Optogenetic control of live skeletal muscles: Non-invasive, wireless, and precise activation of muscle tissues

Optogenetics is an emerging new technology for controlling live cell function with light. Skeletal muscles are genetically coded to express light-sensitive proteins so that the cell's behavior may be altered by illuminating a targeted portion of the cell. Optogenetic control provides a non-invasive, wireless, and fast control method with high spatiotemporal resolution. This paper presents the technology, experimental test, and potential applications of optogenetic control of skeletal muscles. The authors' research team has recently succeeded in controlling the contraction of skeletal muscle tissues with light by using the light-sensitive protein Channelrhodopsin 2 (ChR2). Precursors of skeletal cells, myoblasts, are transfected with ChR2, creating ion channels on the cell membrane that conduct cations when exposed to blue light. Experiments show that targeted skeletal muscles are activated rapidly and precisely with high spatiotemporal resolution. Dynamics of optogenetically controlled skeletal muscles are characterized based on system identification. Two potential applications are addressed. One is muscle-on-a-chip drug screening for evaluating potential hazards of a drug on muscular function, and the other is multi-DOF robotic devices powered by bio-artificial muscles controlled with targeted light illumination.