echnion researchers in Israel have successfully established a new approach for pacing the heart and synchronizing its mechanical activity without the use of a conventional electrical pacemaker. This novel biologic strategy employs light-sensitive algal genes that can be injected into the heart and then activated by flashes of blue light.
Pacing the heart with light is part of the emerging field of optogenetics, which has gained considerable momentum in the field of brain research. Researchers working in the field have been taking light-sensitive genes from algae and placing them in cells where they act like a switch, turning certain behaviors on or off when the cells are exposed to pulses of light.
The new optogenetic approach for cardiac pacing and resynchronization was developed by Prof. Lior Gepstein and Dr. Udi Nussinovitch of the Technion-Israel Institute of Technology’s Rappaport Faculty of Medicine, and Rambam Medical Center.
As they report in the journal Nature Biotechnology, the Technion researchers injected one of these algae genes (channelorhodopsin-2) into a specific area of a rat heart muscle. The scientists then showed that the light-sensitive protein expressed at this site could be turned on with flashes of blue light and drive the heart muscle to contract. By altering the frequency of the flashes, Gepstein and Nussinovitch could control and regulate the heart rate.
They went on to deliver the gene to several places in the heart’s pumping chambers, and demonstrated the ability to simultaneously activate the heart muscle from many places in an effort to synchronize the heart’s pumping function.
“Our work is the first to suggest a non-electrical approach to cardiac resynchronization therapy,” Gepstein said. “Before this, there have been a number of elegant gene therapy and cell therapy approaches for generating biological pacemakers that can pace the heart from a single spot. However it was impossible to use such approaches to activate the heart simultaneously from a number of sites for resynchronization therapy.”
If the biological pacemaker can be adapted for humans, it could help patients avoid many of the drawbacks of electrical pacemakers. These include the surgical procedure needed to implant the device, the risk of infection, the limitation on the number and locations of the pacing wires used, the possible decline in cardiac function resulting from the change in the normal electrical activation pattern, and the limitations on implantation in children.