All-optical system for control of wave dynamics in biological media.
Team first to use optogenetics to control excitation waves in heart cells.
We depend on electrical waves to regulate the rhythm of our heartbeat. When those signals go awry, the result is a potentially fatal arrhythmia.
For heart patients there are currently 2 options to keep these waves in check: electrical devices (pacemakers or defibrillators) or drugs (eg beta blockers). However, these methods are relatively crude: they can stop or start waves but cannot provide fine control over the wave speed and direction
Dr Gil Bub, from Oxford University explained: ‘When there is scar tissue in the heart or fibrosis, this can cause part of the wave to slow down. That can cause re-entrant waves which spiral back around the tissue, causing the heart to beat much too quickly, which can be fatal. If we can control these spirals, we could prevent that.
Optical control of spiral wave chirality in cardiac monolayer.
‘Optogenetics uses genetic modification to alter cells so that they can be activated by light. Until now, it has mainly been used to activate individual cells or to trigger excitation waves in tissue. We wanted to use it to very precisely control the activity of millions of cells.’
A protein called channelrhodopsin was delivered to heart cells using gene therapy techniques so that they could be controlled by light. Then, using a computer-controlled light projector, the team was able to control the speed of the cardiac waves, their direction and even the orientation of spirals in real time – something that never been shown for waves in a living system before.
This will allow experiments at a level of detail previously only available using computer models. They can now compare those models to experiments with real cells, potentially improving our understanding of how the heart works. The research can also be applied to the physics of such waves in other processes. In the long run, it might be possible to develop precise treatments for heart conditions. http://www.nature.com/nphoton/journal/vaop/ncurrent/full/nphoton.2015.196.html http://www.eurekalert.org/pub_releases/2015-10/uoo-rlh101515.php
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