In a result defying popular opinion, the human heart regenerates about half of its cells over the course of a normal lifespan, the New York Times reports. A study used levels of a radioactive isotope in the earth’s atmosphere released by aboveground nuclear tests, and found in our bodies, to gauge turnover. Cells damaged in heart attack do not regenerate, and scientists hope the discovery might lead to new drug therapies.
“I think this will be one of the most important papers in cardiovascular medicine in years,” one heart researcher said. “It helps settle a longstanding controversy about whether the human heart has any ability to regenerate itself. I was really impressed at the level of rigor they put into this analysis.”