A novel strategy of selective gene delivery by using a uniform magnetic field

The application of a magnetic field to enhance the transfection efficiency has been reported to be mainly dependent on the magnetic force generated by a magnetic field gradient to attract paramagnetic bead‐conjugated carrier and polynucleotide complexes. This strategy has the advantage of targeting a point or an area on the culture vessel. However, it is difficult to target deeply placed tissues in vivo. Uniform magnetic field‐correlated effect is applicable to such a purpose. Here, we attempted to establish a novel procedure for uniform magnetic field‐dependent enhancement of transfection efficiency. We examined the effect of a 1.5 mT uniform magnetic field on cellular reactive oxygen species (ROS) level and transfection efficiency mediated by a ROS‐sensitive transfection carrier. Our experimental results revealed that a 1.5 mT uniform magnetic field transiently decreased cellular ROS levels and strongly enhanced transfection efficiency mediated by polyethylenimine (PEI). The uniform magnetic field‐dependent enhancement of PEI‐mediated in vivo transfection was confirmed in the livers of mice. Local intensification of a uniform magnetic field in a culture dish resulted in selective gene delivery into cells on the target area. Although further examination and improvement are necessary for this procedure, our findings provide a novel option for spatial control of gene delivery. The authors demonstrate that a 1.5 mT uniform magnetic field transiently decreases cellular reactive oxygen species (ROS) level and strongly enhances transfection efficiency mediated by polyethylenimine (PEI), a ROS‐sensitive transfection carrier. This novel enhancing approach of transfection efficiency is applicable to selective gene delivery by using a locally intensified uniform magnetic field.