Pegylated Polyethylenimine−Fab‘ Antibody Fragment Conjugates for Targeted Gene Delivery to Human Ovarian Carcinoma Cells

Specific targeting of ovarian carcinoma cells using pegylated polyethylenimine (PEG−PEI) conjugated to the antigen binding fragment (Fab‘) of the OV-TL16 antibody, which is directed to the OA3 surface antigen, was the objective of this study. OA3 is expressed by a majority of human ovarian carcinoma cell lines. To demonstrate the ability of the PEG−PEI−Fab‘ to efficiently complex DNA, an ethidium bromide exclusion assay was performed. Comparison with PEG−PEI or PEI 25 kDa showed only minor differences in the ability to condense DNA. Since conjugation of Fab‘ to PEG−PEI might influence complex stability, this issue was addressed by incubating the complexes with increasing amounts of heparin. This assay revealed stability similar to that of unmodified PEG−PEI/DNA or PEI 25 kDa/DNA complexes. Complexes displayed a size of approximately 150 nm with a zeta potential close to neutral. The latter property is of particular interest for potential in vivo use, since a neutral surface charge reduces nonspecific inte...