Confinement of Therapeutic Enzymes in Selectively Permeable Polymer Vesicles by Polymerization-Induced Self-Assembly (PISA) Reduces Antibody Binding and Proteolytic Susceptibility

Abstract

Covalent PEGylation of biologics has been widely employed to reduce immunogenicity, while improving stability and half-life in vivo. This approach requires covalent protein modification, creating a new entity. An alternative approach is stabilization by encapsulation into polymersomes; however this typically requires multiple steps, and the segregation requires the vesicles to be permeable to retain function. Herein, we demonstrate the one-pot synthesis of therapeutic enzyme-loaded vesicles with size-selective permeability using polymerization-induced self-assembly (PISA) enabling the encapsulated enzyme to function from within a confined domain. This strategy increased the proteolytic stability and reduced antibody recognition compared to the free protein or a PEGylated conjugate, thereby reducing potential dose frequency and the risk of immune response. Finally, the efficacy of encapsulated l-asparaginase (clinically used for leukemia treatment) against a cancer line was demonstrated, and its biodistribution and circulation behavior in vivo was compared to the free enzyme, highlighting this methodology as an attractive alternative to the covalent PEGylation of enzymes.

Predicting Monomers for Use in Polymerization‐Induced Self‐Assembly

“…Polymer nanoparticles obtained from PISA have applications in nanomedicine and drug delivery, [6] especially in the case of worm or vesicle morphologies,w hich have specific advantages over spherical micelles.I np articular,t hese morphologies often have higher loading capacities than spherical micelles and different in vivo cell adsorption and internalization behavior. [7] In the case of polymeric vesicles, both hydrophobic and hydrophilic payloads can be encapsulated due to the fact that they possess both av esicle membrane and an aqueous interior.…”

Controlling Nanomaterial Size and Shape for Biomedical Applications via Polymerization‐Induced Self‐Assembly

“…After confirming the permeability of the PEG‐ b ‐PHPMA vesicle membrane and demonstrating successful enzyme encapsulation, Blackman et al. also studied the encapsulation of a commercially available protein therapeutic, l ‐asparaginase (ASNS) . Proteins such as ASNS are usually covalently PEGylated, which modifies the protein's hydrophobicity and surface charge .…”

“…Due to these unique properties, nanoworms have recently attracted considerable interest in a variety of different fields including catalysis, material science, immunology, tissue engineering, and drug delivery . In addition to nanoworms, amphiphilic block copolymer vesicle structures or polymersomes have been commonly exploited for biomedical applications . Hence, this review will focus on the biomedical applications of spherical micelles, worm‐like micelles, and vesicles.…”

Bioactive Peptide Brush Polymers via Photoinduced Reversible‐Deactivation Radical Polymerization

“…We reasoned that these mild conditions should provide a route for the incorporation of peptide‐modified vinyl monomers into bioactive, highly functionalized polymers, and polymeric materials. The mild conditions would minimize side reactions and thus retain the integrity of the biomolecules during polymerization and provide clean materials following polymerization …”