Nagoya journal of medical science

Successful transplantation of motoneurons into the peripheral nerve depends on the number of transplanted cells.

PMID 25797991


Transplantation of motoneurons (MN) into the peripheral nerve to provide a source of neurons for muscle reinnervation, termed motoneuron integrated striated muscle (MISM), may provide the potential to restore functional muscle activity, when combined with computer-programmed functional electrical stimulation (FES). The number of MNs required to restore innervation to denervated muscles in adult Fischer 344 rats was investigated by comparing two groups, one transplanted with 2 × 10(5) cells (group A) and the other with 1 × 10(6) cells (group B). Twelve weeks after transplantation, electrophysiological analysis, muscle function analysis, and tissue analysis were performed. The mean motor nerve conduction velocity was faster (12.4 ± 1.0 m/s vs. 8.5 ± 0.7 m/s, P = 0.011) and the mean amplitude of compound muscle action potential was larger (1.6 ± 0.4 mV vs. 0.7 ± 0.2 mV, P = 0.034) in group B. The dorsiflexed ankle angle was larger in group B (27 ± 5° vs. 75 ± 8°, P = 0.02). The mean myelinated axon number in the peroneal nerve and the proportion of reinnervated motor end plates were also greater in group B (317 ± 33 vs. 104 ± 17, 87.5 ± 3.4% vs. 40.6 ± 7.7%; P < 0.01, respectively). When sufficient MNs are transplanted into the peripheral nerve, MISM forms functional motor units. MISM, in conjunction with FES, provides a new treatment strategy for paralyzed muscles.