Size-controlled lipid nanoparticle production using turbulent mixing to enhance oral DNA delivery

Lipid-based nanoparticles (LNPs) have been developed to address the transport and uptake barriers to enhance the delivery efficiency of plasmid DNA therapeutics. In these systems, plasmid DNA can be encapsulated through condensation by a cationic lipid to form lipo-complexes, or polycation following complexation into cationic liposomes to form lipo-polyplexes. Conventional methods for achieving these two DNA-delivering LNP vehicles suffer from significant batch-to-batch variation, poor scalability and complicated multi-step preparation procedures. Resultant nanoparticles often have uncontrollable size and surface charge with wide distribution, and poor stability when exposed to physiological media. Here we report a single-step flash nanocomplexation (FNC) process using turbulent mixing to prepare uniform lipo-complex or lipo-polyplex LNPs in a scalable manner, demonstrating excellent control over the nanoparticle size (from 40 to several hundred nm) and surface charge, with narrow size distribution. The FNC-produced LNPs could be purified and concentrated using a tangential flow filtration (TFF) process in a scalable manner. An optimized formulation of purified lipo-complex LNPs (DOTAP/Chol/DNA, 45 nm) showed significantly higher (5-fold in the lungs and 4-fold in the liver) transgene expression activity upon oral dosage than lipo-polyplex LNPs (DPPC/Chol/lPEI/DNA, 75 nm) or lPEI/DNA nanoparticles (43 nm). Repeated dosing (4 days, 150 μg/day) of the lipo-complex LNPs sustained the transgene activity over a period of one week without detectable toxicity in major organs, suggesting its potential for clinical translation. STATEMENT OF SIGNIFICANCE: We report a new method to prepare uniform size-controlled lipid-based DNA-loaded nanoparticles by turbulent mixing delivered by a multi-inlet vortex mixer. Two distinct compositions were successfully prepared: (1) lipo-complexes, through condensation of the plasmid DNA by cationic lipids; (2) lipo-polyplexes, by encapsulation of DNA/PEI together with neutral lipids. Comparing with conventional methods, which use multi-step processes with high batch-to-batch variations and poor control over nanoparticle characteristics, this method offers a single-step, continuous and reproducible assembly methodology that would promote the translation of such gene medicine products. Effective purification and concentration of nanoparticles were achieved by adopted tangential flow filtration method. Following oral gavage in mice, the lipo-complex nanoparticles showed the highest level of transgene expression in the lung and liver.