Research of ultrasound vascular effects and drug delivery to tumor / 中华医学超声杂志（电子版）

ABSTRACT

Objective To improve the chemotherapy drug delivery to tumor by enhancing the tumor vascular perfusion induced by diagnostic ultrasound combined with microbubbles.Methods Ten healthy male sprague-dawley(SD)rats with total twenty walker-256 tumors implanted in the two back legs were randomized to the two paired groups controlled group(C,n=10)and treatment group(T,n=10).Tumors in the controlled group were ultrasonic sham operated,while in the treatment group were treated by diagnostic ultrasound combined with microbubbles.The treatment group were taken contrast-enhanced ultrasound(CEUS)before and after treatment and analyzed the quantitative parameters.The microbubbles used in the treatment and CEUS was a kind of self-made lipid microbubbles called Zhifuxian.The 0.02 ml microbubbles were bolus injected at CEUS,while during treatment,0.04 ml microbubbles diluted into 1 ml saline solution were injected slowly at constant speed.Flushed by saline solution after treatment,the rats' tumors were harvested into three parts one for chemotherapy drug concentration detected by high performance liquid chromatography(HPLC),one for HE detection,and one for Dox fluorescence intensity detected by confocal laser scanning microscopy(CLSM).The peak intensity(PI)values,the area under curve(AUC)values and the Dox concentration of each group were analyzed by pared-samples t test.Results(1)The contrast enhanced ultrasound quantitative analysis of the T group PI value of the tumors before and after treatment were 66.22±16.25 and 75.74±17.67.The AUC values were 2937.52±677.51 and 3354.91±796.15.There was significant statistical difference between them(t=-5.212,-5.259,all P ＜ 0.05).(2)The Dox concentration of the T and C groups were(1.15±0.25)ug/g and(0.96±0.21)ug/g.There was significant statistical difference between them(t=2.403,P＜0.05).The Dox concentration of the treatment group was 1.2 times of the controlled group.(3)The pathology results of T and C groups the tumor cells were arranged in cords,with big round deep-stained nucleus.No pathological changes were observed in the controlled group,and there was no significant difference between the two groups.But in the treatment group,tumor vascular congestion and inflammatory cell infiltration could be observed.(4)The confocal laser scanning microscopy(CLSM)detection of the T and C groups the Dox red fluorescence was distributed in the tumor tissue interstitial,and the fluorescence intensity and distribution area of the treatment group were significant higher than the controlled group.Conclusions Diagnostic ultrasound combined with microbubbles treatment could significantly increase the blood perfusion in the walker-256 tumors of SD rats.Taking advantage of this vascular effect,the chemotherapy drug Dox could be delivered much more to the tumor tissue along with circulating bloodstream.With the addition of the sonoporation effect induced by the cavitation of the microbubbles,the chemotherapy drugs could be released much more to the tumor interstitial tissue.