(356e) Lipid–Polymer Hybrid Nanoparticles for mRNA Delivery

Long-term storage and sustained release of mRNA remain major challenges in the development of mRNA-based vaccines and therapeutics. Herein, we present a 'particle-in-particle' (PNP) nanostructure approach for gene delivery with biodegradable and sustained release properties. Briefly, a new class of lipid-modified polymer poly (β-amino esters) (L-PBAEs) is developed via enzyme-catalyzed esterification and further formulation of the L-PBAEs with poly(d,l-lactidecoglycolide)-b-poly(ethylene glycol) (PLGA-PEG) leads to self-assembly into a “particle-in-particle” (PNP) nanostructure for gene delivery. Out of 24 PNP candidates, the top-performing PNP/C12-PBAE nanoparticles efficiently deliver both DNA and mRNA in vitro and in vivo, presenting enhanced transfection efficacy, sustained gene release behavior, and excellent stability for at least 12 months of storage at −20 °C after lyophilization without loss of transfection efficacy. Encapsulated with spike encoded plasmid DNA and mRNA, the lipid-modified polymeric PNP COVID-19 vaccines successfully elicit spike-specific antibodies and Th1-biased T cell immune responses in immunized mice even after 12 months of lyophilized storage at −20 °C. This newly developed lipid-polymer hybrid PNP nanoparticle system demonstrates a new strategy for both plasmid DNA and mRNA delivery with the capability of long-term lyophilized storage. Additionally, we have explored the therapeutic potential of mRNA-encapsulated nanoparticles for the treatment of cancer and obesity. Our strategy represents a significant step toward developing a new gene delivery platform with biodegradable and controlled-release properties to address the urgent need for treatments against infectious and other diseases.