Stem Cells May Help Restore Learning and Memory Function in Brain Cancer Patients

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Human neural stem cells may be capable of helping people regain learning and memory abilities lost as a consequence of radiation treatment for brain tumors, according to a new study.

UC Irvine researchers conducted experiments with rats and found that stem cells transplanted two days after cranial radiation treatments restored cognitive function, and the effects continued for up to four months afterward.

In contrast, rats that were not treated with stem cells showed no cognitive improvements.

“Our findings provide solid evidence that such cells can be used to reverse radiation-induced damage of healthy tissue in the brain,” said Charles Limoli, a UCI radiation oncology professor.

Currently, radiation therapy for brain tumors is limited by how well the brain tissue in surrounding areas can tolerate it.  Patients who receive radiation at effective levels typically suffer varying degrees of learning and memory loss.

“In almost every instance, people experience severe cognitive impairment that’s progressive and debilitating,” Limoli said. “Pediatric cancer patients can experience a drop of up to three IQ points per year.”

In the study, the scientists transplanted multipotent human neural stem cells into the brains of rats that had undergone radiation treatment.  The cells migrated throughout the hippocampus, which is responsible for the growth of new neurons, and developed into brain cells.

Two assessments at one and four months after transplantation showed that the treated rats had enhanced learning and memory abilities.

Only 100,000 human neural stem cells were needed to improve cognition after radiation treatment, the researchers said.  Of the cells that survived, 15 percent turned into neurons and 45 percent became astrocytes and oligodendrocytes — cells that support cerebral neurons.

Meanwhile, 11 percent exhibited a behaviorally induced marker of learning, which indicates the cells had been functionally integrated into the memory circuits of the brain.

“This research suggests that stem cell therapies may one day be implemented in the clinic to provide relief to patients suffering from cognitive impairments incurred as a result of their cancer treatments,” Limoli said.

The study was published in Cancer Research, a journal of the American Association for Cancer Research.