Acid-Degradable Polyurethane Particles for Protein-Based Vaccines: Biological Evaluation and in Vitro Analysis of Particle Degradation Products

Abstract

Acid-degradable particles containing a model protein antigen, ovalbumin, were prepared from a polyurethane with acetal moieties embedded throughout the polymer, and characterized by dynamic light scattering and transmission electron microscopy. The small molecule degradation by-product of the particles was synthesized and tested in vitro for toxicity indicating an LC50 of 12,500 μg/ml. A new liquid chromatography-mass spectrometry technique was developed to monitor the in vitro degradation of these particles. The degradation by-product inside RAW macrophages was at its highest level after 24 hours of culture and was efficiently exocytosed until it was no longer detectable after four days. When tested in vitro, these particles induced a substantial increase in the presentation of the immunodominant ovalbumin-derived peptide SIINFEKL in both macrophages and dendritic cells. In addition, vaccination with these particles generated a cytotoxic T-lymphocyte response that was superior to both free ovalbumin and particles made from an analogous but slower-degrading acid-labile polyurethane polymer. Overall, we present a fully degradable polymer system with non-toxic by-products, which may find use in various biomedical applications including protein-based vaccines.

Intracellular Delivery of a Protein Antigen with an Endosomal-Releasing Polymer Enhances CD8 T-Cell Production and Prophylactic Vaccine Efficacy

“…Previous studies have employed pH-responsive degradable elements based on poly(y-glutamic acid)-poly(L-phenylalanine ethyl ester)(26, 27), and acid labile particles and microgels that degrade at endosomal pH(28–31). However, pH-responsive polymeric carriers that actively alter vesicular trafficking pathways and promote endosomal escape of protein or peptide antigens have not been previously explored.…”

Redox-responsive nanocapsules for intracellular protein delivery

“…This result also demonstrates that during storage and assay of the CP-3 S-S NCs, no significant diffusion of CP-3 across the polymer matrix, or spontaneous reduction of the S-S crosslinker occurs. When the degradation of the polymer shell was 52 triggered by addition of GSH, CP-3 activity was readily observed and the rate of proteolysis was linearly correlated with the amount of reducing agent present. In the presence of 2 mM GSH, complete digestion of the substrate can be observed within one hour.…”

Sustained Delivery of Doxorubicin via Acetalated Dextran Scaffold Prevents Glioblastoma Recurrence after Surgical Resection

“…32, 33 This reaction generates acyclic and cyclic acetals on the pendent hydroxyl groups of dextran in a time-dependent manner. 34–36 The ratio between cyclic and acyclic acetals can be changed based on the length of reaction time. 34–36 Under aqueous conditions, acetal groups are hydrolyzed, revealing the parent hydroxyl groups of dextran and resulting in Ace-DEX degradation.…”

“…34–36 The ratio between cyclic and acyclic acetals can be changed based on the length of reaction time. 34–36 Under aqueous conditions, acetal groups are hydrolyzed, revealing the parent hydroxyl groups of dextran and resulting in Ace-DEX degradation. Since cyclic acetals are significantly more stable to hydrolysis than acyclic acetals, the time-dependent nature of acetal coverage allows for tight control of Ace-DEX degradation rate.…”