Quantitative Evaluation of Ultrasound-Mediated Cellular Uptake of a Fluorescent Model Drug

Purpose This study aims to quantitatively analyze cellular uptake following local ultrasound (US)-mediated cell permeabilization. Procedures A 2 μM cell-impermeable dye Sytox Green was co-injected with 3 × 10 7 microbubbles in the presence of C6 rat glioblastoma cell monolayer in total volume of 10 ml. A 5.8-mm diameter mono-element US transducer was positioned at a distance of 8 mm to the Opticell® membrane. Acoustical pressure of pulsed US was varied from 0.62 MPa peak-to-peak (p-p) to 1.25 MPa p-p. Large field of view (FOV = 15 × 15 mm) 22 × 22 mosaic acquisitions were done under epifluorescence Leica DMR microscope and analyzed in Metamorph software to evaluate cell density as well as model drug uptake percentage. Results The size of acoustical field of the transducer closely matches the spatial pattern of the model drug internalized into the cells by US. Maximum of uptake percentage (42 ± 15 %) was found at 0.88 MPa p-p. Conclusions Spatial aspect of US-mediated model drug uptake has been quantitatively evaluated on adherent cells using robust 2D-mapping approach.