Free- and liposomal- doxorubicin delivery via microbubble inertial cavitation

Intracellular delivery of anticancer drug, doxorubicin, by cell sonoporation is a fast-track technique for cancer treatment, however, the in vivo applications are limited by deleterious side-effects. In this assay, we have investigated sonotransfer efficiency of free and liposome loaded doxorubicin delivery into Chinese hamster ovary cells using Sonovue microbubbles. The sonotransfer course was simultaneously followed by cell confocal imaging and the registration of microbubble side and forward scattered signals. Obtained results indicate the assumption of spontaneous doxorubicin and microbubble interaction, implying the prerequisite for microbubble sonodestruction for efficient intracellular delivery. At the exposure conditions, associated to microbubble inertial cavitation, the evaluated therapeutic efficiency of liposome loaded doxorubicin was efficient (up to 40% reversible permeabilisation) and comparable to delivery rate of free doxorubicin. These results imply inertial cavitation to be efficient technique for doxorubicin extra-liposomal release and intracellular transfer. Cell death caused by doxorubicin activity was related to intranuclear as well as extranuclear mechanisms as revealed by cell confocal imaging. Quantified metric, the rate of forward scattering, has high (R > 0.9) and significant (p < 0.0001) correlation with doxorubicin sonotransfer efficiency and cell viability. This metric aims to optimize and allow the standardization of sonochemotherapy protocols.