Optimization of embryonic ESC-derived motor neuron grafts for restoration of lost muscle function (360G-Wellcome-109002_Z_15_A)

Damage to motor neurons due to traumatic injury or degenerative conditions typically results in permanent muscle denervation and paralysis. We recently described1 a novel strategy to artificially restore functional control of paralyzed muscles, which employs embryonic stem cell-derived motor neurons (ESC-MNs), modified to express channelrhodopsin-2 and glial derived neurotrophic factor, to confer optogenetic control of neural activity and promote long-term survival, respectively. These ESC-MNs, contained within embryoid bodies (EBs), were engrafted into injured peripheral nerves of mice, resulting in reinnervation of paralyzed muscles and optical control of their function. Unfortunately, EBs contain pluripotent cells with an inherent potential to form teratomas, limiting their clinical utility. However, purified ESC-MN grafts have a limited to capacity to functionally reinnervate muscle targets because other cell types within EBs, particularly excitatory interneurons, appear necessary for successful reinnervation of target muscles by engrafted ESC-MNs. The aims of this project are to i) optimize the ESC-MN graft identity, by investigating the effect of interneurons on motor neuron maturation and muscle innervation; ii) to use the optimized grafts to reinnervate opposable flexor and extensor muscles, to demonstrate the therapeutic utility of this approach in the restoration of complex functions, such as hand grasping.