Health reporter, BBC News online
Scientist say they have managed to turn patients' own skin cells into healthy heart muscle in the lab.
Ultimately they hope this stem cell therapy could be used to treat heart failure patients.
As the transplanted cells are from the individual patient this could avoid the problem of tissue rejection, they told the European Heart Journal.
Early tests in animals proved promising but the experimental treatment is still years from being used in people.
Experts have increasingly been using stem cells to treat a variety of heart problems and other conditions like diabetes, Parkinsons disease or Alzheimer's.
Stem cells are important because they have the ability to become different cell types, and scientists are working on developing ways to get them to repair or regenerate damaged organs or tissues.