By Clara MoskowitzStaff writer updated 4/2/2009 2:52:39 PM ET It was long thought that the human heart, like the brain, was unable to grow new cells after birth. But today scientists announced the first evidence that new heart cells are made throughout a person's life. Brain cells also grow and change well into adulthood, scientists announced a few years ago. "If you cut your skin, your skin can heal. If you break your bone, bones can heal. But organs like the heart and brain, people thought, couldn't make new cells ," said Ratan Bhardwaj of the University of Toronto. "But now we've shown that the human heart does make new cells." Bhardwaj and colleagues detail their discovery in the April 3 issue of the journal Science. "We feel that this is a very fundamental breakthrough in basic science," Bhardwaj told LiveScience. "We totally open the door for future therapies." For instance, the finding could help doctors design treatments ...