Heart disease is one of the world’s most deadly and insidious killers. In the United States alone, it causes one in every four deaths nationwide—that’s a staggering 659,000 people each year, or roughly equivalent to the entire population of Portland, Ore.
It’s perhaps not surprising that the heart is so vulnerable to damage. It’s arguably the hardest working tissue in the human body: one of the first organs to form in the womb, it must keep ticking, without end, for the rest of our lives. Astoundingly, though, the cells within it can’t easily divide and reproduce. If damage occurs to any of them, that’s it—the injured region of tissue won’t be able to repair itself. Instead, the undamaged parts of the organ will limp along as best as they can until the bitter end.
