There's no denying that pacemakers are life-saving devices, but they do have their limitations. These include the facts that their metal leads can break, they need to be surgically accessed if their batteries run out, and they can be disrupted by strong magnetic fields. Some or all of these problems may one day become things of the past, however, due to research currently being conducted at New York's Stony Brook University - scientists there are working towards the development of pacemakers that control the heart through pulses of light.
Using an approach known as non-viral optogenetics, the research team has successfully taken cells from donors, modified them to respond to light, then coupled them to existing heart cells. The result was heart tissue that contracted when exposed to light, in a fashion that was indistinguishable from contractions caused by electrical stimulation. While light has been used to activate tissue before, this was apparently "the lowest light energy ever reported to control electrical activity in excitable tissue."
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The modification process involved genetically altering the cells to produce channelrhodopsin 2, a light-sensitive protein. If these cells were obtained from a patient's own body, such as from their bone marrow or skin, the chances of their being rejected when implanted in the heart would be greatly diminished. The process would also not involve the cells having to be brought into the patient's body inside viruses, or the introduction of genes from other organisms.
Of course, the cells themselves wouldn't be able to do much without a source of light, which is where the light-emitting pacemakers would come in. Although it has yet to be developed, the Stony Brook scientists believe that such a device would consume less power than present-day electrical pacemakers, which would translate into longer battery life.
Dr. Emilia Entcheva, who is leading the project, thinks that the technology could also be used in muscle actuators and defibrillators, and for lab-testing new drugs for possible cardiac side effects.
The research was recently published in the journal Circulation: Arrhythmia & Electrophysiology.