PEI Transfection Reagent

Researchers employed a low-cost, high-efficiency transfection method using linear 25 kDa polyethylenimine (PEI) to generate recombinant adeno-associated virus (rAAV) vectors in mammalian cells. In contrast to calcium-phosphate or commercial lipid reagents, linear PEI yields ≥ 90% EGFP-positive HeLa or XDC293 cells, exhibits low variability, and is serum-tolerant.
When used with a typical triple-plasmid AAV system, linear-PEI-transfected E1A-negative HeLa cells generated 3-fold more infectious rAAV than PEI-transfected XDC293 cells and 7-fold more than calcium-phosphate-transfected XDC293 cells, as measured by transduction and qPCR assays.

Fig. 1 Effect on varying N/P ratio of linear PEI on transfection of XDC293 cells and Hela cells with pEGFP-N1. (Reed S E.; et al. 2006)

PEI's high cationic-charge density condenses chemotherapeutics and nucleic acids (siRNA, shRNA, pDNA) into stable nanoparticles that evade drug-resistance pumps, enhance tumor uptake via endocytosis, and release payloads in response to acidic pH or redox conditions. Linear and low-MW PEI exhibit superior transfection with lower cytotoxicity than branched analogs. Surface shielding with PEG, HA, or targeted ligands further improves circulation time and specificity.
More than 30 recent in-vitro and in-vivo studies were analyzed. PEI-based systems co-delivering doxorubicin plus Bcl-2 siRNA, docetaxel plus TRAIL plasmid, or gemcitabine plus NF-κB siRNA consistently show synergistic apoptosis, reduced tumor volume, and decreased systemic toxicity in TNBC, MCF-7 and MDA-MB-231 models.

Fig. 2 Mechanism of action of PEI for drug and nucleic acid internalization via endocytosis. (Fahira A I.; et al. 2023)