Bifidobacterium combined with cationic lipid nanoparticles with liquid perflurocarbon for improving HIFU ablation effect: Experimental study / 中国介入影像与治疗学

ABSTRACT

Objective: To investigate the influence of bifidobacterium combined with cationic lipid nanoparticles with liquid fluorocarbon on HIFU ablation for tumor-bearing mice. Methods: Bifidobacterium was cultured, cationic lipid nanoparticles with liquid fluorocarbon were prepared, and the connection ratio was examined in vitro. Mice models of human breast cancer MDA-MB231 cells were established. A total of 48 tumor-bearing mice were randomly divided into 4 groups (each n=12). Different substances were injected through the tail vein twice (two days apart). Tumor-bearing mice in group A (PBS group) were injected with phosphate buffer (PBS) twice, in group B (bifidobacterium group) were injected with bifidobacterium before PBS injection, in group C (cationic lipid nanoparticles) with PBS before cationic lipid nanoparticles injection and in group D (bifidobacterium+cationic lipid nanoparticle group) with bifidobacterium before cationic lipid nanoparticles injection. Twenty-four hours after the completion of the second injection, HIFU irradiation was performed on the tumor tissue of tumor-bearing mice, and the changes between pre- and post-ablation gray scale of the tumor tissue were analyzed. Histological examination was performed 1 h before HIFU irradiation and 1 day after irradiation, respectively. The tumor targeting of bifidobacterium was observed, and the coagulative necrotic volume of tumor tissues and energy efficiency factor (EEF) of HIFU ablation were measured. Statistical analysis was performed to compare the differences among 4 groups. Results: Gram-stained bifidobacterium longum was manifested as blue-violet long rod with a surface potential of -29 mV. The cationic lipid nanoparticles were spherical and evenly distributed with average particle diameter of (280.21±60.20)nm and a surface potential of 25 mV. The differences of gray scale change (F=143.40), coagulative necrotic volume (F=243.20) and EEF (F=56.33) were statistically significant among 4 groups (all P<0.001). Gray value change and coagulative necrotic volume gradually increased in group A, B, C and D (pairwise comparison: All P<0.05), while EEF trended from high to low in group A, B, C and D (pairwise comparison: All P<0.05). There was no bifidobacterium in heart, liver, spleen, lung and kidney of tumor-bearing mice among 4 groups nor in tumors of group A and C. A quantity of bifidobacterium was found in tumor tissue of group B and D. Conclusion: Bifidobacteriaum combined with cationic lipid nanoparticles with liquid fluorocarbon can enhance the ablation effect of HIFU ablation on tumor tissue in tumor-bearing mice.