Nuclear power offers an efficient, reliable way to provide energy to large populations—as long as all goes well. Accidents involving nuclear reactors such as those that took place in 1986 at Chernobyl and at Fukushima Daiichi after the March 2011 tsunami raise major concerns about what happens if the worst occurs and large numbers of people are simultaneously exposed to high levels of radiation. Currently, there are no effective, safe therapies for total body irradiation (TBI)—a condition known as acute radiation syndrome (ARS). That could change, in the future based on new research published in STEM CELLS Translational Medicine.