title: Intracellular calcium and cyclic nucleotide levels modulate neurite guidance by microtopographical substrate features.
abstract: Micro- and nanoscale surface features have emerged as potential tools to direct neurite growth into close proximity with next generation neural prosthesis electrodes. However, the signaling events underlying the ability of growth cones to respond to topographical features remain largely unknown. Accordingly, this study probes the influence of [Ca(2+) ]i and cyclic nucleotide levels on the ability of neurites from spiral ganglion neurons (SGNs) to precisely track topographical micropatterns. Photopolymerization and photomasking were used to generate micropatterned methacrylate polymer substrates. Dissociated SGN cultures were plated on the micropatterned surfaces. Calcium influx and release from internal stores were manipulated by elevating extracellular K(+) , maintenance in calcium-free media, or bath application of various calcium channel blockers. Cyclic nucleotide activity was increased by application of cpt-cAMP or 8-Br-cGMP. Elevation of [Ca(2+) ]i by treatment of cultures with elevated potassium reduced neurite alignment to physical microfeatures. Maintenance of cultures in Ca(2+) -free medium or treatment with the non-selective voltage-gated calcium channel blocker cadmium or L-type Ca(2+) channel blocker nifedipine did not signficantly alter SGN neurite alignment. By contrast, ryanodine or xestospongin C, which block release of internal calcium stores via ryanodine-sensitive channels or inositol-1,4,5-trisphosphate receptors respectively, each significantly decreased neurite alignment. Cpt-cAMP significantly reduced neurite alignment while 8-Br-cGMP significantly enhanced neurite alignment. Manipulation of [Ca(2+) ]i or cAMP levels significantly disrupts neurite guidance while elevation of cGMP levels increases neurite alignment. The results suggest intracellular signaling pathways similar to those recruited by chemotactic cues are involved in neurite guidance by topographical features. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2037-2048, 2016.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, University of Iowa, Iowa City, Iowa, 52242.|Department of Otolaryngology, Eye & ENT Hospital of Fudan University, Shanghai, 200031, China.
authors.forename: Shufeng
authors.initials: S
authors.lastname: Li
authors.affiliation: Department of Chemical and Biochemical Engineering, University of Iowa, Iowa City, Iowa, 52242.
authors.forename: Bradley
authors.initials: B
authors.lastname: Tuft
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, University of Iowa, Iowa City, Iowa, 52242.
authors.forename: Linjing
authors.initials: L
authors.lastname: Xu
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, University of Iowa, Iowa City, Iowa, 52242.
authors.forename: Marc
authors.initials: M
authors.lastname: Polacco
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, University of Iowa, Iowa City, Iowa, 52242.
authors.forename: Joseph C
authors.initials: JC
authors.lastname: Clarke
authors.affiliation: Department of Chemical and Biochemical Engineering, University of Iowa, Iowa City, Iowa, 52242.
authors.forename: C Allan
authors.initials: CA
authors.lastname: Guymon
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, University of Iowa, Iowa City, Iowa, 52242.|Department of Neurosurgery, University of Iowa, Iowa City, Iowa, 52242.
authors.forename: Marlan R
authors.initials: MR
authors.lastname: Hansen
mesh_terms: D000818:Animals; D000071437:Axon Guidance / Q000187:drug effects; D002118:Calcium / Q000378:metabolism*; D002470:Cell Survival / Q000187:drug effects; D000242:Cyclic AMP / Q000378:metabolism*; D006152:Cyclic GMP / Q000378:metabolism*; D042541:Intracellular Space / Q000378:metabolism*; D047028:Macrocyclic Compounds / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects; D010080:Oxazoles / Q000494:pharmacology; D011108:Polymers / Q000737:chemistry; D051381:Rats; D012433:Ryanodine / Q000494:pharmacology; D013136:Spiral Ganglion / Q000166:cytology
chemical_list: D047028:Macrocyclic Compounds; D010080:Oxazoles; D011108:Polymers; C511704:xestospongin C; D012433:Ryanodine; D000242:Cyclic AMP; D006152:Cyclic GMP; D002118:Calcium
keywords: calcium; cyclic nucleotide; micropatterning; nerve guide; photopolymerization; spiral ganglion neuron; surface topography