Transplanting human stem cells into the spinal cord of people with amyotrophic lateral sclerosis (ALS) may be safely accomplished, according to the results of a Phase 2 clinical trial. The study, led by researchers at the Emory University School of Medicine and the Nell Hodgson Woodruff School of Nursing in Atlanta, was not designed to assess the efficacy of the treatment, but results suggest it did not accelerate the progression of the disease.
The findings were published in the journal Neurology in a study titled “Transplantation of spinal cord-derived neural stem cells for ALS.”
There are currently no treatments that prevent the progression of ALS. Stem cells have been proposed as a potential therapy for ALS based on their ability to self-renew and differentiate into multiple cell types, which may help repairing or replacing the injured cells.
“Though there were two serious complications related to the treatment, the level of acceptable risk for treating patients with ALS, where the prognosis is poor and treatments are limited, is arguably higher than that for more benign disorders,” said Jonathan D. Glass, M.D., a professor of neurology at Emory University School of Medicine in Atlanta and a member of the American Academy of Neurology, in a press release.
The open-label Phase 2 trial enrolled 15 participants with ALS at three academic centers who had their first symptoms within two years of the start of the study. The patients were divided into five treatment groups, receiving increasing doses of stem cells by increasing the number of injections, which ranged from 10 to 40, and the number of stem cells per injection, which ranged from 2 million to 16 million cells.
All participants received bilateral injections into the cervical spinal cord between the C3 and C5 regions, and the final group received injections into the lumbar cervical cord, between the L2 and L4 regions, in two separate surgeries. During the nine months of follow-up, patients were assessed for adverse therapy effects. Disease progression was also evaluated through the ALS Functional Rating Scale–Revised, forced vital capacity, and quantitative measures of strength.
Researchers found that most of the adverse effects were related to the transient pain associated with the surgery and to the medications that suppress the immune system. Suppressing the immune system in these patients is required to keep the immune cells from recognizing the transplanted stem cells as foreign and attacking them.
Two patients developed serious complications associated with the treatment. One developed spinal cord swelling, which caused pain and partial paralysis; the other exhibited central pain syndrome, most likely due to damage to the spinal cord.
The researchers compared patients’ outcomes with those from three separate historical control groups, revealing that the stem cell treatment did not change the rate of progression. However, Glass warns that this study is not big enough to draw conclusions about the treatment efficacy.
“This study was not designed, nor was it large enough, to determine the effectiveness of slowing or stopping the progression of ALS. The importance of this study is that it will allow us to move forward to a larger trial specifically designed to test whether transplantation of human stem cells into the spinal cord will be a positive treatment for patients with ALS,” Glass said.