Stem cells restore brain functions

Radiation therapy is a powerful and potentially life-saving treatment for primary and metastatic brain tumours and other cancers. However, radiotherapy has serious irreversible side effects, including learning and memory problems and impaired motor skills. These effects can be especially pronounced in children, whose brains are still developing. A new preclinical study published in the current issue of the prestigious journal Cell Stem Cell shows that stem cell-based treatment may reverse the damaging side effects of radiation therapy.

During radiation treatments, the radiation that kills tumour cells also destroys the cells that form an insulating layer, known as myelin, around the nerve fibers of brain cells. Without this myelin sheath, nerve cells can no longer transmit their electrical impulses, leading to neurological problems. In the study, led by senior author Dr. Viviane Tabar, scientists induced human stem cells to transform into the type of cells which make the myelin sheath. The scientists then injected these cells into the brains of rats which had previously received doses of radiation similar to what cancer patients would receive. Behavioral tests showed that the rats which were given the new cells recovered their memory and learning abilities, compared with rats which were irradiated but not given the myelin-forming cells. Furthermore, rats receiving the new cells also recovered from their motor and balance deficits. Cellular imaging showed that the transplanted cells survived and migrated within the rats’ brains, and restored myelin that had been destroyed by radiation treatment.

Brain damage resulting from radiation therapy decreases quality of life for cancer survivors, and is presently untreatable. The current study provides a basis for further translational studies and clinical trials to develop a stem cell-based treatment to address radiation-induced brain damage. Such a treatment could eventually improve patients’ quality of life, while extending the use of radiotherapy to some patients for whom radiation is currently too risky, such as children.