Targeted oligonucleotide delivery in human lymphoma cell lines using a polyethyleneimine based immunopolyplex.

The efficacy of antisense gene therapy depends on efficient delivery of oligonucleotides into targeted cells. Although polyethyleneimine based polyplexes have been reported as good transfection reagents, they are inefficient in lymphoid cell transfection. We report the construction of an immunopolyplex, a targeted nonviral vector based on a polyplex backbone and its application for oligonucleotide transfer on human lymphoma cell lines. The salient characteristic of immunopolyplex lies in the possibility of easily replacing the targeting element (antibody), leaving the polyplex backbone intact. Furthermore, a study was made of the influence of endocytosis inhibitors on immunopolyplex activity. The capacity of the immunopolyplex for oligonucleotide transfer was studied in vitro using FITC-labeled oligonucleotides as fluorescent reporters, an anti-CD3 antibody as targeting element, and a CD3-positive cell line (Jurkat) as a target cell line, in the absence and presence of endocytosis inhibitors. A CD3-negative Jurkat-derived mutant cell line (J.RT3-T3.5) was used as control. A nine-fold increase in fluorescence in the CD3-positive above that in the CD3-negative cell line was observed, indicating that oligonucleotide transfer is mainly specific. Low fluorescence values were obtained in the presence of endocytosis inhibitor or with untargeted polyplexes. We conclude that the immunopolyplex is a good nonviral vector for specific oligonucleotide delivery. Abolition of immunopolyplex activity in the presence of endocytosis inhibitor suggests that targeted oligonucleotide transfer occurs through an endocytic pathway.