A new method of stimulating heart muscle cells could lead to the creation of pacemakers that are remotely controlled with low-energy light. Employing optogenetics, researchers at Stony Brook University introduced light-sensitive proteins into cells, demonstrating a way to control cell excitation and contraction in cardiac muscle cells. They said that this technique may help form the basis for a new generation of light-driven cardiac pacemakers and other medical devices. Emilia Entcheva, senior author, noted that although electronic cardiac pacemakers and defibrillators have long been established and successful, they still have issues such as the breakage of metal leads, limited battery life and interference from strong magnetic fields. “Eventually, optical stimulation may overcome some of these problems and offer a new way of controlling heart function,” she said. A few years ago, investigators discovered that brain cells could be stimulated using light if they were genetically altered to produce a light-sensitive protein called channelrhodopsin 2 (ChR2). As part of the new study, researchers created cells expressing the ChR2 protein and coupled them with heart muscle cells from animals, creating heart tissue stimulated by light. They found that light-triggered heart muscle contractions and electrical waves were indistinguishable from electrically triggered waves. Instead of directly modifying heart cells, the researchers coupled donor cells optimized for light responsiveness with the heart cells. The new technique uses less energy and doesn't require the use of viruses or the introduction of genes from other organisms. Instead, cells from a person's bone marrow or skin can be cultured and modified to respond to light. Using the patient’s own cell reduces the possibility that the immune system will reject the light-sensitive cells. The approach may someday be used in pacemakers and defibrillators that would feature biocompatible, flexible plastic optic fibers. The preliminary research suggests that the light-based system might require only one-tenth the energy, meaning that a battery could last 50 years rather than five. The study was published in Circulation: Arrhythmia & Electrophysiology, a journal of the American Heart Association. For more information, visit: www.stonybrook.edu