http://www.nature.com/news/light-opens-up-the-larynx-1.17662Scientists have genetically engineered muscles to move in response to pulses of light. The technique, demonstrated on vocal cords removed from mice, is reported on 2 June in Nature Communications1. Researchers say that it could probe how muscles function — and might eventually help to treat people who have a paralysis that interferes with speech and breathing. The work relies on a method called optogenetics, which can make cells that usually respond to electrical signals also react to light. The approach alters mammalian cells by inserting a gene for a protein such as channelrhodopsin, which in its natural setting allows blue-green algae to swim towards or away from light. Optogenetics was first used in 2005 to modify neurons, and has since become a standard tool to study the brain and nervous system. Applications outside neuroscience, however, are less common.
The latest study is fascinating, says Julio Vergara, a physiologist at the University of California, Los Angeles, who studies how electrical signals cause muscles to contract. “It shows the potential use of this very powerful technique for very important medical problems,” he says. The study's authors had previously used optogenetics to engineer heart muscle in mice3 — light caused parts of the heart to beat out of sync, simulating arrhythmias. The latest research extends this to muscles that move under conscious command. “Skeletal muscles follow different rules than the heart,” says Philipp Sasse, a co-author of the study and a physiologist at the University of Bonn in Germany. “Each fibre in a skeletal muscle can contract separately, which allows controlling movements as well as muscle strength very precisely.”
