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Stanford University School of Medicine

Stroke of luck: Stem-cell transplants show strong signs of efficacy in clinical safety trial for stroke

stroke-soniaSonia Olea Coontz, pictured here, suffered a stroke in 2011 that left her limping. Now, thanks to an experimental procedure she underwent in 2013 -- a full two years later -- she's jogging.

Virtually all recovery from a stroke occurs within the first six months after the event. That leaves close to 7 million stroke survivors in the United States alone whose condition is chronic: They're just stuck for the rest of their lives with disabilities that vary depending on exactly where in the brain the stroke was and on its severity.

But a recently concluded clinical trial suggests that dramatic improvements are possible, even years after a stroke has occurred. In this early-phase trial, led by Stanford neurosurgeon Gary Steinberg, MD, PhD, and described in a paper published in Stroke, stem cells were injected directly into patients' brains, close to where the stroke had taken place. Note: These were not embryonic or fetal stem cells but a variety of adult cells called mesenchymal stem cells, which are the naturally occurring precursors of muscle, fat, bone and tendon.

These cells have a number of selling points. They're easily harvested from bone marrow. Preclinical research has indicated they don't cause problems by differentiating into unwanted tissues or forming tumors. And even when they come from an unrelated donor -- as was the case in this trial -- they not only appear to trigger no dangerous immune reaction in recipients but may actively suppress the immune system.

The cells, as genetically modified in culture before their use in the trial, are the intellectual property of SanBio, Inc., a biotechnology company based in Menlo Park, Calif.

The investigators screened 379 patients and selected 18, average age 61, who'd sustained a substantial stroke beneath the outer layer, or cortex, of the brain. For most patients, at least a full year had passed since their stroke -- well past the time when further recovery might be hoped for. From our news release:

The patients, all of whom had suffered their first and only stroke between six months and three years before receiving the injections, remained conscious under light anesthesia throughout the procedure, which involved drilling a small hole through their skulls; the next day they all went home. Although more than three-quarters of them suffered from transient headaches afterward -- probably due to the surgical procedure and the physical constraints employed to ensure its precision -- there were no side effects attributable to the stem cells themselves, and no life-threatening adverse effects linked to the procedure used to administer them.

Not only that, but the procedure seems to have concretely benefited patients. Their ability to move formerly disabled or paralyzed limbs, or to speak, improved noticeably and enduringly despite the length of time that had elapsed since their stroke.

"This wasn't just, 'They couldn't move their thumb, and now they can.' Patients who were in wheelchairs are walking now," Steinberg told me. Patients' postoperative improvement was independent of their age or their stroke's severity.

"The notion was that once the brain is injured, it doesn't recover -- you're stuck with it," said Steinberg, who's been actively pursuing stem-cell-based stroke remedies for well over a decade. "But if we can figure out how to jump-start these damaged brain circuits, we can change the whole effect. We thought those brain circuits were dead. And we've learned that they're not."

A substantially scaled-up randomized trial led by Steinberg is now actively recruiting stroke patients; contact information can be found in our release.

Previously: Stanford study: Commonly used sleeping pill may boost stroke recovery, Targeted stimulation of specific brain cells boosts stroke recovery in mice and Brain sponge: Stroke treatment may extend time to prevent brain damage
Photo by Mark Rightmire

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