Vibrating microbubbles poking individual cells: Drug transfer into cells via sonoporation

Ultrasound contrast microbubbles have the ability to enhance endothelial cell permeability and thus may be used as a new way to deliver drugs. It facilitates the transfer of extracellular molecules into cells activated through ultrasound driven microbubbles. The present study is designed to correlate the relationship between microbubble induced cell deformation and enhanced cell membrane permeability. Propidium iodide (PI) was used as a membrane integrity probe. Using high-speed imaging of vibrating microbubbles against endothelial cells and imaging transport of PI into these cells showed a direct correlation between cell deformation and resulting cell membrane permeability. The membrane permeabilization lasted for a short period without affecting endothelial cells viability. We identified that microbubbles are crucial to enhance transient cell membrane permeability. Thus, permeability of individual cells is increased. The roles of ultrasound contrast microbubbles as the trigger for improved drug efficacy are discussed. (c) 2006 Elsevier B.V. All rights reserved.