The First Optical Pacemaker

According to a short news release from the Optical Society of America (OSA), an international team of scientists at Osaka University in Japan has used a femtosecond laser pacemaker to control heart muscle cells. So far, this optical pacemaker will only be used for laboratory research. As writes OSA, ‘exposing heart muscle cells to powerful laser pulses can have its drawbacks. Although the laser pulses last for less than a trillionth of a second, damaging effects can build up over time and this currently limits the possibility of clinical applications.’ Still, it’s a very interesting new technique to study the heart. But read more Here is how this optical pacemaker works. The laser was focused inside the cell using 30 mW of average power, and 8 ms exposures occurred at 1 Hz intervals. The time sequence is (a) 1 sec, (b) 8 sec, (c) 14.7 sec, and (d) 16.7 sec.”

[Note: Here is a definition of what are “cardiomyocytes” provided by Osaka University. They “are the muscle cells that provide for the contractility of bulk heart tissue. They exhibit a fascinating and complex range of dynamic behavior that forms the building blocks of the physiology of the heart, and have been the subject of a vast number of interspecies studies in biomedical fields.”]

This research project has been led by Nicholas Smith, an assistant professor working in the Laboratory for Scientific Instrumentation and Engineering (LaSIE) of the Department of Applied Physics at Osaka University. He was supervised by Satoshi Kawata, director of LaSIE and professor at both the Department of Applied Physics and the School of Frontier Biosciences.

Here is an excerpt from the OSA news release describing how this laser technology could be used in labs. “One potential application of this technology is in studying uncoordinated contractions in heart muscle. Normally, heart muscle contracts in a highly coordinated fashion, and this is what allows the heart to pump blood through the vasculature. But in some people, this coordinated beating breaks down, and the heart twitches irregularly — a condition known as fibrillation. The new laser technique may allow scientists to create a form of fibrillation in the test tube. The lasers can destabilize the beating of the cells in laboratory experiments by introducing a beat frequency in one target cell distinct from the surrounding cells. This would allow scientists to study irregular heart beats on a cellular level and screen anti-fibrillation drugs.”

For more information, this research work has been published online in Optics Express under the name “A femtosecond laser pacemaker for heart muscle cells” (Volume 16, Issue 12, Pages 8604-8616, June 2008).

The researchers also write that this technique could be used to synchronize contractions in heart muscle cells. “Although there are other simpler methods by which to synchronize cardiomyocytes (e.g. electrical current-based regulation of contraction or even photolysis of loaded caged compounds), the femtosecond laser interaction may be a useful tool with which to apply a driving stimulus that can synchronize contractions in heart muscle cells and may possibly be able to penetrate through substantial depths of heart muscle tissue due to the multiphoton absorption and may facilitate the investigation of such synchronization in-vivo, where other methods cannot be used or cannot achieve the same degree of subcellular localization.”

Source: Optical Society of America