For the first time, researchers show that the heartbeats of live fruit flies can be controlled using light. The work, published in Science Advances this week, suggests that abnormal heart rhythms could be evened out without the electrical stimulation provided by pacemakers.
For more than a century, low-energy shocks have been used to pace neurons and heart cells. But a light-activated way to make the heart beat regularly – called optical or optogenetic pacing – could provide for a non-invasive alternative. The technique would be specific to target cells (in this case, cardiac tissue) and shouldn’t generate toxic gases, alter pH levels, or cause tissue damage.
So, Lehigh University’s Aneesh Alex and colleagues genetically engineered Drosophila melanogaster fruit flies to express a light-sensitive protein in their heart cells. They also developed a real-time imaging technique to monitor how the flies’ hearts respond to light. These fruit flies share many similarities with vertebrates during the early stages of heart development as well as in the underlying genetic mechanisms that regulate cardiac function. About 75% of disease-causing genes in humans have functional counterparts in Drosophila.
When the hearts of these flies were hit through the exoskeleton with blue laser light pulses, each pulse triggered a heart contraction. Using their light-based technique, the researchers were able to use to slow down and speed up heart rhythm in flies at various stages of their lifecycle: from larva to pupa to adult.
Heart rhythm of fruit flies at different developmental stages can be noninvasively controlled by light using optogenetics. Alex, et al, Lehigh University
Optogenetic tools similar to the one described here have been widely used in neuroscience to control the function of neurons. But until now, light-activated heart pacing has been limited to zebrafish hearts at an early developmental stage and mice who had to have their chest walls surgically opened. Developing the technique for fruit flies can enable new kinds of research in cardiology, study author Chao Zhou of Lehigh University told IEEE Spectrum. A fruit fly-based platform could be useful for studying the mechanisms that underlie heart arrhythmia in humans and makes it possible for the development of optical cardiac pacemakers.
Additionally, when the team conducted safety testing, they found no observable long-term adverse effects on Drosophila heart development.