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Objective:To explore the capability of vascular endothelial growth factor receptor 2 (VEGFR2)/integrinα vβ 3 dual-targeted microbubbles in assessing the expression level of pro-angiogenic factors during renal cell carcinoma (RCC) growth. Methods:VEGFR2/integrinα vβ 3 dual-targeted microbubbles were prepared by using biotin-avidin linkage method. Twenty subcutaneous RCC xenografts in nude mice were established by subcutaneously injecting 786-O cells and then divided into 2 groups randomly. The targeted contrast-enhanced ultrasound (t-CEUS) examination was performed for all 10 mice in the first group when xenograft tumors were metered from 5 to 10 mm and >10 to 20 mm respectively. And the quantitative parameters of RCC on t-CEUS were longitudinally evaluated during tumor growth. The second group were divided into two subgroups according to xenograft tumors′ diameter, which was 5 to 10 mm and >10 to 20 mm respectively, and underwent t-CEUS examination. Quantitative analysis was performed for all t-CEUS images to obtain the targeted quantitative parameters, which including peak intensity (PI), area under the time-intensity curve (AUC), the differential tissue enhancement (dTE, presenting the difference in PI before (P 1) and after (P 2) the process of Flash). All xenograft tumors in the second group were harvested for immunohistochemical staining to observe the expression of VEGFR2, integrinα vβ 3 and CD31, and their differences in RCC with different tumor sizes. And the correlations between quantitative parameters and VEGFR2, integrinα vβ 3 and CD31 were analyzed. Results:The longitudinal comparison showed that there were statistically significant differences between AUC and dTE of RCC with different tumor sizes (all P<0.001). The larger the tumor size, the smaller the parameters were. According to the horizontal comparison, the expression levels of VEGFR2 and integrinα vβ 3 in larger RCCs were higher than those of RCCs with smaller size (both P<0.05), but there was no significant difference in CD31 expression between the two subgroups ( P=0.754). Both the targeted quantitative parameters (AUC anddTE ) and pro-angiogenic factors (VEGFR2 and integrinα vβ 3) were negatively correlated with tumor size ( rs=-0.83, -0.81, -0.70, -0.88; all P<0.05). Further more, there were good positive correlations between AUC and VEGFR2, integrinαvβ ( rs=0.76, 0.72; all P<0.05). There were good positive correlations between dTE and VEGFR2, integrinα vβ 3 ( rs=0.81, 0.70; all P<0.05). Additionally, the parameter PI was positively correlated with the expression of CD31 ( rs=0.70, P=0.025). Conclusions:The t-CEUS, mediated by VEGFR/integrinα vβ 3 dual-targeted microbubbles, allows noninvasive assessment of the expression levels of VEGFR2 and integrinα vβ 3 in RCCs, which decrease gradually with the increase of tumor size.
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Hepatic fibrosis develops as a wound-healing scar in response to acute and chronic liver inflammation and can lead to cirrhosis in patients with chronic hepatitis B and C. The condition arises due to increased synthesis and reduced degradation of extracellular matrix (ECM) and is a common pathological sequela of chronic liver disease. Excessive deposition of ECM in the liver causes liver dysfunction, ascites, and eventually upper gastrointestinal bleeding as well as a series of complications. However, fibrosis can be reversed before developing into cirrhosis and has thus been the subject of extensive researches particularly at the gene level. Currently, therapeutic genes are imported into the damaged liver to delay or prevent the development of liver fibrosis by regulating the expression of exogenous genes. One technique of gene delivery uses ultrasound targeting of microbubbles combined with therapeutic genes where the time and intensity of the ultrasound can control the release process. Ultrasound irradiation of microbubbles in the vicinity of cells changes the permeability of the cell membrane by its cavitation effect and enhances gene transfection. In this paper, recent progress in the field is reviewed with emphasis on the following aspects: the types of ultrasound microbubbles, the construction of an ultrasound-mediated gene delivery system, the mechanism of ultrasound microbubble-mediated gene transfer and the application of ultrasound microbubbles in the treatment of liver fibrosis.
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Objective To explore the express of von willebrand factor(vWF) and tissue factor(TF) in ultrasound combined with urokinase and RGDS-targeted microbubbles for recanalization of occluded rabbit femoral artery.Methods A total of 42 rabbits with platelet-rich thrombi in the femoral artery were randomized into 7 treatment groups (n =6 in each group):①ultrasound alone (US) group;②ultrasound,non-targeted microbubbles (US + M) group;③urokinase alone (UK) group;④ ultrasound,non-targeted microbubble and urokinase (US + M + UK) group;⑤ ultrasound,platelet-targeted microbubble (US + R) group;⑥ platelet-targeted microbubble,urokinase (R + UK) group;⑦ ultrasound,platelet-targeted microbubble and urokinase (US + R + UK) group.A total of 6 ml of infusion liquor of urokinase,RGDS and microbubbles (SonoVue) were mixed by the direct conjugation method,infusion via vein within 20 min.Ultrasound was conducted to lyse the clot for 30 min.The recanalization and the velocity tracing change of blood flow in thrombolytic process and the express of vWF and TF were evaluated at 120 min post treatment.Results For US,UK,US + M,US + R and US + M + UK groups,recanalization were failed.The R + UK and US + R + UK groups were partly recanalizated or completed recanalized (P ＜0.001).vWF and TF were positive in US,US + M,US + R and R + UK group.vWF and TF were negative in US + M + UK,UK and US + R + UK groups.Conclusions The combined effects of low frequency ultrasound and targeted microbubble combined with urokinase can inhibit the expression of vWF and TF,and then promote the thrombolysis,however it can affect the expression of vWF and TF after reperfusion.