COUPLING OF CELL-BINDING LIGANDS TO POLYETHYLENIMINE FOR TARGETED GENE DELIVERY

Recently the high transfection potential of the cationic polymer polye thylenimine (PEI) was described (Boussif O et al. Proc Natl Acad Sci U SA 1995; 92: 7297-7301). To combine the promising DNA delivering activ ity of PEI with the concept of receptor-mediated gene delivery, cell-b inding ligands (transferrin or antiCD3 antibody) were incorporated by covalent linkage to PEI. DNA complexes of PEI or ligand-PEI conjugates were tested for transfection of cultured neuroblastoma Neuro 2A cells , melanoma B16 or H225 cells, erythroid leukemic K562 cells and T cell leukemia Jurkat E6.1 cells. Depending on the cell line, incorporation of the cell-binding ligand resulted in an up to 1000-fold increased t ransfection efficiency. This activity depends on ligand-receptor inter action and was observed also at low PEI cation.DNA anion ratios where ligand-free PEI lacks efficiency. Depending on the cell-binding ligand , specific targeting (CD3 antibody, Jurkat cells) can be achieved. Gen e transfer can be augmented by the addition of an endosome-destabilizi ng influenza peptide, but is not dependent on the presence of addition al endosomolytic agents. Application of transferrin-PEI for the produc tion of murine interleukin-2 in B16 cells resulted in exceptionally hi gh secretion rates of 19 mu g IL-2 protein per 10(6) cells per 24 h.