Fix heart RHYTHM WITH LIGHT, NOT JOLTS
Electric shocks used to restore an irregular heart to a regular beat may soon be replaced by light—a kinder, gentler treatment, researchers say.
Jolts of current from a pacemaker or defibrillator can correct a life-threatening irregular heartbeat, but can hurt the patient, damage tissue, and cause other serious side effects, researchers say.
Biomedical engineers are using biological lab data and an intricate computer model to devise a low-energy light-based approach to bringing heartbeats back into synch. Other scientists already use light-sensitive cells to control certain activities in the brain. The team plans to apply this technique to the heart.
It was at Johns Hopkins that electrical engineer William B. Kouwenhoven developed the closed-chest electric cardiac defibrillator, used since the 1950s to save lives. But “applying electricity to the heart has its drawbacks,” says the new project’s supervisor, Natalia Trayanova, a biomedical engineer at the university.
“When we use a defibrillator, it’s like blasting open a door because we don’t have the key,” she says. “It applies too much force and too little finesse. We want to control this treatment in a more intelligent way. We think it’s possible to use light to reshape the behavior of the heart without blasting it.”
To achieve this, Trayanova’s team is diving into the field of optogenetics, which is only about a decade old. Pioneered by scientists at Stanford, optogenetics refers to the insertion of light-responsive proteins called opsins into cells. When exposed to light, these proteins become tiny portals within the target cells, allowing a stream of ions—an electric charge—to pass through. Researchers have begun using this tactic to control the bioelectric behavior of certain brain cells, forming a first step toward treating psychiatric disorders with light.
In a paper published online in Nature Communications, the researchers reported that they had successfully tested the technique on a virtual heart—one that “beats” inside a computer. Trayanova has spent many years developing highly detailed computer models of the heart that can simulate cardiac behavior from the molecular and cellular levels all the way up to that of the heart as a whole.
The new model incorporates biological data from the Stony Brook University lab of Emilia Entcheva, an associate professor of biomedical engineering. The Stony Brook collaborators are working on techniques to make heart tissue light-sensitive by inserting opsins into some cells. They also will test how these cells respond when illuminated.
“Experiments from this lab generated the data we used to build our computer model for this project,” Trayanova says. “As the Stony Brook lab generates new data, we will use it to refine our model.”
In Trayanova’s own lab, her team will use this model to conduct virtual experiments. They will try to determine how to position and control the light-sensitive cells to help the heart maintain a healthy rhythm and pumping activity.
Light beam therapy
They will also try to gauge how much light is needed to activate the healing process. The overall goal is to use the computer model to push the research closer to the day when doctors can begin treating their heart patients with gentle light beams. The researchers say it could happen within a decade.
“One of the great things about using light is that it can be directed at very specific areas. It also involves very little energy. In many cases, it’s less harmful and more efficient than electricity,” says Patrick M. Boyle, a postdoctoral fellow in Trayanova’s lab and lead author of the study.
After the technology is honed through the computer modeling tests, it could be incorporated into light-based pacemakers and defibrillators.
The National Institutes of Health and National Science Foundation funded the research, supplemented by an individual fellowship from the Natural Sciences and Engineering Research Council of Canada.
Source: Johns Hopkins University