Transfecting the hard-to-transfect lymphoma/leukemia cells using a simple cationic polymer nanocomplex

Although the development of gene delivery systems via non-viral-mediated methods is advancing rapidly, it remains a challenge to deliver plasmids into hard-to-transfect cells, such as lymphoma/leukemia cells. To develop an efficient transfection method, we formulated a simple nanocomplex by incorporating poly β-amino ester (PBAE) polymers with plasmid DNAs containing a GFP reporter gene. The formed PBAE-plasmid nanocomplexes are approximately 200 nm in diameter and stable under physiological conditions, but become rapidly biodegradable when pH decreases < 7.0. Cultured lymphoma/leukemia cells were used for transfection assays and resultant gene delivery rates were determined by quantifying GFP expression. Exposure of cells to the nanocomplexes composed of fractioned PBAE (> 7 kDa) resulted in GFP expression in 3% of cells, similar to that mediated by the standard Lipofectamine method. However, with polybrene pre-treatment, the nanocomplex could achieve GFP expression in up to 32% of lymphoma/leukemia cells, an 8-fold increase over that mediated by Lipofectamine. These findings demonstrated a simple, efficient method for in vitro gene delivery into hard-to-transfect cells. The nanocomplexes are biodegradable and have minimal cytotoxicity, suggesting the potential use for in vivo gene delivery.