The Study Of Directional Growth And Development Of Spiral Ganglion Neurons Regulated By Superparamagnetic Iron Oxide Nanoparticles And Magnetic Field

Spiral ganglion neurons(SGN)are the first neuron in auditory signal transduction pathway,which plays an important role in auditory transmission.Ototoxic drugs,aging,noise pollution,heredity and other factors can easily trigger the secondary degeneration between spiral ganglion neurons and cochlear hair cells or the connection barrier between spiral ganglion neurons and hair cells,which could initiate sensory nerve deafness.Importantly,injured spiral neurons have limited self-repairing ability.SGN protection and regeneration are potential ways to treat hearing impairment.How to promote the development of SGN morphology structure and function and regulate the directional growth of SGN neurites are still facing severe challenges.In recent years,nanotechnology has been applied to promote the vigorous development of nerve regeneration to repair damaged nerve tissue.Among them,magnetic iron oxide nanoparticles(SPIO)have the characteristics of small particle size,good biocompatibility and superparamagnetism.It has been widely reported to promote the repair and regeneration of nerve cells in the fields of magnetic heat of tumors,drug delivery and other biomedical fields.Magnetic field(MF)is a recognized complementary medical tool,which can improve the body's life activities by regulating the metabolism of individual cells.It can also promote bone regeneration and regulate cell growth and differentiation.However,whether the synergistic effect of SPIO and magnetic field can affect the structure and function of SGN is still unclear.In this study,we used spiral ganglion neurons as experimental models to investigate the effects of different magnetic fields and SPIO on the morphological structure and function of SGN neurites.We found that the SPIO prepared by co-precipitation based magneto-endothermic method has better superparamagnetism,shape,hydrodynamic distribution and so on.Meanwhile,SPIO can effectively label SGN without affecting the cell activity of SGN,and obviously promote the growth of SGN neurites while achieving the tracing effect.In addition,the SGN labeled with SPIO can respond positively to the magnetic field and grow preferentially along the direction of the magnetic field,and further promote the growth and development of SGN.In conclusion,we found that SPIO and MF can promote the growth and development of SGN and induce the directional growth of SGN.Our study provides a theoretical and experimental basis for clinical application of SPIO and magnetic field to promote SGN regeneration to treat inductive deafness.