Fat Cells for Broken Hearts

A company is testing whether stem cells from fat could help prevent long-term damage after a heart attack.

Too much fat around the waist may be bad for your health, but the stem cells it contains might one day save your life. Starting this month, a new European trial aims to determine whether stem cells harvested from a person's own fat, delivered shortly after a heart attack, could prevent some of the cardiac muscle damage that results from blocked arteries.

During a heart attack, blood vessels that deliver blood to the heart muscle are blocked, and the lack of oxygen slowly kills the tissue. San Diego-based Cytoryi Therapeutics has developed a treatment that aims to prevent much of that muscle damage before it starts. It works by injecting a concentrated slurry of stem cells and other regenerative cells isolated from the patient's body directly into the heart's main artery within 24 hours after an attack. "Time is muscle. The quicker you get in, the better," says Christopher Calhoun, Cytori's chief executive officer. "You can't do anything about dead tissue, but tissue that's bruised and damaged—that's revitalizable. If you can get new blood flow in there, that tissue comes back to life."

Adult stem cells, which exist in small populations throughout the body, can differentiate to form specific tissue types and are responsible for repairing injuries and replacing dying cells. The prospect of using them to heal damaged heart muscle has tantalized biomedical researchers for more than two decades. If the stem cells come from a patient's own body, there is no risk of rejection. A number of clinical trials in recent years have focused on using stem cells collected from bone marrow, since this potent population can differentiate into both cardiac muscle cells and blood vessel cells, among other types. But marrow stem cells are difficult to collect and somewhat scarce; they must be isolated and then grown in culture before they're injected back into an injured heart. The process can take weeks.

Cytori has created a portable machine that, in less than an hour, can reduce a sample of fat "about the size of a can of Coke," Calhoun says, to less than a teaspoon of concentrated slurry that Cytori believes contains its most vital elements: stem cells, smooth muscle cells, cells that line blood vessels, and a number of other regenerative cells that can promote growth healing.

Cytori began a large-scale trial this month and hopes to test the procedure on 360 patients. The company aims to start large-scale clinical trials on heart attack patients in the United States by 2014 and on patients with chronic heart failure even earlier than that.

But it's still early. Clinical trials of stem cells derived from bone marrow have shown mixed results in treating heart disease, and it's unclear whether fat-derived cells will fare better. "If it works, it would be wonderful to have a ready-made source of autologous stem cells," says Richard Schatz, research director of cardiovascular interventions at Scripps Health in San Diego, one of the inventors of the coronary stent. But he and others note that it will take many more trials to determine how effective Cytori's methods are compared with treatments based on marrow stem cells.