Despite its importance, the heart is one of the few tissues in the human body that can't repair damage very well – or at least, that's what has long been presumed. Scientists in Australia have now caught heart muscle cells freely regenerating after a heart attack. When something impedes blood flow, the lack of oxygen kills heart cells. The organ can patch itself up with scar tissue , but this inelastic, fibrous tissue doesn't beat, making the heart less efficient. These irregularities can