Researchers at UW Medicine in Seattle have successfully used human stem cells to restore heart function in monkeys with heart failure. The findings suggest that the technique will be effective in patients with heart failure, the leading cause of death in the world.
Most heart failure is caused by the death of heart muscle due to heart attacks. Because heart muscle does not regenerate, the damaged areas are replaced with scar tissue, which does not contract. As a result, the heart grows weaker. At a certain point, the heart can no longer pump enough blood to supply the body with the oxygen it needs to function. This is called heart failure. Symptoms include fatigue, profound weakness and shortness of breath. About 6.5 million Americans live with heart failure, and more than 600,000 die of the disease each year. Currently, there is no way to restore the heart’s lost muscle function.In the new study, the researchers induced experimental heart attacks in macaque monkeys. Macaques were chosen because their heart size and physiology are close to that of humans. The heart attacks reduced the hearts’ left ventricular ejection fractions — a measure of how much blood the heart pumps per beat — from about 65 percent to 40 percent, enough to put the animals into heart failure.
Two weeks later, the researchers took heart cells that they had grown from embryonic human embryonic stem cells and injected them into and around the young scar tissue. Each animal received roughly 750 million of these human embryonic stem cell-derived cardio-myocytes. For comparison, a control group was injected with a cell-free version of the solution that was used to inject the stem cells into the treatment animals.
The researchers found that, at four weeks after treatment, the ejection fraction of the untreated control animals remained essentially unchanged, It stayed at about 40 percent, but in the treated animals the ejection fraction had risen to 49.7 percent, about half-way back to normal. Magnetic resonance imaging, or MRI, scans showed that new heart muscle had grown within what had been scar tissue in the treated hearts, while no new muscle was seen in the untreated animals. — Courtesy: Sciencedaily.com