Ellegala Dilantha B, Leong-Poi Howard, Carpenter Joan E, Klibanov Alexander L, Kaul Sanjiv, Shaffrey Mark E, Sklenar Jiri, Lindner Jonathan R
Department of Neurosurgery, University of Virginia School of Medicine, Charlottesville, USA.
Circulation. 2003 Jul 22;108(3):336-41. doi: 10.1161/01.CIR.0000080326.15367.0C. Epub 2003 Jun 30.
Angiogenesis is a critical determinant of tumor growth and metastasis. We hypothesized that contrast-enhanced ultrasound (CEU) with microbubbles targeted to alpha(v)-integrins expressed on the neovascular endothelium could be used to image angiogenesis.
Malignant gliomas were produced in 14 athymic rats by intracerebral implantation of U87MG human glioma cells. On day 14 or day 28 after implantation, CEU was performed with microbubbles targeted to alpha(v)beta3 by surface conjugation of echistatin. CEU perfusion imaging with nontargeted microbubbles was used to derive tumor microvascular blood volume and blood velocity. Vascular alpha(v)-integrin expression was assessed by immunohistochemistry, and microbubble adhesion was characterized by confocal microscopy. Mean tumor size increased markedly from 14 to 28 days (2+/-1 versus 35+/-14 mm2, P<0.001). Tumor blood volume increased by approximately 35% from day 14 to day 28, whereas microvascular blood velocity decreased, especially at the central portions of the tumors. On confocal microscopy, alpha(v)beta3-targeted but not control microbubbles were retained preferentially within the tumor microcirculation. CEU signal from alpha(v)beta3-targeted microbubbles in tumors increased significantly from 14 to 28 days (1.7+/-0.4 versus 3.3+/-1.0 relative units, P<0.05). CEU signal from alpha(v)beta3-targeted microbubbles was greatest at the periphery of tumors, where alpha(v)-integrin expression was most prominent, and correlated well with tumor microvascular blood volume (r=0.86).
CEU with microbubbles targeted to alpha(v)beta3 can noninvasively detect early tumor angiogenesis. This technique, when coupled with changes in blood volume and velocity, may provide insights into the biology of tumor angiogenesis and be used for diagnostic applications.
血管生成是肿瘤生长和转移的关键决定因素。我们推测，使用靶向新生血管内皮细胞上表达的α(v)整合素的微泡的超声造影（CEU）可用于对血管生成进行成像。
通过脑内植入U87MG人胶质瘤细胞在14只无胸腺大鼠中产生恶性胶质瘤。在植入后第14天或第28天，使用通过echistatin表面偶联靶向α(v)β3的微泡进行CEU。使用非靶向微泡的CEU灌注成像来得出肿瘤微血管血容量和血流速度。通过免疫组织化学评估血管α(v)整合素表达，并通过共聚焦显微镜表征微泡粘附。平均肿瘤大小从14天到28天显著增加（2±1对35±14mm2，P<0.001）。肿瘤血容量从第14天到第28天增加了约35%，而微血管血流速度下降，尤其是在肿瘤的中央部分。在共聚焦显微镜下，靶向α(v)β3的微泡而非对照微泡优先保留在肿瘤微循环内。肿瘤中靶向α(v)β3的微泡的CEU信号从14天到28天显著增加（1.7±0.4对3.3±1.0相对单位，P<0.05）。靶向α(v)β3的微泡的CEU信号在肿瘤周边最大，此处α(v)整合素表达最突出，并且与肿瘤微血管血容量密切相关（r=0.86）。
使用靶向α(v)β3的微泡的CEU可以无创地检测早期肿瘤血管生成。该技术与血容量和血流速度的变化相结合，可能有助于深入了解肿瘤血管生成的生物学特性，并用于诊断应用。
