Tuning DLVO Interactions Alters Polymer-Mediated pDNA Delivery in a Cell Type-Dependent Manner.

Area of Science:

• Colloidal science
• Biomaterials science
• Gene delivery

Background:

• Polycations are crucial for binding, protecting, and delivering nucleic acids like plasmid DNA (pDNA).
• The size of polycation-pDNA complexes (polyplexes) significantly influences gene expression, cell viability, and cellular uptake.
• Decoupling polyplex size from polycation composition has been a challenge in gene delivery research.

Purpose of the Study:

• To systematically map the size preferences of polyplexes for various cell types.
• To apply colloidal science principles to create compositionally equivalent polyplexes of varying sizes.
• To investigate the relationship between polyplex size, pDNA condensation, cellular internalization, and gene delivery outcomes.

Main Methods:

• Generated polyplexes with hydrodynamic radii ranging from 40 to 827 nm by controlling interpolyplex interactions.
• Utilized Derjaguin-Landau-Verwey-Overbeek (DLVO) analysis to guide pH and ionic strength selection for controlled aggregation.
• Employed kinetic control of polyplex aggregation via pH changes at specific time points to arrest size.
• Quantified pDNA loading using static light scattering and assessed transgene expression in kidney cells, retinal cells, and macrophages.

Main Results:

• Successfully generated polyplexes across a wide size range (40-827 nm) with controlled composition.
• Observed looser pDNA packing in larger polyplexes (increased hydrodynamic volume).
• Demonstrated cell-type-specific polyplex size preferences, with kidney cells favoring 85-136 nm and retinal cells tolerating 85-349 nm.
• Identified size-dependent cellular internalization as a key factor limiting pDNA delivery efficiency.
• Showed that polyplex size tuning can balance toxicity and transfection efficiency.

Conclusions:

• Colloidal science principles enable precise control over polyplex size, independent of polycation composition.
• Polyplex size is a critical determinant of gene delivery efficiency and toxicity, varying significantly between cell types.
• Optimizing polyplex size offers a strategy to enhance polymer-mediated pDNA delivery and overcome cellular barriers.