PEGylated Cationic Polylactides for Hybrid Biosynthetic Gene Delivery

Genetic vaccination is predicated on the underlying principle that diseases can be prevented by the controlled introduction of genetic material encoding antigenic proteins from pathogenic organisms to elicit the formation of protective immune responses. Driving this process is the choice of carrier that is responsible for navigating the obstacles associated with gene delivery. In this work, we expand upon a novel class of hybrid biosynthetic gene delivery vectors that are composed of a biomaterial outer coating and a bacterial (<i>Escherichia coli</i>) inner core. Specifically, a series of newly developed biodegradable cationic polylactides (CPLAs) and their PEGylated variants were selected to investigate the role of low polydispersity index (PDI), charge density, and PEGylation upon hybrid vector assembly and gene delivery efficacy. Upon assembly, hybrid vectors mediated increased gene delivery beyond that of the individual bacterial vector in isolation, including assays with increasing medium protein content to highlight shielding properties afforded by the PEG-functionalized CPLA component. Furthermore, after extensive characterization of surface deposition of the polymer, results prompted a new model for describing hybrid vector assembly that includes cellular coating and penetration of the CPLA component. In summary, these results provide new options and insight toward the assembly and application of next-generation hybrid biosynthetic gene delivery vectors

Structure–Function Assessment of Mannosylated Poly(β-amino esters) upon Targeted Antigen Presenting Cell Gene Delivery

Antigen presenting cell (APC) gene delivery is a promising avenue for modulating immunological outcomes toward a desired state. Recently, our group developed a delivery methodology to elicit targeted and elevated levels of APC-mediated gene delivery. During these initial studies, we observed APC-specific structure–function relationships with the vectors used during gene delivery that differ from current non-APC cell lines, thus, emphasizing a need to re-evaluate vector-associated parameters in the context of APC gene transfer. Thus, we describe the synthesis and characterization of a second-generation mannosylated poly­(β-amino ester) library stratified by molecular weight. To better understand the APC-specific structure–function relationships governing polymeric gene delivery, the library was systematically characterized by (1) polymer molecular weight, (2) relative mannose content, (3) polyplex biophysical properties, and (4) gene delivery efficacy. In this library, polymers with the lowest molecular weight and highest relative mannose content possessed gene delivery transfection efficiencies as good as or better than commercial controls. Among this group, the most effective polymers formed the smallest polymer-plasmid DNA complexes (∼300 nm) with moderate charge densities (<10 mV). This convergence in polymer structure and polyplex biophysical properties suggests a unique mode of action and provides a framework within which future APC-targeting polymers can be designed