title: Optimized lipopolyplex formulations for gene transfer to human colon carcinoma cells under in vitro conditions.
abstract: BACKGROUND
  Polycation (PC, polyplex), cationic lipid (CL, lipoplex), and a combination of PC/CL (lipopolyplex) formulations were investigated for gene transfer to slow-proliferating human colon carcinoma cell lines (COGA).
  
  
  METHODS
  The luciferase reporter gene was complexed with either PC, CL, or PC/CL. PCs included linear (PEI22lin, 22 kDa) and branched polyethylenimine (PEI2k, 2 kDa; PEI25br, 25 kDa) and poly-L-lysine (PLL18 with 18 lysine monomers). CLs included DOCSPER, DOSPER and DOTAP. Lipopolyplexes were formed by either sequentially first mixing DNA with PC or CL, followed by addition of CL or PC, respectively, or simultaneously with both PC and CL. Particle size and zeta-potential were determined and gene transfer and cytotoxicity were quantified on COGA-3, -5, -12, HeLa and Sw480 cells.
  
  
  RESULTS
  The highest gene transfer was achieved when DNA was first complexed with PC followed by CL. At low ionic strength, particles were small (50-130 nm) with a zeta-potential of +20-40 mV. At physiological ionic strength, only lipoplexes of DOCSPER or DOSPER and their respective lipopolyplexes with PEI25br were stable to aggregation (140-220 nm). Lipopolyplexes of PEI25br were between 5- to 400-fold more efficient compared to the corresponding lipoplexes or polyplexes in all cases. Chloroquine did not significantly affect lipopolyplex-mediated gene transfer.
  
  
  CONCLUSIONS
  Lipopolyplex formulations of PEI25br in combination with multivalent CLs (DOCSPER, DOSPER) are promising tools for in vitro and potentially also in vivo gene transfer to colorectal cancer cells.
authors.affiliation: Department of Pharmacy, Center of Drug Research, Pharmaceutical Biology-Biotechnology, Ludwig Maximilian University, Munich, Germany. pelisek@gmx.de
authors.forename: Jaroslav
authors.initials: J
authors.lastname: Pelisek
authors.forename: Lars
authors.initials: L
authors.lastname: Gaedtke
authors.forename: Jason
authors.initials: J
authors.lastname: DeRouchey
authors.forename: Greg F
authors.initials: GF
authors.lastname: Walker
authors.forename: Sigrid
authors.initials: S
authors.lastname: Nikol
authors.forename: Ernst
authors.initials: E
authors.lastname: Wagner
mesh_terms: D002277:Carcinoma / Q000188:drug therapy / Q000378:metabolism*; D002738:Chloroquine / Q000494:pharmacology; D003110:Colonic Neoplasms / Q000188:drug therapy / Q000378:metabolism*; D003850:Deoxyribonuclease I; D018014:Gene Transfer Techniques; D005822:Genetic Vectors / Q000737:chemistry / Q000633:toxicity; D006367:HeLa Cells; D006801:Humans; D066298:In Vitro Techniques; D008055:Lipids / Q000737:chemistry / Q000633:toxicity; D018625:Microscopy, Atomic Force; D010957:Plasmids; D011073:Polyamines / Q000737:chemistry / Q000633:toxicity; D000071228:Polyelectrolytes
chemical_list: D002738:Chloroquine; D003850:Deoxyribonuclease I; D008055:Lipids; D011073:Polyamines; D000071228:Polyelectrolytes