methylcellulose and magnesium-carbonate

Anti-NogoA is a promising anti-inhibitory molecule that has been shown to enhance functional recovery after spinal cord injury when delivered in rat and primate models over the span of weeks. To achieve this sustained release, anti-NogoA is typically delivered by osmotic minipumps; however, external minipumps are susceptible to infection. To address this issue, we developed a drug delivery system that consists of anti-NogoA-loaded poly(lactic-co-glycolic acid) nanoparticles dispersed in a hydrogel of hyaluronan and methylcellulose (composite HAMC). To optimize in vitro release, we screened formulations for improved anti-NogoA bioactivity and sustained release based on combinations of co-encapsulated trehalose, hyaluronan, MgCO(3), and CaCO(3). Co-encapsulated MgCO(3) and CaCO(3) slowed the rate of anti-NogoA release and did not influence anti-NogoA bioactivity. Co-encapsulated trehalose significantly improved anti-NogoA bioactivity at early release time points by stabilizing the protein during lyophilization. Co-encapsulated trehalose with hyaluronan improved bioactivity up to 28d and dramatically increased the rate and duration of sustained delivery. The sustained release of bioactive anti-NogoA from composite HAMC is a compelling formulation for in vivo evaluation in a model of spinal cord injury.

Topics: Antibodies, Monoclonal; Calcium Carbonate; Chemistry, Pharmaceutical; Delayed-Action Preparations; Drug Carriers; Drug Compounding; Drug Stability; Enzyme-Linked Immunosorbent Assay; Excipients; Freeze Drying; Hyaluronic Acid; Hydrogels; Kinetics; Lactic Acid; Magnesium; Methylcellulose; Myelin Proteins; Nanoparticles; Nanotechnology; Nogo Proteins; Polyglycolic Acid; Polylactic Acid-Polyglycolic Acid Copolymer; Polymers; Solubility; Spinal Cord Injuries; Technology, Pharmaceutical; Trehalose

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.

Topics: Animals; Embryo, Mammalian; Female; Ganglia, Spinal; Humans; Hyaluronic Acid; Hydrogels; Hydrogen-Ion Concentration; Lactic Acid; Magnesium; Methylcellulose; Nanoparticles; Neurites; Neurotrophin 3; Polyglycolic Acid; Polylactic Acid-Polyglycolic Acid Copolymer; Rats; Rats, Sprague-Dawley; Recombinant Proteins