title: Polyelectrolyte Complexes of Low Molecular Weight PEI and Citric Acid as Efficient and Nontoxic Vectors for in Vitro and in Vivo Gene Delivery.
abstract: Gene transfection mediated by the cationic polymer polyethylenimine (PEI) is considered a standard methodology. However, while highly branched PEIs form smaller polyplexes with DNA that exhibit high transfection efficiencies, they have significant cell toxicity. Conversely, low molecular weight PEIs (LMW-PEIs) with favorable cytotoxicity profiles display minimum transfection activities as a result of inadequate DNA complexation and protection. To solve this paradox, a novel polyelectrolyte complex was prepared by the ionic cross-linking of branched 1.8 kDa PEI with citric acid (CA). This system synergistically exploits the good cytotoxicity profile exhibited by LMW-PEI with the high transfection efficiencies shown by highly branched and high molecular weight PEIs. The polyectrolyte complex (1.8 kDa-PEI@CA) was obtained by a simple synthetic protocol based on the microwave irradiation of a solution of 1.8 kDa PEI and CA. Upon complexation with DNA, intrinsic properties of the resulting particles (size and surface charge) were measured and their ability to form stable polyplexes was determined. Compared with unmodified PEIs the new complexes behave as efficient gene vectors and showed enhanced DNA binding capability associated with facilitated intracellular DNA release and enhanced DNA protection from endonuclease degradation. In addition, while transfection values for LMW-PEIs are almost null, transfection efficiencies of the new reagent range from 2.5- to 3.8-fold to those of Lipofectamine 2000 and 25 kDa PEI in several cell lines in culture such as CHO-k1, FTO2B hepatomas, L6 myoblasts, or NRK cells, simultaneously showing a negligible toxicity. Furthermore, the 1.8 kDa-PEI@CA polyelectrolyte complexes retained the capability to transfect eukaryotic cells in the presence of serum and exhibited the capability to promote in vivo transfection in mouse (as an animal model) with an enhanced efficiency compared to 25 kDa PEI. Results support the polyelectrolyte complex of LMW-PEI and CA as promising generic nonviral gene carriers.
authors: Department of Biochemistry and Molecular Biology II, School of Pharmacy, and ‡Department of Organic Chemistry, Biotechnology Institute, §Department of Analytical Chemistry, and ⊥Biocolloid and Fluid Physics Group, Department of Applied Physics, Faculty of Sciences, University of Granada , E-18071 Granada, Spain.
authors: M Dolores
authors: MD
authors: Giron-Gonzalez
authors: Department of Biochemistry and Molecular Biology II, School of Pharmacy, and ‡Department of Organic Chemistry, Biotechnology Institute, §Department of Analytical Chemistry, and ⊥Biocolloid and Fluid Physics Group, Department of Applied Physics, Faculty of Sciences, University of Granada , E-18071 Granada, Spain.
authors: Rafael
authors: R
authors: Salto-Gonzalez
authors: Department of Biochemistry and Molecular Biology II, School of Pharmacy, and ‡Department of Organic Chemistry, Biotechnology Institute, §Department of Analytical Chemistry, and ⊥Biocolloid and Fluid Physics Group, Department of Applied Physics, Faculty of Sciences, University of Granada , E-18071 Granada, Spain.
authors: F Javier
authors: FJ
authors: Lopez-Jaramillo
authors: Department of Biochemistry and Molecular Biology II, School of Pharmacy, and ‡Department of Organic Chemistry, Biotechnology Institute, §Department of Analytical Chemistry, and ⊥Biocolloid and Fluid Physics Group, Department of Applied Physics, Faculty of Sciences, University of Granada , E-18071 Granada, Spain.
authors: Alfonso
authors: A
authors: Salinas-Castillo
authors: Department of Biochemistry and Molecular Biology II, School of Pharmacy, and ‡Department of Organic Chemistry, Biotechnology Institute, §Department of Analytical Chemistry, and ⊥Biocolloid and Fluid Physics Group, Department of Applied Physics, Faculty of Sciences, University of Granada , E-18071 Granada, Spain.
authors: Ana Belen
authors: AB
authors: Jodar-Reyes
authors: Department of Biochemistry and Molecular Biology II, School of Pharmacy, and ‡Department of Organic Chemistry, Biotechnology Institute, §Department of Analytical Chemistry, and ⊥Biocolloid and Fluid Physics Group, Department of Applied Physics, Faculty of Sciences, University of Granada , E-18071 Granada, Spain.
authors: Mariano
authors: M
authors: Ortega-Muñoz
authors: Department of Biochemistry and Molecular Biology II, School of Pharmacy, and ‡Department of Organic Chemistry, Biotechnology Institute, §Department of Analytical Chemistry, and ⊥Biocolloid and Fluid Physics Group, Department of Applied Physics, Faculty of Sciences, University of Granada , E-18071 Granada, Spain.
authors: Fernando
authors: F
authors: Hernandez-Mateo
authors: Department of Biochemistry and Molecular Biology II, School of Pharmacy, and ‡Department of Organic Chemistry, Biotechnology Institute, §Department of Analytical Chemistry, and ⊥Biocolloid and Fluid Physics Group, Department of Applied Physics, Faculty of Sciences, University of Granada , E-18071 Granada, Spain.
authors: Francisco
authors: F
authors: Santoyo-Gonzalez
mesh_terms: D002460:Cell Line; D019343:Citric Acid / Q000737:chemistry*; D004573:Electrolytes / Q000737:chemistry*; D006801:Humans; D066298:In Vitro Techniques; D008970:Molecular Weight; D011094:Polyethyleneimine / Q000737:chemistry*; D014162:Transfection
chemical_list: D004573:Electrolytes; D019343:Citric Acid; D011094:Polyethyleneimine