Diagnostic ultrasound and microbubbles therapy improves tumor perfusion and doxorubicin accumulation in a Rabbit VX2 tumor model

Hypoperfused tumors result in poor therapeutic outcomes, partly due to insufficient chemotherapeutic delivery. Herein, we aimed to enhance tumor perfusion and chemotherapeutic drug accumulation using diagnostic ultrasound and microbubbles and to explore the effect on reactive oxygen species. Thirty-three VX2-bearing New Zealand rabbits were randomly divided into 3 groups: doxorubicin with high pulse repetition frequency ultrasound (1000 Hz), low pulse repetition frequency ultrasound (500 Hz), and the control. Tumors were treated with a modified diagnostic ultrasound, microbubbles, and doxorubicin. Tumor perfusion, doxorubicin delivery, and reactive oxygen species were evaluated. The results showed that the tumor perfusion area was associated with the drug concentration (P<0.05). After ultrasound and microbubbles treatment, tumor perfusion was enhanced, and doxorubicin accumulation was increased (P<0.05), especially when the pulse repetition was 1000 Hz. Compared with the control, the drug concentration was 2.63-fold (1000 Hz) and 2.07-fold (500 Hz) by high-performance liquid chromatography, and 4.68-fold (1000 Hz) and 2.68-fold (500 Hz) by doxorubicin fluorescence. Reactive oxygen species significantly improved after treatment (P<0.05). In conclusion, diagnostic ultrasound and free microbubbles therapy could significantly improve tumor perfusion, subsequent doxorubicin accumulation, and reactive oxygen species. The presented treatment is a noninvasive, clinically translatable, and cost-effective method for the enhancement of therapeutic efficacy.