Clinical Trials Are Testing Stem Cells as Heart Failure Treatment

A bounty of trials are exploring the healing potential of injecting stem cells into ailing hearts.


In the hope of rejuvenating his failing heart, Brent Benson, 68, signed up to have his own stem cells injected directly into the deteriorating organ. As part of a clinical trial at the University of Utah in Salt Lake City, stem cells were extracted from bone marrow taken from Benson's hip, processed, and a few weeks later injected into his heart. The 30-some injections targeted areas of his heart that were essentially hibernating—not well-functioning, yet not scarred, as a particularly damaged heart can become after injury.

The ongoing study is one of many clinical trials now testing the ability of heart failure patients' own stem cells—which renew themselves and can develop into a range of cell types—to regenerate heart muscle and restore blood flow inside the heart tissue. Heart failure patients suffer a deficit of both blood flow and functioning heart muscle, which weakens the organ's ability to pump vigorously and ultimately deprives other organs of oxygen they need. "I'm essentially dying of heart failure," says Benson, a trained biochemist who used to conduct tests for the Environmental Protection Agency. "I was so far down, I had to try."

By at least one objective measure, Benson's heart has considerably improved in the nearly five months since his treatment. His ejection fraction, a measure of how well the heart pumps, has gone from about 15 percent back up to over 30 percent, he says. Normal is somewhere between 55 and 70 percent. But Benson measures the gain mostly in his reclaimed ability to do physical labor, especially to tend the fruit trees on his small farm in Benjamin, Utah, and work on the deck at his family's home, which stands above 9,000 feet in elevation. Both previously had been impossible because of the extreme shortness of breath and fatigue characteristic of heart failure. "My life is [now] full and busy," Benson explains. "I had lost that prior to this operation."

Researchers' significant interest in using stem cells to treat heart failure arises, in part, because the disease is so prevalent. The American Heart Association estimates 5.7 million Americans live with the disease and 670,000 new cases are diagnosed annually. "When you put [stem cells] into a heart, some can differentiate to become blood vessel and others to become heart muscle cells," explains James Willerson, president of the Texas Heart Institute in Houston and a principal investigator of a separate, National Institutes of Health-sponsored stem cell trial for heart failure. It is important, he says, that stem cells also "have substances that recruit other cells and promote life." This combination holds incredibly powerful potential for not only rejuvenating but rebuilding organs and tissue and turning back the clock for ailing patients. Willerson is optimistic about the therapeutic future of stem cells, which can be extracted from fat cells, hair cells, and other diverse cell types. "I believe we will be able to regenerate the whole heart of a human being with stem cells," he says.

While the promise of stem cell therapy remains seductive, many questions remain about how to harness stem cells' power. Even in trials, which are designed to test effectiveness and safety, it's not always simple for researchers to determine whether a stem cell treatment is the cause of a patient's improvement. "With any [stem] cell-based therapy, there's such a high placebo effect," says Amit Patel, director of Cardiovascular Regenerative Medicine at the University of Utah and the national investigator on Benson's trial. "There's so much ... hype about the potential of stem cells. It's positive reinforcement." (In Benson's case, Patel says it's likely that the treatment is having a real impact, rather than a placebo effect, given that Benson lives at high altitude.) "Elevation—that's the ultimate stress test," he says.

In some ways, Benson is a particularly important subject for a clinical trial, because he's never been a smoker or drinker, and he doesn't have diabetes or coronary heart disease. (He developed heart failure after catching a virus several years ago.) Like Benson, about 40 percent of heart failure patients do not have coronary disease nor have they had a heart attack.