Targeted gene transfer to human hematopoietic progenitor cell lines through the c-kit receptor

In this report, we describe a novel gene therapy approach for hematopoietic stem/progenitor cells using a specific receptor-mediated gene transfection procedure to target c-kit+ cell lines. The vector consists of plasmid DNA containing a luciferase reporter gene that is condensed by electrostatic forces with polylysine (PL) covalently linked to streptavidin (binds biotinylated ligand) and PL covalently linked to adenovirus (AD; to achieve endosomal lysis) with the final addition of biotinylated steel factor (SLF-biotin). Targeted transfection of growth factor-dependent hematopoietic progenitor cell lines that express c-kit showed specific luciferase gene expression over cell lines that did not express c-kit. This effect was dependent on the dose of SLF-biotin and was competed by excess SLF or with monoclonal antibodies that recognize c-kit and block the binding of SLF to its receptor. Maximum transfection efficiency (> 90%) requires a 2-hour incubation period of the vector with the cells, and maximum gene expression occurred 30 hours later. Removal of the endosomalytic agent, AD, from the vector resulted in the loss of gene expression. Vector targeting was versatile and could be changed by the addition of other biotinylated ligands. In principle, this vector should be broadly applicable to deliver genes to hematopoietic stem/progenitor cells in vitro and in vivo.