Neuromuscular junction formation by compartmentalized culture using human iPS cell-derived motor neurons and skeletal muscle cells.

The neuromuscular junction (NMJ) is a synapse that connects the nerve terminal of a motor neuron to a skeletal muscle fiber. The mechanisms underlying NMJ formation have been elucidated primarily through studies in animal models. However, elucidation of the pathophysiological mechanisms of human neuromuscular diseases and identification of potential therapeutic agents require the establishment of a human NMJ model. In this study, we established a human NMJ model using a compartmentalized culture system with cells derived from human induced pluripotent stem (iPS) cells, which enables quantitative and reproducible assessment of NMJ formation. During extended NMJ culture, morphological changes in the NMJ were observed, along with alterations in the expression of genes related to NMJ and skeletal muscle development, suggesting progressive NMJ maturation. The functionality of the formed NMJs was also confirmed using fluorescent live-cell imaging. These findings suggest that this human NMJ culture model may be applicable for investigating the pathological mechanisms of human neuromuscular diseases and exploring therapeutic agents.