Oct. 10, 2012 -- New research suggests that stem cell transplants to treat certain brain and nervous system diseases such as multiple sclerosis may be moving closer to reality.
One study found that experimental stem cell transplants are safe and possibly effective in children with a rare genetic brain disease. Another study in mice showed that these cells are capable of transforming into, and functioning as, the healthy cell type. The stem cells used in the two studies were developed by study sponsor StemCells, Inc.
Both papers appear online in Science Translational Research.
The work, while still in its infancy, may have far-reaching implications for the treatment of many more common diseases that affect the brain and nervous system.
Researchers out of the University of California, San Francisco (UCSF), looked at the how neural stem cells behaved when transplanted into the brains of four young children with an early-onset, fatal form of Pelizaeus-Merzbacher disease (PMD).
Can Stem Cell Transplants Help Treat MS?
PMD is a very rare genetic disorder in which brain cells called oligodendrocytes can’t make myelin. Myelin is a fatty substance that insulates the nerve fibers of the brain, spinal cord, and optic nerves (central nervous system), and is essential for transmission of nerve signals so that the nervous system can function properly.
In multiple sclerosis, the myelin surrounding the nerve is targeted and damaged by the body’s immune system.
The new study found that the neural stem cell transplants were safe. What’s more, brain scans showed that the implanted cells seem to be doing what is expected of them -- i.e. making myelin.
Researchers compared treated areas of participants' brains with untreated areas. "The study goes beyond safety and we see some effects in the transplanted region that are consistent with the appearance of myelin, at one year,” says study author David H. Rowitch, MD, PhD. “It is not definitive, but it is suggestive.” He is a professor of pediatrics and neurological surgery at UCSF, and is the chief of neonatology at UCSF Benioff Children’s Hospital.
PMD is rare, but other diseases that affect the myelin, such as MS, are more common.
So is it possible that these same stem cell transplants could also benefit these other diseases? Although the possibility exists, Rowitch is noncommittal at this point. “We don’t have data that this could work in MS or other diseases,” he says.
With PMD, the cells that produce myelin are not doing their job. Other diseases involve multiple causes or pathways. If further research in treating PMD pans out, the next step will be to look at MS and other diseases that affect myelin, Rowitch says.
Nancy L. Sicotte, MD, is the director of the Multiple Sclerosis Program at Cedars-Sinai Medical Center in Los Angeles. She says that MS may be more complicated to treat with stem cell therapy.
“With MS, we would be trying to introduce stem cells into an inflamed nervous system,” she says. "To be effective, we have to stop the inflammation process, which we haven’t fully been able to do yet.”
Still, “stem-cell based therapies hold a lot of promise and potential,” Sicotte says. “You always have to temper that with the fact that it takes time to bring a great idea in the lab to humans.”
A Big Deal
A related study by researchers at Oregon Health & Science University's (OHSU) Doernbecher Children’s Hospital in Portland showed that banked brain stem cells can survive and make myelin in mice with symptoms of myelin loss. This work served as one of the building blocks for the study in children with PMD.
This mouse study also gives scientists a glimpse into how these cells behave once they are transplanted, says researcher Stephen A. Back, MD, PhD. He is a clinician-scientist in the Papé Family Pediatric Research Institute at OHSU Doernbecher. “When implanted, they preferentially make myelin-forming cell.”
This is a big deal.
“Stem cells are capable of making new myelin in a brain showing deterioration, and that is very exciting,” he says. “We were surprised to see how well the new myelin was able to form in symptomatic animals.”
The implications are far-reaching. For example, “if we show in a rare disorder like PMD that patients benefit from the transplants, then we will want to do newborn screening to pick up babies with the disorders and get them transplanted as soon as possible,” Back says. “The sooner you get to these kids, the better, [since] the disease can progress like gangbusters once it starts.”