Targeted transfection of the IL-3 gene into primary human hematopoietic progenitor cells through the c-kit receptor.

We recently showed that an antibody-mediated gene transfer procedure termed antifection can be used for targeted gene delivery into lymphoid cells in vitro and in vivo. We here report that antifection also is effective for targeted gene transfer to immature hematopoietic cells. A human IL3-expressing plasmid was chemically linked to an anti-human CD117 antibody. Delivery of the IL3 plasmid into IL-3-dependent myeloid TF-1 cells (bearing the CD117 antigen) was specific and resulted in the transient proliferation of the targeted cells in the absence of exogenous IL-3. Transfection of primary human CD34+ hematopoietic stem/progenitor cells led to transient production of IL-3 and transient proliferation of the target cells. Interestingly, by using a semisolid progenitor cell assay, we found that transfected primary CD34+ cells were able to generate normal numbers of cell colonies in the absence of exogenous IL-3. Polymerase chain reaction analysis confirmed the presence and expression of the IL-3 transgene in the progenitor-derived colonies. In conclusion, our data show that CD117 is a suitable cell surface target to specifically transfer gene by antifection into primary CD34+ cells and that delivery of IL-3 gene in these cells resulted in the expression of a functional IL-3 able to support cell growth in absence of exogenous cytokine. Thus, antifection may provide new therapeutic modality relying on the transient production of appropriate growth factors acting via autocrine and/or paracrine mechanisms.