LIPID-MEDIATED ENHANCEMENT OF TRANSFECTION BY A NONVIRAL INTEGRIN-TARGETING VECTOR

Nonviral vectors consisting of integrin-targeting peptide/DNA (ID) com plexes have the potential for widespread application in gene therapy, The transfection efficiency of this vector, however, has been limited by endosomal degradation, We now report that lipofectin (L) incorporat ed into the ID complexes enhances integrin-mediated transfection, incr easing luciferase expression by more than 100-fold. The transfection e fficiency of Lipofectin/Integrin-binding peptide/DNA (LID) complexes, assessed by beta-galactosidase reporter gene expression and X-gal stai ning, was improved from 1% to 10% to over 50% for three different cell lines, and from 0% to approximately 25% in corneal endothelium in vit ro, Transfection complexes have been optimized with respect to their t ransfection efficiency and we have investigated their structure, funct ion, and mode of transfection, Both ID and LID complexes formed partic les, unlike the fibrous network formed by lipofectin/DNA complexes (LD ), Integrin-mediated transfection by LID complexes was demonstrated by the substantially lower transfection efficiency of LKD complexes in w hich the integrin-biding peptide was substituted for K-16 (K) Furtherm ore, the transfection efficiency of complexes was shown to be dependen t on the amount of integrin-targeting ligand in the complex, Finally, a 34% reduction in integrin-mediated transfection efficiency by LID co mplexes was achieved with a competing monoclonal antibody, The role of lipofectin in LID complexes appears, therefore, to be that of a co-fa ctor, enhancing the efficiency of integrin-mediated transfection, The mechanism of enhancement is likely to involve a reduction in the exten t of endosomal degradation of DNA.