Can heart cells renew themselves, and can scientists help them do so? Two papers published online in Nature today suggest that heart muscle cells can make copies of themselves at a very low rate1, but that a genetic trick can prompt them to do a better job2. Those results give hope that hearts damaged by cardiovascular disease — which causes the deaths of almost 17 million people a year — could be coaxed to regenerate themselves. Heart muscle cannot renew itself very well. Researchers would like to help that process by finding populations of cells in the heart that can do so, and then boosting that capacity. But it has not been easy to find evidence of these regenerating cells, or to assess the extent of their powers.
The two Nature papers aim to get to the heart of the matter. In one, a team led by Richard Lee at the Brigham and Women’s Hospital and Harvard Medical School, both in Boston, Massachusetts, traced the birth and fate of heart muscle cells in mice. Lee and his colleagues found that a small proportion of heart cells — less than 1% — can regenerate themselves normally. After a heart attack that proportion goes up, but only to 3%. “These studies dispel any notion of the heart having a robust ability to regenerate,” says Charles (Chuck) Murry, who studies heart regeneration at the University of Washington in Seattle. That those cells exist at all is heartening, however. “If there is some capacity for the heart to produce new heart muscle cells, that’s a foothold that we can work with,” says Matthew Steinhauser, a co-author on the paper1 and a member of Lee’s lab. Then, he says, the team can ask: “Can we make it work better?”. A second group has done just that.