Background: Successful nanoparticle delivery of gene-editing tools is dependent on the ability of nanoparticles to pass through the cellular membrane, move through the cytoplasm, and cross the nuclear envelope to enter the nucleus. It is critical that intracellular nanoparticles interact with the cytoskeletal network to move toward the nucleus and must escape degradation pathways including lysosomal digestion. Without efficient intracellular trafficking, nanoparticles loaded with gene editing tools cannot reach the nucleus for efficient transfection.
Objective: We have developed nanoparticles with a low molecular weight branched polyethylenimine lipid shell and PLGA core that can effectively deliver plasmid DNA to macrophages for gene editing while limiting toxicity.
Methods: Core-shell nanoparticles were synthesized by a modified solvent-evaporation method and were loaded with plasmid DNA. Confocal microscopy was used to visualize the internalization, intracellular distribution and cytoplasmic transportation of plasmid DNA loaded nanoparticles (pDNA-NPs) in bone marrow derived macrophages.
Results: Core-shell nanoparticles had a high surface charge of +56 mV and a narrow size distribution. When loaded with plasmid DNA for transfection, the nanoparticles increased in size from 150 nm to 200 nm, and the zeta potential decreased to +36 mV, indicating successful loading. Further, fluorescence microscopy revealed that pDNA-NPs crossed the cell membrane and interacted with actin filaments. Intracellular tracking of pDNA-NPs showed successful separation of pDNA-NPs from lysosomes, allowing entry into the nucleus at 2 hours, with further nuclear ingress up to 5 hours. Bone marrow derived macrophages treated with pDNA/GFP-NPs exhibited high GFP expression with low cytotoxicity.
Conclusions: Together, this data suggests pDNA-NPs are an effective delivery system for macrophage gene-editing.