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Stroke recovery may be boosted by new drug, animal study shows

Two mice in stroke therapy experiments as they try to reach a small object
Two mice reach for a pinpoint object after receiving a therapeutic drug post-stroke. Photo: H. Abe et al., Science (2018)

A new drug compound can successfully speed up rehabilitation for animals recovering from stroke, according to research published in Science Thursday. If it works in humans, it could eventually extend the time for repairing some brain functions after injury.

The big picture: An estimated 1.7 million people suffer a traumatic brain injury in the U.S. every year and almost 800,000 of those are from a stroke. Strokes kill 140,000 people per year and are the leading cause of serious long-term disability, CDC says.

Background: A stroke happens when brain cells die because the blood supply is interrupted by a clot, or a blood vessel bursts from high blood pressure or an aneurysm. Within minutes, neurons are permanently damaged and they die and leave a "hole" in the brain. Not only is that specific area damaged but surrounding neurons can also be injured.

Acute therapy during those first few hours is key, but scientists are also looking for ways to boost the brain's plasticity in the days or months following a stroke. The study out today looks at one possibility: giving a compound that enhances motor function recovery when combined with rehabilitation therapy.

What they did: The team gave mice the compound edonerpic maleate orally one day after a stroke and started rehab three weeks later (imagine a mouse reaching for a small object). After they received positive results, the researchers conducted a similar experiment in monkeys. (Note: Some of the study authors include employees of Toyama Chemical Co., which owns rights to the edonerpic maleate compound and also helped fund the part of the experiment involving monkeys.)

What they found: The key to faster recovery was the three-part-combo — introduce the compound as soon as possible after the stroke, check that it binds to a specific protein called CRMP2, and begin rehab as soon as possible.

  • Study author Takuya Takahashi from the Yokohama City University in Japan tells Axios the treatment continued to work even a month later. Here is a video from their experiment.

Timing is key:  "We believe there is a 'window of time' (about 3 months) for plasticity to allow motor recovery, "Argye Elizabeth Hillis, neurology professor at Johns Hopkins University School of Medicine, tells Axios.

"[It's] essential. Most recovery takes place through synaptic plasticity, so medications that enhance plasticity are likely to benefit. People currently recover to varying degrees, but stroke remains one of the most common causes of disability in adults."

Yes, but: The efficacy of the drug has not yet been tested in humans. Tadashi Isa from Kyoto University's School of Medicine says human testing will likely face challenges, including the fragility of the patients and possible side effects such as epilepsy.

What's next: Takahashi says they plan to start human clinical trials by early 2019.

Another approach: Institut für Physiologie's Simon Rumpel, who wrote an accompanying Perspective, tells Axios another therapy being tested now involves injecting stem cells into damaged tissue. However, he says this new study is "promising" because it is "targeting the core mechanism by which spontaneous recovery from brain damage is believed to occur."