which are able to spontaneously regenerate brain pathways, led to the discovery that inosine stimulates the formation of nerve cell connections.

"This compensatory nerve growth occurs normally after a stroke, but it is to a much lesser degree than we have seen with inosine," Benowitz tells WebMD, adding that nerve growth with the drug was approximately four times greater than normal.

The first human trials of inosine will involve about 20 patients with severe strokes, says Marc Lanser, MD. Lanser is founder and chief scientific officer for Boston Life Sciences Inc., which holds the licensing agreement for the treatment. Patients will be given infusions under local anesthesia within 24 hours of their strokes. If all goes well, Lanser says, the new treatment could be commercially available within three years.

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