Human embryonic stem cells could help people with learning and memory deficits after radiation treatment for brain tumors, a new UC Irvine study suggests. Research with rats found that transplanted stem cells restored learning and memory to normal levels four months after radiotherapy. In contrast, irradiated rats that didn’t receive stem cells experienced a more than 50 percent drop in cognitive function. “Our findings provide the first evidence that such cells can be used to ameliorate radiation-induced damage of healthy tissue in the brain,” says Charles Limoli (pictured), UCI radiation oncology associate professor and senior author of the study, which appears in the Nov. 10 issue of the Proceedings of the National Academy of Sciences.