Have a Heart

For years, researchers have known that adult zebrafish, and other fish and amphibians, can regenerate their damaged hearts. The phenomenon, however, has never been seen in mammals — until now. Researchers at the University of Texas Southwestern Medical Center report in Science this week their discovery that newborn mammalian hearts can heal themselves, says The New York Times' Sindya Bhanoo. The researchers found that if they removed about 15 percent of a newborn mouse's heart within the first week of its life, the heart grew back, Bhanoo says. After that first week, the ability to regenerate tissue is lost and heart failure occurs if the heart is damaged, the researchers add in their study. The team is unsure whether cardiomyocytes or stem cells are contributing to the regeneration, but they are searching for the genes that regulate the process in the hopes of finding ways to treat heart disease, Bhanoo says.