Critical determinants in PLGA/PLA nanoparticle-mediated gene expression.

PURPOSE: The aim of the study was to determine the critical determinants in nanoparticle-mediated gene transfection. It was hypothesized that different formulation parameters could affect the nanoparticle characteristics and hence its gene transfection.
METHODS: Nanoparticles encapsulating plasmid DNA encoding for firefly luciferase were formulated using polylactide (PLA) and poly (D,L-lactide-co-glycolide) (PLGA) polymers of different compositions and molecular weights. A multiple-emulsion solvent-evaporation method with polyvinyl alcohol (PVA) as an emulsifier was used to formulate DNA-loaded nanoparticles. Gene expression of nanoparticles was determined in breast cancer (MCF-7) and prostate cancer (PC-3) cell lines.
RESULTS: Nanoparticles formulated using PLGA polymer demonstrated greater gene transfection than those formulated using PLA polymer, and this was attributed to the higher DNA release from PLGA nanoparticles. Higher-molecular-weight PLGA resulted in the formation of nanoparticles with higher DNA loading, which demonstrated higher gene expression than those formulated with lower-molecular-weight PLGA. In addition, the nanoparticles with lower amount of surface-associated PVA demonstrated higher gene transfection in both the cell lines. Higher gene transfection with these nanoparticles was attributed to their higher intracellular uptake and cytoplasmic levels. Further study demonstrated that the molecular weight and the degree of hydrolyzation of PVA used as an emulsifier also affect the gene expression of nanoparticles.
CONCLUSIONS: Results thus demonstrate that the DNA loading in nanoparticles and its release, and the surface-associated PVA influencing the intracellular uptake and endolysosomal escape of nanoparticles, are some of the critical determinants in nanoparticle-mediated gene transfection.