Scientists have created many different implantable devices and medicines that are as simple as pacemakers or as complex as nanobiosensors. Now researchers are learning how to use electricity to control gene expression. For example, a diabetic might one day use an app on their smartphone after they've eaten; their blood sugar will rise, so the app would send a signal to their implant to raise insulin levels.
Martin Fussenegger, Professor of Biotechnology and Bioengineering in the Department of Biosystems Science and Engineering at ETH Zurich in Basel is working with a team of researchers to make this kind of electrically-controlled gene expression a reality. As the first step, they used a mouse model to demonstrate that gene expression can be controlled with an electrical signal. The work has been reported in Science.
The research team has already created gene circuits and implants that can react to various conditions in the body, like abnormal blood sugar or lipid levels. These networks can respond to drugs and natural molecules, but they can also react to other kinds of stimuli like light, and now, electricity.
"We've wanted to directly control gene expression using electricity for a long time; now we've finally succeeded," Fussenegger said.
The device is made of a printed circuit board (PCB) with the electronic components - a receiver and a control unit. The other side holds a capsule containing human cells (with genomes in their nuclei), with a cable linking the PCB to the capsule. Radio signals can activate the implant's electronics, and they transmit the signal to the cells.
The electricity alters channels in the membranes of the cells, changing the concentration of ions in the cells and triggering a signaling pathway that regulates insulin gene expression. Insulin is then loaded into vesicles, and the electrical signals cause them to merge with the cell membrane and release the insulin. This all happens within a few minutes.
"Our implant could be connected to the cyber universe," noted Fussenegger. Though that might sound a little worrisome to some, the researchers are aware that there is a risk that these devices could be exploited in some way.
"People already wear pacemakers that are theoretically vulnerable to cyberattacks, but these devices have sufficient protection. That's something we would have to incorporate in our implants, too," he said.
It would also be possible for insulin production to be triggered remotely by a doctor. "A device of this kind would enable people to be fully integrated into the digital world and become part of the Internet of Things - or even the Internet of the Body," Fussenegger said.
There are still hurdles before this is something people use. The scientists have to learn about the best electrical current for the device, and the links between the electronics and cells have to be optimized. There should be a better way to replace the cells in the implant once they are worn out as well. Finally, these devices have to be thoroughly tested for safety.