Using genetically altered mice, researchers may have figured out a way to turn on insulin production using just radio waves. The findings, published in Nature Medicine this week, could lead to a daily injection-free diabetes treatment without wires, implants, or even drugs.
Radio waves can freely penetrate tissue, and it’s already being used to control pacemakers. This new remote-controlled system—called “radiogenetics”—uses low-frequency radio waves to activate nanoparticles that are naturally in the body already. “The method allows one to wirelessly control the expression of genes in a living animal,” Jeffrey Friedman of Rockefeller University says in a news release. “Two key attributes are that the system is genetically encoded and can activate cells remotely and quickly.”
After experimenting with various configurations, Friedman and colleagues found that the optimal combination consists of using either low-frequency radio waves or a magnetic field to activate ferritin, a natural iron storage protein. By absorbing energy from radio waves at just the right frequency, these metal nanoparticles can open an ion channel called TRPV1, located in the membrane around cells. Then, calcium ions travel through the channel, switching on a synthetic piece of DNA that triggers the expression of an insulin-producing gene that’s further downstream.
“Ferritin, a protein-coated iron storage molecule, is normally found throughout the mouse and human body, but in our experiments, we modified it, placing the ferritin particles in different positions to see if we could improve our results,” Rockefeller's Sarah Stanley explains. “We found tethering the ferritin to the channel to be most effective.” To the right, the three components are pictured in a cell membrane: The iron nanoparticle (blue) is tethered by a protein (green) to an ion channel (red).
To test their system, the team introduced three genes into mouse liver cells, New Scientist explains: One encodes for ferritin, another codes for a protein that allows calcium to enter a cell when ferritin is exposed to the radio signal, and the third codes for insulin. That last gene is only active when calcium surges into the cell. The team showed that they could turn on insulin production in diabetic mice using just electromagnetic waves—successfully lowering their blood sugar.
Other remotely controlled systems exist, and they use light or drugs as a switch to control cell activity or gene expression. But until now, these systems required permanent implants or slow-working drugs. Here, the genes are introduced through gene therapy. “The use of a radiofrequency-driven magnetic field is a big advance in remote gene expression because it is non-invasive and easily adaptable,” Rensselaer Polytechnic Institute’s Jonathan Dordick says in a university statement. “You could have a wearable device that provides a magnetic field to certain parts of the body and it might be used therapeutically for many diseases.”
Images: S.A. Stanley et al., 2014 Nature Medicine