Destruction Thresholds of Echogenic Liposomes with Clinical Diagnostic Ultrasound

Smith, Denise A. B.; Porter, Tyrone M.; Martinez, Janet; Huang, Shaoling; MacDonald, Robert C.; McPherson, David D.; Holland, Christy K.

doi:10.1016/j.ultrasmedbio.2006.11.017

Cited by 73 publications

(107 citation statements)

References 34 publications

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“…Signals in the frequency domain, S n ðxÞ, were obtained by insonifying an experimental ultrasound contrast agent, echogenic liposomes (ELIP), 37,38 in a flow phantom with spectral Doppler pulses (center frequency of 6 MHz) from a CL15-7 transducer driven by an HDI-5000 clinical scanner (Philips Medical Systems, Bothell, WA). The acoustic properties and morphology of ELIP have been recently studied by Kopechek et al 39 and Paul et al 40 ELIP are of interest for both their diagnostic 37,38,41,42 and therapeutic [43][44][45][46][47] capabilities. The flow phantom consisted of a reservoir connected to a peristaltic pump (Rabbit, Rainin, Oakland, CA), which pumped a solution of ELIP (0.1 mg/ml lipid concentration) in 0.5% (wt./vol) bovine serum albumin (Sigma-Aldrich Co., St. Louis, MO) in phosphate buffered saline (Sigma-Aldrich Co.), through a low-density polyethylene tube (2.7 mm inner diameter, 4.0 mm outer diameter, McMaster-Carr, Aurora, OH) at a 2.0 mL/min flow rate.…”

Section: A Beamforming Algorithmmentioning

confidence: 99%

Passive imaging with pulsed ultrasound insonations

Haworth¹,

Mast²,

Radhakrishnan³

et al. 2012

The Journal of the Acoustical Society of America

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117

138

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Previously, passive cavitation imaging has been described in the context of continuous-wave high-intensity focused ultrasound thermal ablation. However, the technique has potential use as a feedback mechanism for pulsed-wave therapies, such as ultrasound-mediated drug delivery. In this paper, results of experiments and simulations are reported to demonstrate the feasibility of passive cavitation imaging using pulsed ultrasound insonations and how the images depend on pulsed ultrasound parameters. The passive cavitation images were formed from channel data that was beamformed in the frequency domain. Experiments were performed in an in vitro flow phantom with an experimental echo contrast agent, echogenic liposomes, as cavitation nuclei. It was found that the pulse duration and envelope have minimal impact on the image resolution achieved. The passive cavitation image amplitude scales linearly with the cavitation emission energy. Cavitation images for both stable and inertial cavitation can be obtained from the same received data set.

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Section: A Beamforming Algorithmmentioning

confidence: 99%

Passive imaging with pulsed ultrasound insonations

Haworth¹,

Mast²,

Radhakrishnan³

et al. 2012

The Journal of the Acoustical Society of America

Self Cite

117

138

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“…Despite the detection of strong cavitation at this acoustic pressure, the precise mechanism of NO release and delivery remains unclear. Smith et al describe acoustically driven diffusion at moderate acoustic pressures, 56,57 and other investigators 7,58,59 have postulated that the lipid shell of microbubbles must first be ruptured before cavitation nucleation can occur, liberating encapsulated gas during rapid fragmentation. At a 0.34 MPa pressure exposure, it is likely that NO was released from the bubble liposomes gradually over a number of acoustic cycles.…”

Section: Ultrasound Exposure and Cavitationmentioning

confidence: 99%

Pulsed ultrasound enhances the delivery of nitric oxide from bubble liposomes to ex vivo porcine carotid tissue

Sutton¹,

Raymond²,

Verleye³

et al. 2014

IJN

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Ultrasound-mediated drug delivery is a novel technique for enhancing the penetration of drugs into diseased tissue beds noninvasively. By encapsulating drugs into microsized and nanosized liposomes, the therapeutic can be shielded from degradation within the vasculature until delivery to a target site by ultrasound exposure. Traditional in vitro or ex vivo techniques to quantify this delivery profile include optical approaches, cell culture, and electrophysiology. Here, we demonstrate an approach to characterize the degree of nitric oxide (NO) delivery to porcine carotid tissue by direct measurement of ex vivo vascular tone. An ex vivo perfusion model was adapted to assess ultrasound-mediated delivery of NO. This potent vasodilator was coencapsulated with inert octafluoropropane gas to produce acoustically active bubble liposomes. Porcine carotid arteries were excised post mortem and mounted in a physiologic buffer solution. Vascular tone was assessed in real time by coupling the artery to an isometric force transducer. NO-loaded bubble liposomes were infused into the lumen of the artery, which was exposed to 1 MHz pulsed ultrasound at a peak-to-peak acoustic pressure amplitude of 0.34 MPa. Acoustic cavitation emissions were monitored passively. Changes in vascular tone were measured and compared with control and sham NO bubble liposome exposures. Our results demonstrate that ultrasound-triggered NO release from bubble liposomes induces potent vasorelaxation within porcine carotid arteries (maximal relaxation 31%±8%), which was significantly stronger than vasorelaxation due to NO release from bubble liposomes in the absence of ultrasound (maximal relaxation 7%±3%), and comparable with relaxation due to 12 μM sodium nitroprusside infusions (maximal relaxation 32%±3%). This approach is a valuable mechanistic tool for assessing the extent of drug release and delivery to the vasculature caused by ultrasound.

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“…159 Vaporization of liquid precursors of bubble also falls in this category. 131 This regime is the most reported one in the study of bubble-cell interactions, for example: Smith et al reported sonoporation resulting from cavitation of echogenic liposomes, 123 Zhou et al used inertial cavitation to porate oocyte cells, 23 and Zhao et al used cavitation to induce cell apoptosis. 11 Using larger bubbles, Ohl et al observed two regimes of viable porated cell and detached dead cells.…”

Section: Acoustic Excitationmentioning

confidence: 99%

In vitro methods to study bubble-cell interactions: Fundamentals and therapeutic applications

et al. 2016

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Besides their use as contrast agents for ultrasound imaging, microbubbles are increasingly studied for a wide range of therapeutic applications. In particular, their ability to enhance the uptake of drugs through the permeabilization of tissues and cell membranes shows great promise. In order to fully understand the numerous paths by which bubbles can interact with cells and the even larger number of possible biological responses from the cells, thorough and extensive work is necessary. In this review, we consider the range of experimental techniques implemented in in vitro studies with the aim of elucidating these microbubble-cell interactions. First of all, the variety of cell types and cell models available are discussed, emphasizing the need for more and more complex models replicating in vivo conditions together with experimental challenges associated with this increased complexity. Second, the different types of stabilized microbubbles and more recently developed droplets and particles are presented, followed by their acoustic or optical excitation methods. Finally, the techniques exploited to study the microbubble-cell interactions are reviewed. These techniques operate over a wide range of timescales, or even off-line, revealing particular aspects or subsequent effects of these interactions. Therefore, knowledge obtained from several techniques must be combined to elucidate the underlying processes. V C 2016 AIP Publishing LLC.

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Destruction Thresholds of Echogenic Liposomes with Clinical Diagnostic Ultrasound

Cited by 73 publications

References 34 publications

Passive imaging with pulsed ultrasound insonations

Passive imaging with pulsed ultrasound insonations

Pulsed ultrasound enhances the delivery of nitric oxide from bubble liposomes to ex vivo porcine carotid tissue

In vitro methods to study bubble-cell interactions: Fundamentals and therapeutic applications

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