Functional reconstruction with motoneuron integrated striated muscles (MISM)
Epublication WebSurg.com, Jan 2014;14(01). URL: http://websurg.com/doi/lt03enhirata001
This study is made up of two parts. The first part is an animal experiment to develop a novel surgical technology named motoneuron-integrated striated muscles (MISM) technology. The second part is the introduction of a new human machine interface technology based on tacit learning. By combining the two advanced technologies, we have been trying to develop a future treatment for currently untreatable nerve palsies. Re-innervation of denervated muscle by motoneurons transplanted into the peripheral nerve may provide the potential to excite muscles artificially with functional electrical stimulation (FES). We transplanted embryonic motoneurons into the peripheral nerve of adult Fischer 344 rats after transection of the sciatic nerve. One week after sciatic nerve transection, medium with or without dissociated embryonic spinal neurons was injected into the distal stump. Electrophysiological and tissue analyses were performed 12 weeks after transplant, as well as a naive control group which received no surgery. In the cell transplant group, the ankle angle was measured during gait with and without FES of the peroneal nerve. Transplanted motoneurons survived in the peripheral nerve and formed functional motor units. In the cell transplantation group, ankle angle at mid-swing was more flexed during gait with FES (26.6 ± 8.7°) than gait without FES (51.4 ± 12.8°, p=0.011), indicating that transplanted motoneurons in conjunction with FES restored ankle flexion in gait, even though no neural connection between central nervous system and muscle was present. These results indicate that transplant of embryonic motoneurons into peripheral nerve combined with FES can provide a new treatment strategy for paralyzed muscles. For the successful clinical application of MISM technology, the development of a human machine interface is key. We have developed a novel computer program, the tacit learning program, which can analyze patient intention and automatically adjust limb motion with minimum mental/physical burden on the human side. I am going to introduce a newly developed multi-degree of freedom electric-powered arm based on tacit learning to demonstrate the efficacy of the technology.