Enhancing suspended cell transfection by inducing localized distribution of the membrane actin cortex before exposure to electromechanical stimulation.

Objectives: During physical transfection, an electrical field or mechanical force is used to induce cell transfection. We tested if the disruption of a dense actin layer underneath the membrane of a suspended cell enhances cell transfection.

Results: A bubble generator was used to electromechanically stimulate suspended cells. To clarify the influence of the actin layer (the actin cortex) on cell transfection efficiency, we used an actin polymerization inhibitor (cytochalasin D) to disrupt the actin cortex before electromechanical stimulation. Without cytochalasin D treatment, signals from the overall actin cortex decreased after electromechanical stimulation. With cytochalasin D treatment, there was localized F-actin aggregation under static conditions. After electromechanical stimulation, there was a partial loss (localized disruption), but no overall disruption, of the actin cortex. With the pretreatment with cytochalasin D, the transfection efficiency of plasmids (4.7, 8.3, or 11 kbp) into NIH/3T3 or UMR-106 cells increased significantly after exposure to electromechanical stimulation.

Conclusions: Localized distribution of the actin cortex before exposure to electromechanical stimulation is crucial for inducing a partial loss of the cortex, which improves transfection efficiency and large plasmid delivery.