title: Immobilized concentration gradients of nerve growth factor guide neurite outgrowth.
abstract: Axons are guided to their targets by a combination of haptotactic and chemotactic cues. We previously demonstrated that soluble neurotrophic factor concentration gradients guide axons in a model system. In an attempt to translate this model system to a device for implantation, our goal was to immobilize a stable neurotrophic concentration gradient for axonal (or neurite) guidance. Nerve growth factor (NGF) was immobilized within poly(2-hydroxyethylmethacrylate) [p(HEMA)] microporous gels using a gradient maker. The NGF was stably immobilized, with only approximately 0.05% of the amount originally incorporated into the gel released over an 8-day period. Immobilized NGF was bioactive: the percent of PC12 cells extending neurites on NGF-immobilized p(HEMA) gels was 16 +/- 2%, which was statistically the same as those exposed to soluble NGF (22 +/- 6%). We were able to predict and reproducibly create stable NGF concentration gradients in the gel. At an NGF concentration gradient of 357 ng/mL/mm, PC12 cell neurites were guided up the gradient. The facile, flexible, and reproducible nature of this method allowed us to translate soluble growth factor gradient models to stable growth factor gradient devices that may ultimately enhance axonal guidance and regeneration in vivo.
authors.affiliation: University of Toronto, Department of Chemical Engineering and Applied Chemistry, 200 College Street, Toronto ON Canada M5S 3E5.
authors.forename: Terri Adams
authors.initials: TA
authors.lastname: Kapur
authors.forename: Molly S
authors.initials: MS
authors.lastname: Shoichet
mesh_terms: D000818:Animals; D018929:Cell Culture Techniques / Q000295:instrumentation / Q000379:methods; D003470:Culture Media; D004305:Dose-Response Relationship, Drug; D008856:Microscopy, Fluorescence; D020932:Nerve Growth Factor / Q000494:pharmacology*; D016501:Neurites / Q000187:drug effects*; D016716:PC12 Cells; D011102:Polyhydroxyethyl Methacrylate; D051381:Rats
chemical_list: D003470:Culture Media; D011102:Polyhydroxyethyl Methacrylate; D020932:Nerve Growth Factor