Establishment of a novel nerve organoid for sequential analyses of morphological and functional changes underlyingperipheral neuropathy pathogenesis

Abstract

Few in vitro experimental systems have been optimized for the analysis of the peripheral nervous system (PNS) aimed at elucidating the complex mechanisms underlying the development of peripheral neuropathy. To address this issue, we developed a novel sensory nerve organoid derived from rat embryonic dorsal root ganglion. An innovative advance of present study is that the organoid was composed of independent ganglionic and axonal bundle morphology, which contained unmyelinated C-fibers and A-fibers stereo-myelinated by Schwann cells. After nerve ablation, the axons had almost completely regenerated 2 weeks after injury, indicating that organoids have characteristics specific to the PNS. We also confirmed the mRNA expression of functional molecules (ion channels and receptors), which play important roles in pain transmission, in neuronal cell bodies of organoids. Furthermore, present Ca²⁺ imaging analysis showed that focal application of KCl (30 mM) onto the nerve endings induced Ca²⁺ influx into the neuronal cell bodies. One day after axonal transection, the mRNA expression of stress inducible genes increased in the ganglion. Taken together, this organoid enables real-time evaluation of subtle changes in the PNS, and is considered to be a useful tool for further developing peripheral neuropathy research.