Controlling a heartbeat with light

Over 17 million people die per year from heart related illnesses, and about threemillion more require pacemakers to stay alive. Researchers have now shown you can control the heartbeat of a fruit fly with light, using a technique known as optogenetics, which has large implications for researching heart problems.

The researchers, from Harvard and Lehigh University, were able to speed up and slow down a heartbeat using pulses of blue light. This is the first time this has been successfully done in fruit flies, although it has also been shown to work in zebrafish and mice. The advantage of using this technique in flies is that they have many genes in common with humans and are quite resistant to illness, so make good models for studying human heart disease.

The researchers, writing inScience Advances, genetically modified the flies to express a light-sensitive protein in their hearts. When the protein was exposed to light it stimulated the heart muscle, causing it to contract. As each flash of light corresponded to a contraction, the team could control the tempo and regularity of the heartbeat.

This might open up new possibilities to treat irregular heartbeats by using optical pacemakers. The standard pacemaker can sometimes stimulate muscles surrounding the heart, causing discomfort, and also requires a very invasive procedure.

"The neat thing about this optical pacemaker is that we don't have to implant anything to the heart, we just shine light and that light goes to the heart, stimulates the protein and effectively stimulates the heart contraction", lead researcher Chao Zhou explained.

However the team are quick to caution an optical pacemaker is at least twenty years away from becoming a reality. One challenge would be to get the light inside the human body, and another would be getting the light-sensitive protein to the heart without having to genetically modifying people, which Chao pointed out was not on the cards.

"We would never genetically engineer a human before they were born! One potential strategy is using a harmless virus to deliver these light-sensitive proteins to the heart."