Optical Control of Muscle Function by Transplantation of Stem Cell–Derived Motor Neurons in Mice

Optogenetics Applied to Motorneuron Control Nerves damaged by disease or injury do not always regenerate. In such cases, therapies involving transplanted stem cells show some promise. However, the new neurons derived from transplanted cells cannot communicate with the central control systems that would normally regulate movement. To avoid the need for such communication, in a proof-of-principle study, Bryson et al. (p. 94 ; see the Perspective by Iyer and Delp ) added optogenetic control to differentiation and transplantation of motor neurons. In the mouse, these engineered neurons were able to reestablish connections within a damaged sciatic nerve and, when activated by localized light stimulation, could drive muscle contractions.