The Effect Of Electric Fields On Neurite Guidance Of Spiral Ganglion Neurons In Vitro

Partâ… Study on the construction of neurite guidance system of spiral ganglion neurons by electric fields in vitroObjectives: To establish a neurite guidance system of spiral ganglion neurons by electric fields in ivtro.Methods: The spiral ganglion of postnatal day 4-6 Sprague-Dawley rats were dissected out. Spiral ganglion neurons were cultured by dissociated culture method or explants culture method. The coating materials included Laminin, PDL, PDL plus Laminin, Collagen I and none. The antibody of Neurofilament, MAP2 and Tau-1 were used to identify the neurite of spiral ganglion neurons. The systems of electric fields were constructed by inducing Pt-Ir wires, rings or electrode array, which were differently connected with steady DC power, Function/Arbitrary waveform generator or Cochlear Implant signal processor. The traces of growth cones were recorded by taking photos just before and after the electric stimulus in a CO₂ incubator or by time lapse module in live cell imaging (LCI) system after transplanting culture.Results: It was much easier for the neurites of spiral ganglion neurons to become "free" neurites without interference by surrounding cells in explants culture system than that in dissociated culture system. More neurites were found on slices coating with Laminin, PDL or PDL plus Laminin than on ones coating with Collagen I and none. The neurites could be labeled by the antibody of Neurofilament and Tau-1, but not by the antibody of MAP2. The method of time lapse recording in LCI system after transplanting culture was helpful to maintain a steady environment for neurite extending. Furthermore, it made the orientation of neurites in electric fields much easy, which is essential to the investigation on neurite guidance and helpful to improve investigation efficiency.Conclusions: Explants culture on slices coating with Laminin, PDL or PDL plus Laminin is suitable for neurite guidance investigation on spiral ganglion neurons. Transplanting culture and time lapse recording in LCI system is helpful to an efficient investigation on neurite guidance of spiral ganglion neurons by electric fields. Partâ…¡The effect of steady and pulsed electric fields on the neurite growth direction of spiral ganglion neurons in vitroObjectives: To investigate the effect of steady and pulsed electric fields on neurite growth direction of spiral ganglion neurons in vitro.Methods: The spiral ganglion neurons were cultured on slices coated with Laminin or PDL by explants culture. The slices with "free neurite" were transplanted into LCI system with the direction of neurite terminals perpendicular to the vector in parallel-electrodes electric fields. The locations of growth cones in different time were recorded by taking photos. The turning angles were measured in different culture systems with no electric fields, steady or pulsed 100mV/mm DC electric fields.Results: The neurites cultured on Laminin coated slices turned to the cathode by steady and pulsed 100mV/mm DC electric fields, while the neurites cultured on PDL coated slices turned to the anode. The neurites extended almost straightly in culture systems without electric field.Conclusions: Steady and pulsed DC electric fields could both steer the direction of neurite extension of spiral ganglion neurons. Furthermore, the directions were different on slices coated with different materials.Partâ…¢The effect of charged-balanced biphasic pulsed electric fields on the neurite growth direction of spiral ganglion neurons in vitroObjectives: To investigate the effect of charged-balanced biphasic pulsed electric fields on the neurite growth direction of spiral ganglion neurons in vitro.Methods: The spiral ganglion neurons were cultured on slices coated with Laminin by explants culture. The slices with "free neurite" were transplanted into LCI system with the direction of neurite terminals parallel to the line of two ring electrodes. The distance between the two electrodes (D) was 2 mm. The growth cones were oriented on the location 1 mm (1/2D), 2 mm (D) and 4 mm (2D) away to one of the electrodes. And the growth cones 2 mm (D) away to one of the electrodes in culture system without electric fields were also investigated as a contrast. The traces of growth cones were recorded by taking photos, which followed by turning angles measurement.Results: The neurites 1 mm (1/2D), 2 mm (D) and 4 mm (2D) away to the electrodes turned off the electrodes, while the directions of neurites in culture systems without electric field had no obvious tendency.Conclusions: The neurites of spiral ganglion neurons in charged-balanced biphasic pulsed electric fields had a tendency to turn away from the electrodes in vitro.