title: RGD-Targeted Ultrasound Contrast Agent for Longitudinal Assessment of Hep-2 Tumor Angiogenesis In Vivo.
abstract: OBJECTIVE
  To prepare arginine-glycine-aspartate (RGD)-targeted ultrasound contrast microbubbles (MBs) and explore the feasibility of their use in assessing dynamic changes in αvβ3 integrin expression in a murine model of tumor angiogenesis.
  
  
  METHODS
  RGD peptides were conjugated to the surfaces of microbubbles via biotin-avidin linkage. Microbubbles bearing RADfK peptides were prepared as controls. The RGD-MBs were characterized using an Accusizer 780 and optical microscopy. The binding specificity of the RGD-MBs for ανβ3-expressing endothelial cells (bEnd.3) was demonstrated in vitro by a competitive inhibition experiment. In an in vivo study, mice bearing tumors of three different stages were intravenously injected with RGD-MBs and subjected to targeted, contrast-enhanced, high-frequency ultrasound. Subsequently, tumors were harvested and sectioned for immunofluorescence analysis of ανβ3 expression.
  
  
  RESULTS
  The mean size of the RGD-MBs was 2.36 ± 1.7 μm. The RGD-MBs showed significantly higher adhesion levels to bEnd.3 cells compared to control MBs (P < 0.01). There was rarely binding of RGD-MBs to αvβ3-negative MCF-7 cells. Adhesion of the RGD-MBs to the bEnd.3 cells was significantly inhibited following treatment with anti-alpha(v) antibodies. The quantitative acoustic video intensity for high-frequency, contrast-enhanced ultrasound imaging of subcutaneous human laryngeal carcinoma (Hep-2) tumor xenografts was significantly higher in small tumors (19.89 ± 2.49) than in medium tumors (11.25 ± 2.23) and large tumors (3.38 ± 0.67) (P < 0.01).
  
  
  CONCLUSIONS
  RGD-MBs enable noninvasive in vivo visualization of changes in tumor angiogenesis during tumor growth in subcutaneous cancer xenografts.
authors: Department of Diagnostic Ultrasound, the People's Hospital of Guangxi Zhuang Autonomous Region, Nanning, China.
authors: Qiao
authors: Q
authors: Hu
authors: Department of Diagnostic Ultrasound, the People's Hospital of Guangxi Zhuang Autonomous Region, Nanning, China.
authors: Xiao-Yan
authors: XY
authors: Wang
authors: Department of Diagnostic Ultrasound, the People's Hospital of Guangxi Zhuang Autonomous Region, Nanning, China.
authors: Li-Ke
authors: LK
authors: Kang
authors: Department of Pathology, the People's Hospital of Guangxi Zhuang Autonomous Region, Nanning, China.
authors: Hai-Ming
authors: HM
authors: Wei
authors: Department of Diagnostic Ultrasound, the People's Hospital of Guangxi Zhuang Autonomous Region, Nanning, China.
authors: Chun-Mei
authors: CM
authors: Xu
authors: Department of Otolaryngology-Head & Neck Surgery, the People's Hospital of Guangxi Zhuang Autonomous Region, Nanning, China.
authors: Tao
authors: T
authors: Wang
authors: Department of Pathology, the People's Hospital of Guangxi Zhuang Autonomous Region, Nanning, China.
authors: Zong-Hua
authors: ZH
authors: Wen
mesh_terms: D000162:Acoustics; D000818:Animals; D001360:Avidin / Q000737:chemistry; D001667:Binding, Competitive; D001710:Biotin / Q000737:chemistry; D002448:Cell Adhesion; D002460:Cell Line; D045744:Cell Line, Tumor; D003287:Contrast Media / Q000737:chemistry*; D004195:Disease Models, Animal; D042783:Endothelial Cells / Q000166:cytology; D005260:Female; D006801:Humans; D039302:Integrin alphaVbeta3 / Q000378:metabolism*; D061986:MCF-7 Cells; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D045423:Microbubbles; D008856:Microscopy, Fluorescence; D009368:Neoplasm Transplantation; D009389:Neovascularization, Pathologic / Q000000981:diagnostic imaging*; D009842:Oligopeptides / Q000737:chemistry*; D010455:Peptides / Q000737:chemistry; D011485:Protein Binding; D014463:Ultrasonography / Q000379:methods; D014741:Video Recording
chemical_list: D003287:Contrast Media; D039302:Integrin alphaVbeta3; D009842:Oligopeptides; D010455:Peptides; D001360:Avidin; D001710:Biotin; C047981:arginyl-glycyl-aspartic acid