Effect of contrast-enhanced ultrosound imaging with CCR2 targeted microbubbles on murine breast tumor model / 中华超声影像学杂志

ABSTRACT

Objective To develop and validate a ultrasonographic (US)imaging agent with targeted microbubbles that attaches to chemokine receptor 2 (CCR2)and to compare the US single obtained from targeted microbubble with that from control microbubble in murine breast tumor model.Methods The microbubble which carried CCR2 antibody (MBCCR2 )and isotype-macthed immunoglobulin G-labled control microbubble (MBcontrol ) were prepared. The microbubble size and distribution were assessed by AccuSizer780.Binding specificities of targeted microbubble compared with control microbubble were tested with murine microvascular endothelial cells (bEnd.3 ).Orthotopic breast tumor model was estabished in BALB/c mice with mouse breast cancer 4T1 cell.In vivo imaging signals of contrast material-enhanced ultrasound by use these two different types of microbubble which were injected respectively into each mouse at random order and 30 min interval.Tumor tissue was stained for CCR2 and CD3 1 .Results Automatic Particle Sizer showed size uniform of two kinds of microbubbles,and narrow distribution of particle size (mean diameter of about 1 -2 μm),which were not significantly different (P >0.05).Adhension to bEnd. 3 endothelial cells was significantly higher (P < 0.001 )for MBCCR2 (mean,9.50 ± 1 .5 1 )than that for MBcontrol (mean,0.01 ±0.01).Imaging signal in the murine tumor model was significantly higher for MBCCR2 [mean,(6.76±0.26)dB]than that for MBcontrol [mean,(1 .06 ±0.62)dB,P <0.001 ].Immunofluorescence confirmed expression of CCR2 on tumor vasculature.Conclusions The targeted microbubbles with CCR2 monoclonal antibody had been successfully prepared,which precisely targeted to CCR2 of tumor angiogenesis in the murine breast cancer xenograft tumor models in vivo.These results suggest that the targeted microbubbles as a kind of ultrasound molecular imaging agent with a better specificity can be used for both evaluating tumor neovascularization and monitoring therapeutic effect of anti-angiogenesis.