Controlling insulin production with a smartwatch
LEDs are built into many current fitness trackers and smartwatches. The continuous or pulsed green light that is emitted penetrates the skin and can be used to monitor the wearer's heart rate during physical activity or at rest. The popularity of these watches has skyrocketed which led the group of ETH researchers to take advantage of this popularity by utilizing LEDs to control genes and affect cell behavior through the skin. Martin Fussenegger of Basel's Department of Biosystems Science and Engineering leads the team. "No naturally occurring molecular mechanism in human cells responds to green light, so they had to construct something new," he says, explaining the difficulties of the task.
The ETH researcher and his team eventually devised a molecular switch that can be activated by a smartwatch's green light once implanted. The switch is linked to a gene network that scientists introduced in human cells. For the prototype, they used HEK 293 cells, as is normal. As soon as the cells are exposed to green light, depending on the architecture of this network – that is, the genes it contains – it can generate insulin or other compounds. Turning off the light deactivates the switch and brings the process to a halt.
The researchers used the standard smartwatch software to switch on a gene network in cells. They activated the green light by launching the running app throughout their experiments. According to Fussenegger, "off-the-shelf watches offer a universal solution to flip the molecular switch." New models emit light pulses that are considerably more effective in maintaining the gene network's functionality. A molecular complex was integrated into the cell membrane and connected to a connecting piece, like a railway carriage coupling. When green light is emitted, the component that projects into the cell detaches and travels to the nucleus, where it activates an insulin-producing gene. The detachable portion reconnects with its counterpart implanted in the membrane once the green light has been turned off.