A comparative evaluation of poly-l-lysine-palmitic acid and Lipofectamine ™ 2000 for plasmid delivery to bone marrow stromal cells

The current study compared the effectiveness of an amphiphilic biomaterial poly(l-lysine)-palmitic acid (PLL–PA), and the lipid-based transfection agent Lipofectamine™ 2000 for plasmid delivery to bone marrow stromal cells (BMSC). We investigated the utility of the carriers to deliver a plasmid containing enhanced green fluorescent protein (pEGFP) to BMSC in vitro. Confocal microscopy was used to investigate the intracellular trafficking of pEGFP/carrier complexes. pEGFP delivery and EGFP expression were assessed by flow cytometry. PLL–PA formed condensed structures with pEGFP and successfully delivered the plasmid into the nucleus within 5 h of incubation with the cells. PLL–PA delivered the pEGFP to 80% of the cells, achieving a maximum transfection efficiency of 22%. This was significantly higher than Lipofectamine™ 2000-mediated transfection, which was 11% under most optimal conditions. Dosing the BMSC two or three times during the 24 h period increased the transfection efficiency by 2–3 folds, without compromising cell viability. When chloroquine was employed as an ensomolytic agent, 100 μm of the drug increased the transfection efficiency while reducing cell viability, but lower concentrations (1–10 μm) were not beneficial for transfection. Combining PLL–PA with Lipofectamine™ 2000 created an additive effect, increasing the transfection efficiency of PLL–PA. Long-term evaluation of gene expression with pEGFP/PLL–PA yielded 17% transfection on day 1, which gradually decreased over a 12-day period. We conclude that PLL–PA is an effective biomaterial carrier and a promising candidate for non-viral gene delivery to BMSC.