Researchers have transfected guinea pig hearts with a copy of the human TBX18 gene to create a new biological pacemaker that controls heartbeat. The TBX18 gene is active in human embryonic hearts at the stage where pacemaker cells are formed. The study has led to hopes that the technique may work for human hearts in the future. For more on this story see www.bbc.co.uk/news/health-20713986.