A trial involving researchers at the University of Colorado found it can be safe to transplant stem cells into the brains of people with at least one disabling illness, but the science has a long way to go before people heal with cells from embryos or their own bodies.
The trial, involving scientists in Colorado, the United Kingdom and Italy, infused stem cells taken from the brain of a fetus that had died in a miscarriage into 15 Italian patients who already had significant disabilities caused by multiple sclerosis. In the year after the infusions, the patients’ multiple sclerosis didn’t get worse, and they didn’t have severe side effects from the stem cells.
It will take a bigger trial with a comparison group that didn’t receive the treatment to know whether the stem cells truly slowed down the disease’s progression, though, said Angelo D’Alessandro, a professor at CU’s Anschutz Medical Campus.
“The disease was overall stable,” he said.
In multiple sclerosis, the immune system attacks a substance called myelin that coats cells in the nervous system. As the myelin wears away, the nerve cells lose the ability to communicate with each other, gradually leading to problems with walking and other daily tasks, Alessandro said.
Some people’s illnesses progress much faster than others’, and not everyone has all of the symptoms, which can include vision problems, muscle weakness, pain or loss of sensation, fatigue and difficulty speaking.
Scientists have talked about stem cells as a possible solution to degenerative diseases like multiple sclerosis for decades, because while medication can prevent dramatic flare-ups of the disease, there’s no way to stop gradual loss of function over time, said Dr. Michael Sy, a neurologist at the University of California Irvine.
This particular study showed that infusing stem cells into the brain can be done safely, but didn’t suggest patients could expect dramatic improvement from these types of transplants any time soon, he said.
Commercialization of stem cell technology has gotten well ahead of science, though.
The only approved treatments using stem cells are bone marrow transplants, but in 2021, researchers found more than 2,700 clinics operated in the United States, offering to use embryonic stem cells or cells from patients’ own fat to treat a variety of diseases. Some patients have gone blind or developed tumors after receiving stem cell injections.
At the beginning of human development, stem cells could form any type of cell in the body, but they gradually take on specialties. The donated cells in the multiple sclerosis trial could only become brain tissue at that point, reducing the odds they’d develop into tumors.
Previous studies in rodents and non-human primates engineered to have a disease like multiple sclerosis found that the transplanted cells went to the parts of their brains that had lesions and appeared to partially repair them, Alessandro said. It’s not clear if the same thing would happen in humans, but those that received larger doses in the trial had more significant changes in the fluid surrounding their brains and spines that suggested their cells were healthier, he said.
It’s possible that a small percentage of the stem cells converted into cells in the brain, replacing damaged ones, Alessandro said. Stem cells can also give their mitochondria — the powerhouses of cells — to the existing neurons, which could reduce inflammation in the brain, he said.
All of the 15 patients in the trial were middle-aged and had advanced forms of multiple sclerosis, with significant disability. Even if subsequent trials find a benefit for that group, it’s not clear if different types of patients would find it helpful.
Stem cell transplants likely wouldn’t be a first line of treatment. To deliver the cells into the brain, doctors had to cut a hole in the patient’s skull, a process that comes with the risk of injury or introducing an infection.
It’s possible that this approach won’t pan out, but even in that case, it might advance the field for others to try something else, Alessandro said. The researchers are planning a second trial to quantify if the stem cells produced benefits, but aren’t enrolling patients in Colorado at this point.
“This can give hope to patients,” he said.
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