How do you mend a broken heart? Stem cells. Or at least that's the hope after scientists successfully used lab-created heart muscle cells to partially repair damaged hearts in monkeys, Live Science reports. The healthy stem cells were easily absorbed into the damaged hearts and allowed the organ to pump blood more easily. The procedure could lead to a new way to treat heart attacks and at least partially repair heart damage, the Guardian reports. Heart disease is the leading cause of death for men and women in the US. Scientists are intrigued by the idea of treating damaged hearts by using a patient's own skin cells to create healthy heart cells, which are less likely to be rejected since they don't come from a donor. In the latest study in the journal Nature, the team at Shinshu University induced heart attacks in five macaques and then injected them with heart cells made from the skin of a healthy macaque who was a close genetic match.
To avoid rejection, they ensured the donor monkey had a type of protein similar to the recipients' and they gave the sick monkeys anti-rejection drugs. After studying the macaques for three months, researchers found their immune systems tolerated the new cells, which replaced about 16% of the damaged heart tissue. In the end, the monkeys' heart muscles contracted better, pumping blood more efficiently. Human trials are not coming anytime soon, though, after the macaques developed irregular heartbeats. Still, doctors said the findings raise the possibility of treating damage caused by heart attacks. "Currently, the only long term option for these patients is heart transplantation, but there are not enough donors to meet the current demand," heart researcher Sam Boateng told the Guardian. (Monkeys on a strict low-calorie diet lived much longer.)