Journal of Neuro-Oncology

, Volume 26, Issue 1, pp 25–34 | Cite as

Internalization of microbubbles by tumor cellsin vivo andin vitro

  • Elisa Barbarese
  • Shih-Yieh Ho
  • Joseph S. D'Arrigo
  • Richard H. Simon
Laboratory Investigation


Lipid-coated microbubbles (LCM) administered intravenously (i.v.) to rats bearing brain tumor, specifically enhance tumor visualization by ultrasound [1]. In order to understand the basis for this observation, we have examined the interactions of LCM with glioblastoma (C6) and gliosarcoma (9L) tumor cellsin vivo andin vitro. LCM and LCM labeled with the fluorescent lipophilic dye 3,3′-dioctadecyloxacarbocyanine perchlorate (diO) were administered to rats bearing brain tumor. LCM and diO-labeled LCM were found principally at the tumor site with no evidence of label in the surrounding normal brain tissue. Analysis of the tumor by confocal laser scanning microscopy revealed that labeled LCM were inside the tumor cells. Similar analysis of LCM interactions with C6 and 9L cells in culture showed that LCM first adsorb at the surface of the cells, and with time became localized inside the cells. Binding and internalization proceeded faster at 37° C than at room temperature (RT). Staining of live cells with N-(3-((2,4-dinitrophenyl)amino)propyl)-N-(3-aminopropyl) methylamine dihydrochloride (DAMP), a dye that recognizes acidic compartments, showed that the majority of internalized LCM was associated with compartments containing DAMP. If the same uptake mechanism were operativein vivo, it would indicate that a portion of LCM bypasses the reticuloendothelial system and become endocytosed directly by tumor cells.

Key words

monolayer lipid droplets endocytosis lysosomes glioma 



N-(3-((2,4-dinitrophenyl)amino)propyl)-N-(3-aminopropyl)methylamine, dihydro-chloride


3,3′-dioctadecyloxacarbocyanine perchlorate






lipid-coated microbubbles


room temperature


Texas red


wheat germ agglutinin


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Copyright information

© Kluwer Academic Publishers 1995

Authors and Affiliations

  • Elisa Barbarese
    • 1
  • Shih-Yieh Ho
    • 2
  • Joseph S. D'Arrigo
    • 3
  • Richard H. Simon
    • 2
  1. 1.Dept. of Neurology, Surgical Research Ctr.University of Connecticut Health CenterUSA
  2. 2.Dept. of Surgery, Div. of NeurosurgeryUniversity of Connecticut Health CenterUSA
  3. 3.CAV-CON Inc.FarmingtonUSA

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