title: Enhanced neurotrophin-3 bioactivity and release from a nanoparticle-loaded composite hydrogel.
abstract: Neurotrophin-3 (NT-3) has shown promise in regenerative strategies after spinal cord injury; however, sustained local delivery is difficult to achieve by conventional methods. Controlled release from poly(lactic-co-glycolic acid) (PLGA) nanoparticles has been studied for numerous proteins, yet achieving sustained release of bioactive proteins remains a challenge. To address these issues, we designed a composite drug delivery system comprised of NT-3 encapsulated in PLGA nanoparticles dispersed in an injectable hydrogel of hyaluronan and methyl cellulose (HAMC). A continuum model was used to fit the in vitro release kinetics of an NT-3 analog from a nanoparticle formulation. Interestingly, the model suggested that the linear drug release observed from composite HAMC was due to a diffusion-limiting layer of methyl cellulose on the particle surface. We then studied the effects of processing parameters and excipient selection on NT-3 release, stability, and bioactivity. Trehalose was shown to be the most effective additive for stabilizing NT-3 during sonication and lyophilization and PLGA itself was shown to stabilize NT-3 during these processes. Of four excipients tested, 400g/mol poly(ethylene glycol) was the most effective during nanoparticle fabrication, with 74% of NT-3 detected by ELISA. Conversely, co-encapsulation of magnesium carbonate with NT-3 was the most effective in maintaining NT-3 bioactivity over 28 days according to a cell-based axonal outgrowth assay. Together, the modeling and optimized processing parameters provide insight critical to designing a controlled bioactive release formulation for ultimate testing in vivo.
authors.affiliation: Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, ON, Canada M5S 3E5.
authors.forename: Jason C
authors.initials: JC
authors.lastname: Stanwick
authors.forename: M Douglas
authors.initials: MD
authors.lastname: Baumann
authors.forename: Molly S
authors.initials: MS
authors.lastname: Shoichet
mesh_terms: D000818:Animals; D004622:Embryo, Mammalian; D005260:Female; D005727:Ganglia, Spinal / Q000187:drug effects* / Q000254:growth & development; D006801:Humans; D006820:Hyaluronic Acid / Q000008:administration & dosage / Q000737:chemistry; D020100:Hydrogels / Q000008:administration & dosage* / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D019344:Lactic Acid / Q000008:administration & dosage / Q000737:chemistry; D008274:Magnesium / Q000008:administration & dosage / Q000737:chemistry; D008747:Methylcellulose / Q000008:administration & dosage / Q000737:chemistry; D053758:Nanoparticles / Q000008:administration & dosage* / Q000737:chemistry; D016501:Neurites / Q000187:drug effects / Q000502:physiology; D020933:Neurotrophin 3 / Q000008:administration & dosage* / Q000737:chemistry; D011100:Polyglycolic Acid / Q000008:administration & dosage / Q000737:chemistry; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D051381:Rats; D017207:Rats, Sprague-Dawley; D011994:Recombinant Proteins / Q000008:administration & dosage / Q000737:chemistry
chemical_list: D020100:Hydrogels; D020933:Neurotrophin 3; D011994:Recombinant Proteins; C005479:magnesium carbonate; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid; D006820:Hyaluronic Acid; D008747:Methylcellulose; D008274:Magnesium