Transgene expression, but not gene delivery, is improved by adhesion-assisted lipofection of hematopoietic cells

In contrast to adherent cells, cells growing in suspension and particularly hematopoietic cells, are notoriously difficult to transfect in vitro using nonviral approaches. In the present study, the effect of cell adhesion on gene transfer efficacy was investigated by allowing hematopoietic cells to bind to an adherent cell monolayer (ACM) before being subjected to cationic liposome-mediated DNA transfer. Human CD34 and T CD4 cell lines were culti vated on an ACM constituted of murine fibroblast NIH3T3 cells and transfect ed with a plasmid carrying the beta-galactosidase gene. X-gal staining show ed that up to 27% of the cells expressed the transgene. In contrast, less t han 0.1% of these cells were positively transfected in suspension. This adh esion-assisted lipofection (AAL) procedure was also successfully tested on blood lymphocytes, since it resulted in up to 30% of transfected human prim ary T lymphocytes. Flow cytometry analysis performed on T lymphocyte subset s revealed that 8 and 9%, respectively, of CD4 and CD8 cells could be trans fected with a plasmid carrying the green fluorescent protein gene. Other ad herent cells, such as MS5 murine stromal cells or HeLa epithelial cells, we re; also a compatible matrix for AAL. Moreover, the pCMV beta plasmid was p resent in similar amounts in the nuclei of TF1 cells transfected in suspens ion or with the AAL procedure. These data raise the possibility that cell m atrix/hematopoietic cell interactions might govern expression of the transg ene in hematopoietic cells growing usually in suspension, but not endocytos is of liposome/DNA particles and plasmid migration to the cell nucleus.