Investigation of an Optical Imaging Platform Integrated with an Ultrasound Application System for In Vitro Verification of Ultrasound-Mediated Drug Delivery

Techniques that increase the permeability of the cell membrane and transfer drugs or genes to cells have been actively developed as effective therapeutic modalities. Also, in line with the development of these drug delivery techniques, the establishment of tools to verify the techniques at the cellular level is strongly required. In this study, we demonstrated an optical imaging platform integrated with an ultrasound application system to verify the feasibility of safe and efficient drug delivery through the cell membrane using ultrasound-microbubble cavitation. To examine the potential of the platform, fluorescence images of both Fura-2 AM and propidium iodide (PI) to measure calcium flux changes and intracellular PI delivery, respectively, during and after the ultrasound-microbubble cavitation in the cervical cancer cell were acquired. Using the optical imaging platform, we determined that calcium flux increased immediately after the ultrasound-microbubble cavitation and were restored to normal levels, and fluorescence signals from intracellular PI increased gradually after the cavitation. The results acquired by the platform indicated that ultrasound-microbubble cavitation can deliver PI into the cervical cancer cell without irreversible damage of the cell membrane. The application of an additional fluorescent imaging module and high-speed imaging modalities can provide further improvement of the performance of this platform. Also, as additional studies in ultrasound instrumentations to measure real-time cavitation signals progress, we believe that the ultrasound-microbubble cavitation-based sonoporation can be employed for safe and efficient drug and gene delivery to various cancer cells.