Evaluation of the Efficacy of Combined Treatment of Liver Cancer With Losartan and Ultrasound‑Stimulated Microbubble Cavitation

Objectives To investigate the combined therapeutic effects of “mechanotherapeutic” agent losartan and ultrasound-stimulated microbubble cavitation (USMC) on hepatocellular carcinoma (HCC). Methods C57BL/6 mice were assigned to five groups: losartan only, USMC only, combination (losartan+USMC), untreated HCC, and healthy controls. HCC was induced via intrahepatic implantation of Hepa1-6 cells at 6 weeks. Losartan was administered every other day. USMC was delivered five times (three sessions with low mechanical index (MI) followed by two sessions with high MI). Ultrasound resolution microscopy (URM) and ultrasound viscoelastic imaging (UVI) were performed before the first and after the last USMC treatment. URM quantified microvascular density, density ratio, blood-flow velocity, and perfusion index; UVI assessed elasticity, viscosity, and dispersion coefficients. Tumor volume, liver/body weight, and CD34 staining were analyzed at sacrifice. Results After USMC treatment, mean blood-flow velocity increased in combination group (9.7 ± 2.00 to 13.1 ± 1.59 mm/s, p = 0.006) and microvascular density, density ratio, and perfusion index reduced in USMC-treated groups. Viscoelasticity in three treated groups decreased after treatment and remained lower than untreated HCC but higher than healthy controls, with significant decline in the combination group (elasticity p = 0.006; viscosity p = 0.028; dispersion p < 0.001). Tumor volume was significantly reduced in all treated groups (p < 0.001). CD34 staining showed lower microvascular positivity in the USMC and combination groups. Conclusions Low- and high-MI USMC enhanced vascular permeability and induced vascular disruption, while losartan reduced stromal stiffness. Their combination produced additive therapeutic effects on HCC. URM and UVI provide complementary, noninvasive assessment of vascular and mechanical responses during mechanotherapeutic and cavitation-based treatments.