Patching a damaged heart with a patient’s own muscle stem cells improves symptoms of heart failure, according to a small Japanese study.

Researchers made patches out of cells from the thigh muscles of 27 heart failure patients who had limited exercise capacity and weren’t responding well to common heart failure treatments.

One year after the patches were surgically glued onto the surface of their hearts, patients had improved exercise capacity and heart function.

Therapies to treat heart failure — including drugs, implantable devices and heart transplantation — aren’t good long-term options. So regenerating a damaged heart with a patient’s stem cells may be a viable alternative, researchers said.

Larger clinical trials are needed to validate the findings of the study, which is published in the Journal of the American Heart Association.