Study Suggests Neural Stem Cells May Regenerate After Radiation Therapy


Key Points

  • The study revealed that neural stem cells within the irradiated subventricular zone of the brain generated new cells, which then incorporated into the demyelinated area where new myelin was being produced.
  • The discovery may have implications for patients with brain cancer and progressive neurologic diseases.
  • Neural stem cells have also been linked to brain tumor development, and the findings could explain why glioblastoma is so hard to treat with radiation.

Scientists have long believed that healthy brain cells, once damaged by radiation designed to kill brain tumors, cannot regenerate. But new research in mice suggests that neural stem cells, the body's source of new brain cells, are resistant to radiation, and can be roused from a hibernation-like state to reproduce and generate new cells able to migrate, replace injured cells, and potentially restore lost function. The study was published online in the journal Stem Cells.

"Despite being hit hard by radiation, it turns out that neural stem cells are like the special forces, on standby waiting to be activated," said lead author Alfredo Quiñones-Hinojosa, MD, a Professor of Neurosurgery at the Johns Hopkins University School of Medicine. "Now we might figure out how to unleash the potential of these stem cells to repair human brain damage."

The findings, he added, may have implications not only for patients with brain cancer, but also for people with progressive neurologic diseases such as multiple sclerosis and Parkinson's disease.

Study Details

In the study, Dr. Quiñones-Hinojosa and colleagues examined the impact of radiation on mouse neural stem cells by testing the rodents' responses to a subsequent brain injury. To do the experiment, the researchers used a device invented at Johns Hopkins that accurately simulates localized radiation used in human cancer therapy. Other techniques use too much radiation to precisely mimic the clinical experience of brain cancer patients, the researchers said.

In the weeks after radiation, the researchers injected the mice with lysolecithin, a substance that caused brain damage by inducing a demyelinating brain lesion, much like that present in multiple sclerosis. They found that neural stem cells within the irradiated subventricular zone of the brain generated new cells, which rushed to the damaged site to rescue newly injured cells. A month later, the new cells had incorporated into the demyelinated area where new myelin, the protein insulation that protects nerves, was being produced.

Findings May Explain Glioblastoma’s Resistance to Radiation

"These mice have brain damage, but that doesn't mean it's irreparable," Dr. Quiñones-Hinojosa said. "This research is like detective work. We're putting a lot of different clues together. This is another tiny piece of the puzzle. The brain has some innate capabilities to regenerate, and we hope there is a way to take advantage of them.” If the researchers are able to unlock this potential in humans, it may help patients recover from radiation therapy, strokes, and brain trauma, he said.

However, Dr. Quiñones-Hinojosa cautioned that the findings may not all be good news. Neural stem cells have been linked to brain tumor development, he noted, and the radiation resistance his experiments uncovered could explain why glioblastoma, the most aggressive form of brain cancer, is so hard to treat with radiation.

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.