Patients with mild or moderate heart failure who have high levels of inflammation responded well to stem cell injections, and experienced a decline in their risk of heart attacks, strokes, and heart-related death, according to clinical trial results.

Stem cells injected into targeted areas of a failing heart become activated by inflammation and start pumping out beneficial biochemicals, explained lead researcher Dr. Emerson Perin, medical director of the Texas Heart Institute in Houston.

“These cells are little factories of different proteins, cytokines and other products that then have an effect locally on the heart muscle cells,” Perin said, adding that the cells also help improve the health of blood vessels both large and small.

Researchers recruited 537 people suffering from advanced heart failure with reduced ejection fraction, which is when the main pumping chamber in the left side of the heart is significantly weakened. Half of the patients chosen at random received 150 million stem cells into targeted areas of still-working heart muscle, delivered through 15 to 20 injections in a single procedure.

All the patients who got stem cells experienced a 65 percent reduction in nonfatal heart attacks and strokes. Participants with high levels of inflammation were 79 percent less likely to have nonfatal heart attacks or strokes after stem cell therapy.