Biological Pacing

The adult human heart beats almost 100,000 times a day, in a rhythm dictated by a small number of pacemaker cells. “The mammalian heart beats spontaneously without conscious input from the brain,” says Hee Cheol Cho (above), associate professor in the Department of Pediatrics and the Coulter Department of Biomedical Engineering at Emory and Georgia Tech. Aging and heart defects can cause the pacemaker cells to malfunction, leading to abnormal or slow heart rhythms. In these cases, doctors implant mechanical pacemakers, which are expensive and have potential complications. Cho and his team have been working to develop a device-free way to pace the heart. They discovered that an embryonic gene, TBX18, figures prominently during the formation of pacemaker cells in the embryo and can convert ordinary heart muscle cells into new pacemaker cells. Cho is testing long-term biological pacemakers in animal models. “Our technologies have matured sufficiently to draw up a roadmap toward the first-in-human clinical trial in the next few years,” he says.—Aspen Ono