Human stem cells transplanted into mice with paralysis and demyelination yielded a significant functional improvement — and that research is getting a lot of attention regarding its possible link to treating or even curing multiple sclerosis.
Scientists from the University of California, Irvine; the Scripps Research Institute (La Jolla, Calif.); the University of Colorado, Aurora; and the University of Utah, Salt Lake City, reported their findings in Stem Cell Reports’ June 3 edition.
Recreating Symptoms of Multiple Sclerosis
Mice in the study were first injected with a strain of mouse hepatitis virus known as JHMV to induce paralysis in their hind limbs, demyelination and neuroinflammation, the Stem Cell Reports paper said. These symptoms were meant to mimic the symptoms of multiple sclerosis (MS) in humans. The mice in the study had functional immune systems.
Regaining Function Despite Stem Cell Death
Human stem cells were then injected into the spinal cords of the mice with JHMV disease, and researchers reported “a reduction in the severity of clinical disease, and improved motor skills that were sustained out to six months post-transplantation.”
Researchers said 73 percent of the mice given the stem-cell injections showed functional improvement compared to 14 percent of mice in the control group who improved.
Improvements were seen among the mice given injections containing live cells into their spinal cords. Using dead stem cells or using another delivery method, such as an intravenous one, did not result in improvements.
Researchers said that since the mice had working immune systems, they expected the mice to eventually reject the human stem cells — but researchers were interested in what would happen to the stem cells in the mean time. They found the stem cells “did not migrate extensively within the spinal cord and did not disseminate into peripheral tissues.”
The stem cells died about a week after transplantation.
Nonetheless, significant functional gains were seen in the mice; other media outlets reported the mice regained the ability to walk. When researchers studied spinal cord sections from the mice that showed improvement, they found the spinal cords displayed “a dramatic reduction in the severity of demyelination when compared to control mice.”
Researchers say the improvements such as reduced neuroinflammation are “correlated with an increased number of regulatory T cells (Tregs) within the spinal cords” — cells that modulate the immune system.
“The transient presence of [stem cells] transplanted in an animal model of MS has powerful immunomodulatory effects and mediates recovery,” the researchers said. “Further investigation of the restorative effects of [stem cell] transplantation may aid in the development of clinically relevant MS treatments.”
