Impact of Convective Flow on the Cellular Uptake and Transfection Activity of Lipoplex and Adenovirus

An in vitro cell culture model that mimics in vivo extracellular environment would be useful in developing in vivo gene delivery system. In the present study, a parallel flow model was applied to investigate the impact of convective flow on cellular uptake and transfection activity in endothelial cells. LipofectAMINE PLUS and adenovirus were used as model vectors, which bind cells via electrostatic- and ligand-receptor interactions, respectively. Whereas a convective flow increased the total amount of vector passing through the flow chamber by 3 orders of magnitude, uptake was increased by less than 10-fold, suggesting that the flow severely inhibited cellular uptake by reducing the retention time in the chamber and/or by diminishing the affinity between the cell and vector. Moreover, the uptake of both vectors was increased in a shear stress-dependent manner to a comparable extent, suggesting that the effect of flow on the cellular uptake was not significant. In contrast, transfection efficiency (TE), expressed as the transfection activity normalized by the cellular uptake of vectors was dramatically stimulated by shear stress, only when LipofectAMINE PLUS was used. Since the activities of the CMV promoter were unaffected by a shear stress, it is possible that altered intracellular trafficking may responsible for the improvement in lipoplex-mediated TE, presumably related to the cellular uptake pathway.