Influence of microbubble surface charge on capillary transit and myocardial contrast enhancement
Nicholas G. Fisher, MBBS*,
Jonathan P. Christiansen, MB, ChB*,
Alexander Klibanov, PhD*,
Ronald P. Taylor, PhD*,
Sanjiv Kaul, MD, FACC* and
Jonathan R. Lindner, MD, FACC*,*
* Cardiovascular Imaging Center, Cardiovascular Division, University of Virginia, Charlottesville, Virginia, USA
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Figure 1 Mean (± SEM) number of microbubbles retained within the cremasteric microcirculation of wild-type and C3-deficient (C3–/–) mice after injection of 3 x 107 microbubbles. *p < 0.01 all other microbubbles in wild-type mice;  p < 0.01 vs. MBneg in wild-type mice. MBneg = lipid microbubbles with a net negative charge; MBneut = lipid microbubbles with a net neutral charge; PEG = polyetheleneglycol.
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Figure 2 Size distribution of all microbubbles before injection (A) and those retained within the microcirculation (B). MBneg = lipid microbubbles with a net negative charge; MBneut = lipid microbubbles with a neutral charge; PEG = polyetheleneglycol.
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Figure 3 Examples of flow cytometry data for lipid microbubbles with a net neutral charge with polyetheleneglycol (MBneutPEG+) and lipid microbubbles with a net negative charge without polyetheleneglycol (MBnegPEG–). Histograms of green fluorescent intensity are shown for microbubbles incubated with serum and florescein isothiocyanate (FITC)-conjugated control monoclonal antibody (mAb) (A), with FITC-conjugated anti-C3b mAb alone without serum (B), or with serum and FITC-conjugated anti-C3b mAb (C). Corresponding fluorescent microscopy images from c samples are shown at the bottom (scale bars = 5 µm).
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Figure 4 Degree of C3b attachment to microbubbles, determined by mean fluorescent intensity (y-axis) measured by flow cytometry of microbubbles incubated with serum and fluorescein isothiocyanate (FITC)-conjugated anti-C3b monoclonal antibody.
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Figure 5 Examples of time versus VI curves for the right ventricular and left ventricular cavities after bolus intravenous injection of lipid microbubbles with a net neutral charge polyetheleneglycol (MBneutPEG+) (A) and lipid microbubbles with a net negative charge polyetheleneglycol (MBnegPEG–) (B). See text for details. LV = left ventricular; RV = right ventricular.
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Figure 6 Representative myocardial contrast enhancement images and time versus VI data from the anterior myocardium of one dog acquired >10 min after intravenous injections of lipid microbubbles with a net negative charge without polyetheleneglycol (MBnegPEG–) (solid circles) and lipid microbubbles with a net neutral charge with polyetheleneglycol (MBneutPEG+) (open circles). Data are shown before and after a brief high-power ultrasound sequence (HPS).
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