Their work could lead to the development of a new kind of implantable defibrillator for heart patients.
Currently these kinds of devices carry pulses of electricity (that are painful and cause heart tissue damage), however, light-based treatment may be able to provide a safer and gentler solution for patients at high risk of arrhythmia, an irregular heartbeat that can cause sudden cardiac death in just minutes.
This idea is a result of recent advances in the field of optogenetics, which works with light-sensitive proteins that are embedded in living tissue, allowing the use of light sources to modify electrical activity in cells.
“We are working towards optical defibrillation of the heart, where light will be given to a patient who is experiencing cardiac arrest, and we will be able to restore the normal functioning of the heart in a gentle and painless manner,” said Natalia Trayanova, the Murray B. Sachs Professor in the Department of Biomedical Engineering, who supervised the research at Johns Hopkins.
To develop the new heart treatment, the scientists conducted tests on beating mouse hearts whose cells had been genetically engineered to express proteins that react to light and alter electrical activity within the organ.
When the researchers prompted ventricular fibrillation in the mouse heart, a light pulse of one second applied to the heart was enough to restore normal rhythm.
“This is a very important result,” said Tobias Bruegmann, one of the lead authors of the journal article. “It shows for the first time experimentally that light can be used for defibrillation of cardiac arrhythmia.”
In order to determine whether this technique would also be beneficial in human patients, the Johns Hopkins team performed an experiment on a detailed computer model of a human heart—created from MRI scans taken of a patient who had experienced a heart attack and is now at risk of arrhythmia.
“Our simulations show that a light pulse to the heart could stop the cardiac arrhythmia in this patient,” said Patrick M. Boyle, a Johns Hopkins biomedical engineering research professor who was also a lead author of the journal article.
The experiment was altered slightly to adjust to the human heart and its needs, but overall the simulations revealed the precise ways that light modifies the collective electrical behavior of heart cells and can stop arrhythmia.
The team makes sure to note the importance of advancements in technology, which allowed them to create computational models, and can accelerate the development of therapeutic applications for cardiac optogenetics.
“The new method is still in the stage of basic research,” said Junior Professor Philipp Sasse of the Institute of Physiology at the University of Bonn. “Until implantable optical defibrillators can be developed for the treatment of patients, it will still take at least five to ten years.”
A video regarding the research can be seen here.