Therapy Worked. But How?
Stem cell injections relieve stroke patients in a pilot trial.
Excitement tempered by wariness will spur a new stage of surgical trials by Stanford researchers hoping to reverse long-term disabilities caused by stroke. The catalyst is a very small and limited study that nevertheless made vivid news because of the dramatic improvements experienced by some patients.
In pilot clinical trials conducted at Stanford and at the University of Pittsburgh Medical Center, 18 stroke victims were treated by having modified human stem cells — derived from the bone marrow of adult donors — injected near the damaged areas of their brains with a syringe inserted through a hole drilled in their skulls. Twelve months later, says Professor Gary K. Steinberg, chair of the School of Medicine’s neurosurgery department and the study’s lead author, half of the patients were experiencing “improvement that changed their lives in a meaningful way.”
The enduring nature of the improvements is one hallmark, but the immediacy and magnitude of the benefits for some participants led Steinberg, PhD ’79, MD ’80, to describe them as “miracle patients.” Two years after a stroke, Sonia Olea Coontz couldn’t raise her right arm, and her speech was too impaired to be readily understood. But the day after the stem cell implantation, she could lift her arm over her head, extend it out to the side and then back across her body — all shown in a Stanford video in which Coontz also recounts being able to speak far more fluently as soon as she was conscious after the procedure.
The recoveries that occurred for Coontz and other patients triggered the attention of media and numerous people nationwide with impediments caused by strokes. But drawing conclusions from the small trial, designed primarily as a safety and feasibility study, is premature, Steinberg and other experts note. Plans have been made for a second stage of controlled trials with more than 150 patients.
“There are many examples of therapies in (central nervous system) diseases that have had a seemingly important effect in an early, small trial and then not been validated in larger trials,” says Professor S. Thomas Carmichael, vice chair for research and programs in neurology at UCLA’s school of medicine.
Carmichael adds, however, that the study helps refute a widely asserted notion that stroke patients suffering from persistent disability have lost the possibility of recovering. It’s the idea that by “six months out, you’re done.” Rehabilitation exercises have demonstrated that “you can get better,” says Carmichael, and the Stanford experiment produced “two to three times more improvement” than any previous approach.
Steinberg has been working on stem cell treatments for stroke for 15 years; the cells for this research were created by SanBio, a company in Mountain View. But it’s unknown what part, if any, the cells played in the recoveries. Another explanation might be that the body has regenerative potential that was stimulated by some aspect of the procedure. Steinberg feels certain there’s not a placebo effect — changes based on a psychological boost, not a physiological impetus — because the improvements are “much too substantial and unprecedented in chronic stroke patients” for that.
The next trials will be randomized, with patients assigned by chance to groups that do or don’t receive the experimental treatment, as well as double-blind, which means neither the researchers nor the participants will know who’s in which group. •