Endothelial dysfunction is characterized by the upregulation of leukocyte adhesion molecules, including intercellular adhesion molecule-1 (ICAM-1), and has been identified in numerous disease processes including inflammation, atherosclerosis, transplant rejection, and neoplasia, yet current clinical techniques to assess endothelial dysfunction are limited. An ultrasound-based molecular imaging technique to detect cell surface markers of endothelial dysfunction may offer non-invasive assessment of associated disease processes.
Lipid-based ultrasound contrast microbubbles were targeted to ICAM-1 by conjugation with anti-ICAM-1 antibodies. These targeted microbubbles should selectively adhere to dysfunctional endothelium overexpressing ICAM-1, producing stronger and more persistent contrast enhancement during ultrasound imaging. Previous results from our laboratory demonstrated that ICAM-1-targeted microbubbles preferentially adhere to inflammatory versus normal endothelium in vitro under static conditions.
In the current studies, we first verified that ICAM-1 was upregulated in a variety of inflammatory models using immunohistochemistry. Next, various parameters that modulate adhesion of targeted microbubbles to dysfunctional endothelium were investigated. We quantified and demonstrated control over the final antibody density on the microbubble. Using a parallel plate perfusion chamber and a radial flow chamber, ICAM-1-targeted microbubble adhesion to cultured human endothelium was shown to be greater to inflammatory than non-inflammatory cells, and linearly dependent on microbubble antibody density, wall shear rate, and endothelial ICAM-1 density.
In vivo experiments using a rat heart transplant model demonstrated that ultrasound imaging using ICAM-1-targeted microbubbles can non-invasively detect acute cardiac allograft rejection. Using a mouse subcutaneous tumor model, we demonstrated that ultrasound imaging using microbubbles targeted via a tumor endothelium-specific binding peptide can non-invasively identify tumor vasculature.
These data have implications for the development of targeted contrast agents capable of identifying endothelial molecular markers of disease, and offer promise for the optimization and clinical application of a targeted, contrast-enhanced ultrasound imaging technique for the diagnosis and monitoring of disease states associated with endothelial dysfunction.
| Identifer | oai:union.ndltd.org:PITT/oai:PITTETD:etd-04062003-174803 |
| Date | 08 May 2003 |
| Creators | Weller, Gregory Eugene Robert |
| Contributors | Flordeliza S. Villanueva, William R. Wagner, Michael K. K. Wong, Harvey S. Borovetz, William J. Federspiel |
| Publisher | University of Pittsburgh |
| Source Sets | University of Pittsburgh |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.library.pitt.edu:80/ETD/available/etd-04062003-174803/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University of Pittsburgh or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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