Stem Cell Treatment for Stroke: Proven Safe and Effective

Stroke remains a primary cause of disability in North America, leading to significant neurological impairments and a decrease in quality of life. Each year, strokes are responsible for over 140,000 deaths in the United States, leaving many survivors with enduring neurological challenges that affect their ability to speak, move, and be self-sufficient. Various therapeutic approaches, including physiotherapy, mobility training, and exercises aimed at enhancing motor skills and range of motion, are employed to aid recovery by improving neural function, mobility, and behavior.

Mesenchymal Stem Cells in Stroke Recovery

A groundbreaking study by Michael Levy and his team presents intravenous allogeneic mesenchymal stem cell injections as a safe and promising treatment for long-term recovery after a stroke.

Published by the University of California, this placebo-controlled, randomized study involved 36 individuals who had suffered an ischemic stroke more than six months prior to enrollment. Eligibility for the study was based on the lack of significant neurological or functional improvement for at least two months before joining the study.

The study was conducted in two phases, with each phase escalating the dose of cells based on the safety findings of the previous phase. The highest dose administered was 150 million mesenchymal stem cells, following initial safety confirmation with a dose of 1.5 million cells/kg of body weight. Quality control tests were performed on the cell bank, including assessments of cell count, viability, appearance, and the absence of viruses.

According to Michael Levy and colleagues:

"The primary study endpoint was safety and tolerability, evaluated in all subjects who received any portion of an infusion, and determined by the incidence/severity of adverse events, clinically significant changes on laboratory and imaging tests, vital signs, and physical plus neurological examinations. Four secondary endpoints were scored serially to derive preliminary estimates of efficacy: National Institutes of Health Stroke Scale, Barthel Index (BI), Mini-Mental Status Exam, and Geriatric Depression Scale. For each, the change from baseline was evaluated using Wilcoxon signed-rank test, with primary analysis of preliminary efficacy being change from baseline to 6 months post-infusion, and analysis including all subjects who received an infusion except for one subject who failed to return after the day 10 visit for all visits (except for month 9 follow-up)." 

Safety and Efficacy

The study confirmed the safety of this treatment, with no adverse reactions to intradermal tests (allergy tests) or significant findings in follow-up physical exams and blood tests. Statistically significant improvements were noted in participants' Barthel scores—a metric for daily living activities—rising from an 11.4% baseline improvement to 35.5% at 12 months post-treatment. These results suggest that mesenchymal stem cells are not only safe but also potentially effective in enhancing function post-stroke.

Subject behavioral improvements: 

"Across all subjects, improvements were seen in National Institutes of Health Stroke Scale, BI, Mini-Mental Status Exam, and Geriatric Depression Scale scores at both the 6-month and the 12-month follow-up visits." 

"Intravenous infusion of MSC was found to be safe in 36 patients who had chronic stroke with substantial functional deficits. Across 3 escalating doses, treatment-related adverse events were infrequent, mild, and transient. Serial assessments of exam, laboratory testing, electrocardiogram, and CT scans of chest/abdomen/pelvis disclosed no safety concerns, with limited subject dropout. These results are consistent with the overall excellent safety record that MSC has in clinical trials of human subjects across numerous non-cerebrovascular diagnoses 15, 24–27 and in stroke trials." 

This investigation, the most extensive of its kind to assess intravenous MSCs in chronic stroke patients, found that, contrary to the typical functional decline seen in chronic stroke patients, those treated with MSCs showed functional improvements over 12 months. The study underscores the enduring impact of MSCs on brain function even a year after treatment. Levy and his colleagues suggest that combining MSC treatment with functional restorative therapies could maximize cognitive benefits, offering a holistic approach to stroke recovery beyond MSC infusion alone.

Reference: 

• Levy, Michael L., et al. “Phase I/II Study of Safety and Preliminary Efficacy of Intravenous Allogeneic Mesenchymal Stem Cells in Chronic Stroke.” Stroke, vol. 50, no. 10, 2019, pp. 2835–2841., doi:10.1161/strokeaha.119.026318.