title: Transfection by polyethyleneimine-coated microspheres.
abstract: Polyethyleneimine (PEI) can be used as a DNA delivery mechanism in cell culture and in vivo. Cells can be transfected by using surface-bound PEI, as well as by PEI/DNA microparticles. In the present experiments we extended these observations by preparing microspheres with covalently attached PEI. Blends of poly(epsilon-CBZ-L-lysine) mixed with poly(D,L-lactic-co-glycolic acid) were formed into microspheres using a double-emulsification/solvent evaporation procedure. CBZ (carbobenzoxy) groups on the surface of microspheres were removed by Li(0) /liquid ammonia reduction. Surface amino groups were used for covalent attachment of PEI and other molecules. Silica microspheres with bonded-phase PEI were also used. Microspheres were mixed with plasmid DNA encoding green fluorescent protein and added to cultured cells. PEI-coated microspheres transfected cultured Caco cells and MH-S alveolar macrophages. Expression of the transfected DNA increased over several days. MH-S cells phagocytosed PEI-coated silica microspheres, which were shown to reside in an acidic subcellular compartment. This was demonstrated by conjugating a pH-sensitive fluorescent dye (seminaphthofluorescein, SNAFL) to the microsphere surface. Transfection of MH-S cells was increased when plasmid DNA was complexed with histone on the surface of the microspheres.
  
  
  CONCLUSIONS
  PEI-coated microspheres have potential as a DNA delivery device with advantages of the unique properties of PEI and ease of surface chemical modification.
authors.affiliation: Huffington Center on Aging and Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, U.S.A.
authors.forename: W S
authors.initials: WS
authors.lastname: Manuel
authors.forename: J I
authors.initials: JI
authors.lastname: Zheng
authors.forename: P J
authors.initials: PJ
authors.lastname: Hornsby
mesh_terms: D016475:3T3 Cells; D000818:Animals; D002460:Cell Line; D020099:Coated Materials, Biocompatible; D046508:Culture Techniques; D015870:Gene Expression; D049452:Green Fluorescent Proteins; D006801:Humans; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008239:Lysine / Q000031:analogs & derivatives / Q000737:chemistry; D016676:Macrophages, Alveolar / Q000378:metabolism; D051379:Mice; D008863:Microspheres; D010957:Plasmids; D011094:Polyethyleneimine; D014162:Transfection / Q000379:methods*; D014407:Tumor Cells, Cultured / Q000378:metabolism
chemical_list: D020099:Coated Materials, Biocompatible; D008164:Luminescent Proteins; D049452:Green Fluorescent Proteins; D011094:Polyethyleneimine; D008239:Lysine