A small group of patients with stable, chronic stroke who had stem cells injected in their brains had a significant improvement in neurological function in the 12 months after treatment, according to an open-label, single-arm study.

Lead researcher Gary K. Steinberg, MD, PhD, of Stanford University’s School of Medicine, and colleagues published their results online in Stroke on June 2. SanBio Inc., which is developing the SB623 treatment for stroke, funded the study.

“This was just a single trial, and a small one,” Steinberg said in a news release. “It was designed primarily to test the procedure’s safety. But patients improved by several standard measures, and their improvement was not only statistically significant, but clinically meaningful. Their ability to move around has recovered visibly. That’s unprecedented. At six months out from a stroke, you don't expect to see any further recovery.”

This phase 1/2a study included 18 patients with chronic motor deficits who sustained a nonhemorrhagic stroke between six and 60 months before enrollment. The mean age was 61 years old, and 61 percent of patients were female.

The researchers enrolled patients at Stanford University and the University of Pittsburgh Medical Center between September 2011 and August 2013. During the study, the patients did not receive poststroke rehabilitation.

The patients were divided into three cohorts and all received single doses of SB623 cells, which are modified bone marrow–derived mesenchymal stem cells. They were developed as an allogeneic cell therapy for chronic motor deficit because of stable stroke, according to the researchers.

Each of the patients had at least one treatment-emergent adverse events, while six patients had six serious treatment-emergent adverse events, although none were related to cell treatment.

The most frequently reported treatment-emergent adverse events were headache related to surgical procedure (77.8 percent of patients), nausea (33.3 percent), vomiting (22.2 percent), depression (22.2 percent), muscle spasticity (22.2 percent), fatigue (16.7 percent), blood glucose increase (16.7 percent) and C-reactive protein increase (16.7 percent).

The researchers said each of the serious treatment-emergent adverse events were resolved without sequelae. There were also no dose-limiting toxicities or deaths.

After 12 months, 16 patients had completed the follow-up. There was a significant improvement from baseline for European Stroke Scale, National Institutes of Health Stroke Scale, Fugl-Meyer total score and Fugl-Meyer motor function total score.

“Despite stroke representing a major cause of mortality and severe disability, the only proven therapies for ischemic stroke are intravenous tissue-type plasminogen activator and intra-arterial thrombectomy, both of which must be administered within a few hours of stroke onset,” the researchers wrote. “Currently, there are no proven medical or surgical neurorestorative treatments available for subacute or chronic stroke. However, stem cell and cultured cell therapy for chronic stroke is moving quickly into the clinical arena.”

The researchers cited a few limitations of the study, including the small number of patients and its nonrandomized design. They also had a highly selective patient screening process and only enrolled 4.7 percent of screened patients. In addition, their definition of stable chronic stroke was used in some trials, although other studies have had different definitions. Still, the researchers were encouraged with the findings.

“This wasn’t just, ‘They couldn’t move their thumb, and now they can,’” Steinberg said. “Patients who were in wheelchairs are walking now. We know these cells don’t survive for more than a month or so in the brain. Yet we see that patients’ recovery is sustained for greater than one year and, in some cases now, more than two years.”