Not long afterward, the stem cells that built the heart dwindle until they almost disappear. And later—decades after the builders have gone—the house itself begins to fall apart. Arteries clog with plaque, plaque causes heart attacks, heart attacks destroy ventricular muscle. In the worst cases, the damage is so great that the only option is a transplant.
Over the next decade, though, many stem cell researchers believe, doctors will be able to restore even "irreversibly" damaged hearts, at least in part. "The ability to replace dead heart muscle with new lab-grown muscle after a heart attack is one of the great goals in medicine today," says Deepak Srivastava, MD, director of the Gladstone Institute of Cardiovascular Disease in San Francisco. If scientists can manage to do so, it would be monumental. Cardiovascular disease affects an estimated 81 million Americans and is the leading cause of death for both women and men in the United States.
The leap forward has been driven by a series of startling breakthroughs. Among the most radical was the discovery, in 2007, of a way to transform ordinary human adult skin cells back into stem cells (known as induced pluripotent stem cells, or IPS cells), by manipulating a small piece of the genetic code. IPS cells can be chemically prodded to become almost any tissue, including bone, cartilage, or heart. And they neatly sidestep the political and ethical morass surrounding embryonic stem cells—which, unlike IPS cells, must be derived from human embryos left over from fertility treatments.
How this could open the door to new heart treatments