1
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Chen X, Chen X, Wang J, Yu FTH, Villanueva FS, Pacella JJ. Dynamic Behavior of Polymer Microbubbles During Long Ultrasound Tone-Burst Excitation and Its Application for Sonoreperfusion Therapy. ULTRASOUND IN MEDICINE & BIOLOGY 2023; 49:996-1006. [PMID: 36697268 PMCID: PMC9974862 DOI: 10.1016/j.ultrasmedbio.2022.12.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Revised: 12/19/2022] [Accepted: 12/20/2022] [Indexed: 06/17/2023]
Abstract
OBJECTIVE Ultrasound (US)-targeted microbubble (MB) cavitation (UTMC)-mediated therapies have been found to restore perfusion and enhance drug/gene delivery. Because of the potentially longer circulation time and relative ease of storage and reconstitution of polymer-shelled MBs compared with lipid MBs, we investigated the dynamic behavior of polymer microbubbles and their therapeutic potential for sonoreperfusion (SRP) therapy. METHODS The fate of polymer MBs during a single long tone-burst exposure (1 MHz, 5 ms) at various acoustic pressures and MB concentrations was recorded via high-speed microscopy and passive cavitation detection (PCD). SRP efficacy of the polymer MBs was investigated in an in vitro flow system and compared with that of lipid MBs. DISCUSSION Microscopy videos indicated that polymer MBs formed gas-filled clusters that continued to oscillate, fragment and form new gas-filled clusters during the single US burst. PCD confirmed continued acoustic activity throughout the 5-ms US excitation. SRP efficacy with polymer MBs increased with pulse duration and acoustic pressure similarly to that with lipid MBs but no significant differences were found between polymer and lipid MBs. CONCLUSION These data suggest that persistent cavitation activity from polymer MBs during long tone-burst US excitation confers excellent reperfusion efficacy.
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Affiliation(s)
- Xianghui Chen
- Center for Ultrasound Molecular Imaging and Therapeutics, University of Pittsburgh Medical Center, Pittsburgh, PA, USA; Department of Cardiology, First Affiliated Hospital of Jinan University, Guangzhou, China
| | - Xucai Chen
- Center for Ultrasound Molecular Imaging and Therapeutics, University of Pittsburgh Medical Center, Pittsburgh, PA, USA
| | - Jianjun Wang
- Center for Ultrasound Molecular Imaging and Therapeutics, University of Pittsburgh Medical Center, Pittsburgh, PA, USA
| | - Francois T H Yu
- Center for Ultrasound Molecular Imaging and Therapeutics, University of Pittsburgh Medical Center, Pittsburgh, PA, USA
| | - Flordeliza S Villanueva
- Center for Ultrasound Molecular Imaging and Therapeutics, University of Pittsburgh Medical Center, Pittsburgh, PA, USA
| | - John J Pacella
- Center for Ultrasound Molecular Imaging and Therapeutics, University of Pittsburgh Medical Center, Pittsburgh, PA, USA.
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2
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Zhao X, Wright A, Goertz DE. An optical and acoustic investigation of microbubble cavitation in small channels under therapeutic ultrasound conditions. ULTRASONICS SONOCHEMISTRY 2023; 93:106291. [PMID: 36640460 PMCID: PMC9852793 DOI: 10.1016/j.ultsonch.2023.106291] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Revised: 12/22/2022] [Accepted: 01/04/2023] [Indexed: 06/04/2023]
Abstract
Therapeutic focused ultrasound in combination with encapsulated microbubbles is being widely investigated for its ability to elicit bioeffects in the microvasculature, such as transient permeabilization for drug delivery or at higher pressures to achieve 'antivascular' effects. While it is well established that the behaviors of microbubbles are altered when they are situated within sufficiently small vessels, there is a paucity of data examining how the bubble population dynamics and emissions change as a function of channel (vessel) diameter over a size range relevant to therapeutic ultrasound, particularly at pressures relevant to antivascular ultrasound. Here we use acoustic emissions detection and high-speed microscopy (10 kframes/s) to examine the behavior of a polydisperse clinically employed agent (Definity®) in wall-less channels as their diameters are scaled from 1200 to 15 µm. Pressures are varied from 0.1 to 3 MPa using either a 5 ms pulse or a sequence of 0.1 ms pulses spaced at 1 ms, both of which have been previously employed in an in vivo context. With increasing pressure, the 1200 µm channel - on the order of small arteries and veins - exhibited inertial cavitation, 1/2 subharmonics and 3/2 ultraharmonics, consistent with numerous previous reports. The 200 and 100 µm channels - in the size range of larger microvessels less affected by therapeutic focused ultrasound - exhibited a distinctly different behavior, having muted development of 1/2 subharmonics and 3/2 ultraharmonics and reduced persistence. These were associated with radiation forces displacing bubbles to the distal wall and inducing clusters that then rapidly dissipated along with emissions. As the diameter transitioned to 50 and then 15 µm - a size regime that is most relevant to therapeutic focused ultrasound - there was a higher threshold for the onset of inertial cavitation as well as subharmonics and ultraharmonics, which importantly had more complex orders that are not normally reported. Clusters also occurred in these channels (e.g. at 3 MPa, the mean lateral and axial sizes were 23 and 72 µm in the 15 µm channel; 50 and 90 µm in the 50 µm channel), however in this case they occupied the entire lumens and displaced the wall boundaries. Damage to the 15 µm channel was observed for both pulse types, but at a lower pressure for the long pulse. Experiments conducted with a 'nanobubble' (<0.45 µm) subpopulation of Definity followed broadly similar features to 'native' Definity, albeit at a higher pressure threshold for inertial cavitation. These results provide new insights into the behavior of microbubbles in small vessels at higher pressures and have implications for therapeutic focused ultrasound cavitation monitoring and control.
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Affiliation(s)
- Xiaoxiao Zhao
- Department of Medical Biophysics, University of Toronto, M5G 1L7, Canada; Sunnybrook Research Institute, 2075 Bayview Ave, Toronto M4N 3M5, Canada.
| | - Alex Wright
- Sunnybrook Research Institute, 2075 Bayview Ave, Toronto M4N 3M5, Canada
| | - David E Goertz
- Department of Medical Biophysics, University of Toronto, M5G 1L7, Canada; Sunnybrook Research Institute, 2075 Bayview Ave, Toronto M4N 3M5, Canada.
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3
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Li H, Li X, Collado-Lara G, Lattwein KR, Mastik F, Beurskens R, van der Steen AFW, Verweij MD, de Jong N, Kooiman K. Coupling Two Ultra-high-Speed Cameras to Elucidate Ultrasound Contrast-Mediated Imaging and Therapy. ULTRASOUND IN MEDICINE & BIOLOGY 2023; 49:388-397. [PMID: 36241587 DOI: 10.1016/j.ultrasmedbio.2022.08.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Revised: 08/26/2022] [Accepted: 08/31/2022] [Indexed: 06/16/2023]
Abstract
Ultrasound contrast-mediated medical imaging and therapy both rely on the dynamics of micron- and nanometer-sized ultrasound cavitation nuclei, such as phospholipid-coated microbubbles and phase-change droplets. Ultrasound cavitation nuclei respond non-linearly to ultrasound on a nanosecond time scale that necessitates the use of ultra-high-speed imaging to fully visualize these dynamics in detail. In this study, we developed an ultra-high-speed optical imaging system that can record up to 20 million frames per second (Mfps) by coupling two small-sized, commercially available, 10-Mfps cameras. The timing and reliability of the interleaved cameras needed to achieve 20 Mfps was validated using two synchronized light-emitting diode strobe lights. Once verified, ultrasound-activated microbubble responses were recorded and analyzed. A unique characteristic of this coupled system is its ability to be reconfigured to provide orthogonal observations at 10 Mfps. Acoustic droplet vaporization was imaged from two orthogonal views, by which the 3-D dynamics of the phase transition could be visualized. This optical imaging system provides the temporal resolution and experimental flexibility needed to further elucidate the dynamics of ultrasound cavitation nuclei to potentiate the clinical translation of ultrasound-mediated imaging and therapy developments.
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Affiliation(s)
- Hongchen Li
- Department of Biomedical Engineering, Thoraxcenter, Erasmus MC University Medical Center Rotterdam, Rotterdam, The Netherlands.
| | - Xiufeng Li
- Section of Medical Imaging, Department of Imaging Physics, Delft University of Technology, Delft, The Netherlands
| | - Gonzalo Collado-Lara
- Department of Biomedical Engineering, Thoraxcenter, Erasmus MC University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Kirby R Lattwein
- Department of Biomedical Engineering, Thoraxcenter, Erasmus MC University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Frits Mastik
- Department of Biomedical Engineering, Thoraxcenter, Erasmus MC University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Robert Beurskens
- Department of Biomedical Engineering, Thoraxcenter, Erasmus MC University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Antonius F W van der Steen
- Department of Biomedical Engineering, Thoraxcenter, Erasmus MC University Medical Center Rotterdam, Rotterdam, The Netherlands; Section of Medical Imaging, Department of Imaging Physics, Delft University of Technology, Delft, The Netherlands
| | - Martin D Verweij
- Department of Biomedical Engineering, Thoraxcenter, Erasmus MC University Medical Center Rotterdam, Rotterdam, The Netherlands; Section of Medical Imaging, Department of Imaging Physics, Delft University of Technology, Delft, The Netherlands
| | - Nico de Jong
- Department of Biomedical Engineering, Thoraxcenter, Erasmus MC University Medical Center Rotterdam, Rotterdam, The Netherlands; Section of Medical Imaging, Department of Imaging Physics, Delft University of Technology, Delft, The Netherlands
| | - Klazina Kooiman
- Department of Biomedical Engineering, Thoraxcenter, Erasmus MC University Medical Center Rotterdam, Rotterdam, The Netherlands
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4
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Zeng P, Chen C, Lof J, Stolze E, Li S, Chen X, Pacella J, Villanueva FS, Matsunaga T, Everbach EC, Fei H, Xie F, Porter T. Acoustic Detection of Retained Perfluoropropane Droplets Within the Developing Myocardial Infarct Zone. ULTRASOUND IN MEDICINE & BIOLOGY 2022; 48:2322-2334. [PMID: 36050231 PMCID: PMC9547398 DOI: 10.1016/j.ultrasmedbio.2022.07.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 07/11/2022] [Accepted: 07/12/2022] [Indexed: 06/15/2023]
Abstract
Perfluoropropane droplets (PDs) cross endothelial barriers and can be acoustically activated for selective myocardial extravascular enhancement following intravenous injection (IVI). Our objective was to determine how to optimally activate extravascular PDs for transthoracic ultrasound-enhanced delineation of a developing scar zone (DSZ). Ultrafast-frame-rate microscopy was conducted to determine the effect of pulse sequence on the threshold of bubble formation from PDs. In vitro studies were subsequently performed at different flow rates to determine acoustic activation and inertial cavitation thresholds for a PD infusion using multipulse fundamental non-linear or single-pulse harmonic imaging. IVIs of PDs were given in 9 rats and 10 pigs following prolonged left anterior descending ischemia to detect and quantify PD kinetics within the DSZ. A multipulse sequence had a lower myocardial index threshold for acoustic activation by ultrafast-frame-rate microscopy. Acoustic activation was observed at a myocardial index ≥0.4 below the inertial cavitation threshold for both pulse sequences. In rats, confocal microscopy and serial acoustic activation imaging detected higher droplet presence (relative to remote regions) within the DSZ at 3 min post-IVI. Transthoracic high-mechanical-index impulses with fundamental non-linear imaging in pigs at this time post-IVI resulted in selective contrast enhancement within the DSZ.
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Affiliation(s)
- Ping Zeng
- Department of Cardiology, Guangdong Cardiovascular Institute, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangzhou, China; Division of Cardiovascular Medicine, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Cheng Chen
- Center for Ultrasound Molecular Imaging and Therapeutics, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - John Lof
- Division of Cardiovascular Medicine, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Elizabeth Stolze
- Division of Cardiovascular Medicine, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Shouqiang Li
- Division of Cardiovascular Medicine, University of Nebraska Medical Center, Omaha, Nebraska, USA; Department of Ultrasound, Second Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Xucai Chen
- Center for Ultrasound Molecular Imaging and Therapeutics, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - John Pacella
- Center for Ultrasound Molecular Imaging and Therapeutics, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Flordeliza S Villanueva
- Center for Ultrasound Molecular Imaging and Therapeutics, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Terry Matsunaga
- Department of Biomedical Engineering, University of Arizona, Tucson, Arizona, USA; Department of Medical Imaging, University of Arizona, Tucson, Arizona, USA
| | | | - Hongwen Fei
- Department of Cardiology, Guangdong Cardiovascular Institute, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangzhou, China
| | - Feng Xie
- Division of Cardiovascular Medicine, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Thomas Porter
- Division of Cardiovascular Medicine, University of Nebraska Medical Center, Omaha, Nebraska, USA.
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5
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van Wamel A, Mühlenpfordt M, Hansen R, Healey A, Villanueva FS, Kotopoulis S, Davies CDL, Chen X. Ultrafast Microscopy Imaging of Acoustic Cluster Therapy Bubbles: Activation and Oscillation. ULTRASOUND IN MEDICINE & BIOLOGY 2022; 48:1840-1857. [PMID: 35773079 DOI: 10.1016/j.ultrasmedbio.2022.05.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Revised: 02/15/2022] [Accepted: 05/10/2022] [Indexed: 06/15/2023]
Abstract
Acoustic Cluster Therapy (ACT®) is a platform for improving drug delivery and has had promising pre-clinical results. A clinical trial is ongoing. ACT® is based on microclusters of microbubbles-microdroplets that, when sonicated, form a large ACT® bubble. The aim of this study was to obtain new knowledge on the dynamic formation and oscillations of ACT® bubbles by ultrafast optical imaging in a microchannel. The high-speed recordings revealed the microbubble-microdroplet fusion, and the gas in the microbubble acted as a vaporization seed for the microdroplet. Subsequently, the bubble grew by gas diffusion from the surrounding medium and became a large ACT® bubble with a diameter of 5-50 μm. A second ultrasound exposure at lower frequency caused the ACT® bubble to oscillate. The recorded oscillations were compared with simulations using the modified Rayleigh-Plesset equation. A term accounting for the physical boundary imposed by the microchannel wall was included. The recorded oscillation amplitudes were approximately 1-2 µm, hence similar to oscillations of smaller contrast agent microbubbles. These findings, together with our previously reported promising pre-clinical therapeutic results, suggest that these oscillations covering a large part of the vessel wall because of the large bubble volume can substantially improve therapeutic outcome.
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Affiliation(s)
- Annemieke van Wamel
- Department of Physics, Norwegian University of Science and Technology, Trondheim, Norway
| | - Melina Mühlenpfordt
- Department of Physics, Norwegian University of Science and Technology, Trondheim, Norway
| | - Rune Hansen
- Department of Health Research, SINTEF Digital, Trondheim, Norway; Department of Circulation and Medical Imaging, Norwegian University of Science and Technology, Trondheim, Norway
| | | | - Flordeliza S Villanueva
- Center for Ultrasound Molecular Imaging and Therapeutics, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Spiros Kotopoulis
- Department of Physics, Norwegian University of Science and Technology, Trondheim, Norway; Department of Clinical Medicine, University of Bergen, Bergen, Norway
| | | | - Xucai Chen
- Center for Ultrasound Molecular Imaging and Therapeutics, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
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6
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Beekers I, Langeveld SAG, Meijlink B, van der Steen AFW, de Jong N, Verweij MD, Kooiman K. Internalization of targeted microbubbles by endothelial cells and drug delivery by pores and tunnels. J Control Release 2022; 347:460-475. [PMID: 35545132 DOI: 10.1016/j.jconrel.2022.05.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 04/09/2022] [Accepted: 05/03/2022] [Indexed: 12/15/2022]
Abstract
Ultrasound insonification of microbubbles can locally enhance drug delivery by increasing the cell membrane permeability. To aid development of a safe and effective therapeutic microbubble, more insight into the microbubble-cell interaction is needed. In this in vitro study we aimed to investigate the initial 3D morphology of the endothelial cell membrane adjacent to individual microbubbles (n = 301), determine whether this morphology was affected upon binding and by the type of ligand on the microbubble, and study its influence on microbubble oscillation and the drug delivery outcome. High-resolution 3D confocal microscopy revealed that targeted microbubbles were internalized by endothelial cells, while this was not the case for non-targeted or IgG1-κ control microbubbles. The extent of internalization was ligand-dependent, since αvβ3-targeted microbubbles were significantly more internalized than CD31-targeted microbubbles. Ultra-high-speed imaging (~17 Mfps) in combination with high-resolution confocal microscopy (n = 246) showed that microbubble internalization resulted in a damped microbubble oscillation upon ultrasound insonification (2 MHz, 200 kPa peak negative pressure, 10 cycles). Despite damped oscillation, the cell's susceptibility to sonoporation (as indicated by PI uptake) was increased for internalized microbubbles. Monitoring cell membrane integrity (n = 230) showed the formation of either a pore, for intracellular delivery, or a tunnel (i.e. transcellular perforation), for transcellular delivery. Internalized microbubbles caused fewer transcellular perforations and smaller pore areas than non-internalized microbubbles. In conclusion, studying microbubble-mediated drug delivery using a state-of-the-art imaging system revealed receptor-mediated microbubble internalization and its effect on microbubble oscillation and resulting membrane perforation by pores and tunnels.
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Affiliation(s)
- Inés Beekers
- Department of Biomedical Engineering, Thoraxcenter, Erasmus MC University Medical Center Rotterdam, Office Ee2302, P.O. Box 2040, 3000 CA Rotterdam, the Netherlands; Department of Health, ORTEC B.V., Houtsingel 5, 2719 EA Zoetermeer, the Netherlands.
| | - Simone A G Langeveld
- Department of Biomedical Engineering, Thoraxcenter, Erasmus MC University Medical Center Rotterdam, Office Ee2302, P.O. Box 2040, 3000 CA Rotterdam, the Netherlands
| | - Bram Meijlink
- Department of Biomedical Engineering, Thoraxcenter, Erasmus MC University Medical Center Rotterdam, Office Ee2302, P.O. Box 2040, 3000 CA Rotterdam, the Netherlands
| | - Antonius F W van der Steen
- Department of Biomedical Engineering, Thoraxcenter, Erasmus MC University Medical Center Rotterdam, Office Ee2302, P.O. Box 2040, 3000 CA Rotterdam, the Netherlands
| | - Nico de Jong
- Department of Biomedical Engineering, Thoraxcenter, Erasmus MC University Medical Center Rotterdam, Office Ee2302, P.O. Box 2040, 3000 CA Rotterdam, the Netherlands; Laboratory of Medical Imaging, Department of Imaging Physics, Delft University of Technology, Building 22, Room D218, Lorentzweg 1, 2628 CJ Delft, the Netherlands
| | - Martin D Verweij
- Department of Biomedical Engineering, Thoraxcenter, Erasmus MC University Medical Center Rotterdam, Office Ee2302, P.O. Box 2040, 3000 CA Rotterdam, the Netherlands; Laboratory of Medical Imaging, Department of Imaging Physics, Delft University of Technology, Building 22, Room D218, Lorentzweg 1, 2628 CJ Delft, the Netherlands
| | - Klazina Kooiman
- Department of Biomedical Engineering, Thoraxcenter, Erasmus MC University Medical Center Rotterdam, Office Ee2302, P.O. Box 2040, 3000 CA Rotterdam, the Netherlands
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7
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Vancomycin-decorated microbubbles as a theranostic agent for Staphylococcus aureus biofilms. Int J Pharm 2021; 609:121154. [PMID: 34624449 DOI: 10.1016/j.ijpharm.2021.121154] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2021] [Revised: 09/28/2021] [Accepted: 09/30/2021] [Indexed: 12/20/2022]
Abstract
Bacterial biofilms are a huge burden on our healthcare systems worldwide. The lack of specificity in diagnostic and treatment possibilities result in difficult-to-treat and persistent infections. The aim of this in vitro study was to investigate if microbubbles targeted specifically to bacteria in biofilms could be used both for diagnosis as well for sonobactericide treatment and demonstrate their theranostic potential for biofilm infection management. The antibiotic vancomycin was chemically coupled to the lipid shell of microbubbles and validated using mass spectrometry and high-axial resolution 4Pi confocal microscopy. Theranostic proof-of-principle was investigated by demonstrating the specific binding of vancomycin-decorated microbubbles (vMB) to statically and flow grown Staphylococcus aureus (S. aureus) biofilms under increasing shear stress flow conditions (0-12 dyn/cm2), as well as confirmation of microbubble oscillation and biofilm disruption upon ultrasound exposure (2 MHz, 250 kPa, and 5,000 or 10,000 cycles) during flow shear stress of 5 dyn/cm2 using time-lapse confocal microscopy combined with the Brandaris 128 ultra-high-speed camera. Vancomycin was successfully incorporated into the microbubble lipid shell. vMB bound significantly more often than control microbubbles to biofilms, also in the presence of free vancomycin (up to 1000 µg/mL) and remained bound under increasing shear stress flow conditions (up to 12 dyn/cm2). Upon ultrasound insonification biofilm area was reduced of up to 28%, as confirmed by confocal microscopy. Our results confirm the successful production of vMB and support their potential as a new theranostic tool for S. aureus biofilm infections by allowing for specific bacterial detection and biofilm disruption.
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8
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Rong N, Zhang M, Wang Y, Wu H, Qi H, Fu X, Li D, Yang C, Wang Y, Fan Z. Effects of extracellular matrix rigidity on sonoporation facilitated by targeted microbubbles: Bubble attachment, bubble dynamics, and cell membrane permeabilization. ULTRASONICS SONOCHEMISTRY 2020; 67:105125. [PMID: 32298974 DOI: 10.1016/j.ultsonch.2020.105125] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Revised: 02/19/2020] [Accepted: 04/07/2020] [Indexed: 06/11/2023]
Abstract
In this study, we investigated the effects of extracellular matrix rigidity, an important physical property of microenvironments regulating cell morphology and functions, on sonoporation facilitated by targeted microbubbles, highlighting the role of microbubbles. We conducted mechanistic studies at the cellular level on physiologically relevant soft and rigid substrates. By developing a unique imaging strategy, we first resolved details of the 3D attachment configurations between targeted microbubbles and cell membrane. High-speed video microscopy then unveiled bubble dynamics driven by a single ultrasound pulse. Finally, we evaluated the cell membrane permeabilization using a small molecule model drug. Our results demonstrate that: (1) stronger targeted microbubble attachment was formed for cells cultured on the rigid substrate, while six different attachment configurations were revealed in total; (2) more violent bubble oscillation was observed for cells cultured on the rigid substrate, while one third of bubbles attached to cells on the soft substrate exhibited deformation shortly after ultrasound was turned off; (3) higher acoustic pressure was needed to permeabilize the cell membrane for cells on the soft substrate, while under the same ultrasound condition, acoustically-activated microbubbles generated larger pores as compared to cells cultured on the soft substrate. The current findings provide new insights to understand the underlying mechanisms of sonoporation in a physiologically relevant context and may be useful for the clinical translation of sonoporation.
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Affiliation(s)
- Ning Rong
- Department of Biomedical Engineering, School of Precision Instruments and Opto-Electronics Engineering, Tianjin University, Tianjin 300072, China
| | - Meiru Zhang
- Department of Biomedical Engineering, School of Precision Instruments and Opto-Electronics Engineering, Tianjin University, Tianjin 300072, China
| | - Yulin Wang
- Department of Biomedical Engineering, School of Precision Instruments and Opto-Electronics Engineering, Tianjin University, Tianjin 300072, China
| | - Hao Wu
- State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Tianjin 300072, China
| | - Hui Qi
- State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Tianjin 300072, China
| | - Xing Fu
- State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Tianjin 300072, China
| | - Dachao Li
- State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Tianjin 300072, China
| | - Chunmei Yang
- Department of Biomedical Engineering, School of Precision Instruments and Opto-Electronics Engineering, Tianjin University, Tianjin 300072, China
| | - Yan Wang
- Department of Biomedical Engineering, School of Precision Instruments and Opto-Electronics Engineering, Tianjin University, Tianjin 300072, China
| | - Zhenzhen Fan
- Department of Biomedical Engineering, School of Precision Instruments and Opto-Electronics Engineering, Tianjin University, Tianjin 300072, China; State Key Laboratory of Acoustics, Institute of Acoustics, Chinese Academy of Sciences, Beijing 100190, China.
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9
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Beekers I, Mastik F, Beurskens R, Tang PY, Vegter M, van der Steen AFW, de Jong N, Verweij MD, Kooiman K. High-Resolution Imaging of Intracellular Calcium Fluctuations Caused by Oscillating Microbubbles. ULTRASOUND IN MEDICINE & BIOLOGY 2020; 46:2017-2029. [PMID: 32402676 DOI: 10.1016/j.ultrasmedbio.2020.03.029] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Revised: 03/11/2020] [Accepted: 03/26/2020] [Indexed: 06/11/2023]
Abstract
Ultrasound insonification of microbubbles can locally enhance drug delivery, but the microbubble-cell interaction remains poorly understood. Because intracellular calcium (Cai2+) is a key cellular regulator, unraveling the Cai2+ fluctuations caused by an oscillating microbubble provides crucial insight into the underlying bio-effects. Therefore, we developed an optical imaging system at nanometer and nanosecond resolution that can resolve Cai2+ fluctuations and microbubble oscillations. Using this system, we clearly distinguished three Cai2+ uptake profiles upon sonoporation of endothelial cells, which strongly correlated with the microbubble oscillation amplitude, severity of sonoporation and opening of cell-cell contacts. We found a narrow operating range for viable drug delivery without lethal cell damage. Moreover, adjacent cells were affected by a calcium wave propagating at 15 μm/s. With the unique optical system, we unraveled the microbubble oscillation behavior required for drug delivery and Cai2+ fluctuations, providing new insight into the microbubble-cell interaction to aid clinical translation.
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Affiliation(s)
- Inés Beekers
- Department of Biomedical Engineering, Thoraxcenter, Erasmus University Medical Center, Rotterdam, The Netherlands.
| | - Frits Mastik
- Department of Biomedical Engineering, Thoraxcenter, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Robert Beurskens
- Department of Biomedical Engineering, Thoraxcenter, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Phoei Ying Tang
- Department of Biomedical Engineering, Thoraxcenter, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Merel Vegter
- Department of Biomedical Engineering, Thoraxcenter, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Antonius F W van der Steen
- Department of Biomedical Engineering, Thoraxcenter, Erasmus University Medical Center, Rotterdam, The Netherlands; Laboratory of Acoustical Wavefield Imaging, Department of Imaging Physics, Delft University of Technology, Delft, The Netherlands
| | - Nico de Jong
- Department of Biomedical Engineering, Thoraxcenter, Erasmus University Medical Center, Rotterdam, The Netherlands; Laboratory of Acoustical Wavefield Imaging, Department of Imaging Physics, Delft University of Technology, Delft, The Netherlands
| | - Martin D Verweij
- Department of Biomedical Engineering, Thoraxcenter, Erasmus University Medical Center, Rotterdam, The Netherlands; Laboratory of Acoustical Wavefield Imaging, Department of Imaging Physics, Delft University of Technology, Delft, The Netherlands
| | - Klazina Kooiman
- Department of Biomedical Engineering, Thoraxcenter, Erasmus University Medical Center, Rotterdam, The Netherlands
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10
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Beekers I, Lattwein KR, Kouijzer JJP, Langeveld SAG, Vegter M, Beurskens R, Mastik F, Verduyn Lunel R, Verver E, van der Steen AFW, de Jong N, Kooiman K. Combined Confocal Microscope and Brandaris 128 Ultra-High-Speed Camera. ULTRASOUND IN MEDICINE & BIOLOGY 2019; 45:2575-2582. [PMID: 31262523 DOI: 10.1016/j.ultrasmedbio.2019.06.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Revised: 05/23/2019] [Accepted: 06/05/2019] [Indexed: 06/09/2023]
Abstract
Controlling microbubble-mediated drug delivery requires the underlying biological and physical mechanisms to be unraveled. To image both microbubble oscillation upon ultrasound insonification and the resulting cellular response, we developed an optical imaging system that can achieve the necessary nanosecond temporal and nanometer spatial resolutions. We coupled the Brandaris 128 ultra-high-speed camera (up to 25 million frames per second) to a custom-built Nikon A1R+ confocal microscope. The unique capabilities of this combined system are demonstrated with three experiments showing microbubble oscillation leading to either endothelial drug delivery, bacterial biofilm disruption, or structural changes in the microbubble coating. In conclusion, using this state-of-the-art optical imaging system, microbubble-mediated drug delivery can be studied with high temporal resolution to resolve microbubble oscillation and high spatial resolution and detector sensitivity to discern cellular response. Combining these two imaging technologies will substantially advance our knowledge on microbubble behavior and its role in drug delivery.
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Affiliation(s)
- Inés Beekers
- Department of Biomedical Engineering, Thoraxcenter, Erasmus MC, Rotterdam, The Netherlands.
| | - Kirby R Lattwein
- Department of Biomedical Engineering, Thoraxcenter, Erasmus MC, Rotterdam, The Netherlands
| | - Joop J P Kouijzer
- Department of Biomedical Engineering, Thoraxcenter, Erasmus MC, Rotterdam, The Netherlands
| | - Simone A G Langeveld
- Department of Biomedical Engineering, Thoraxcenter, Erasmus MC, Rotterdam, The Netherlands
| | - Merel Vegter
- Department of Biomedical Engineering, Thoraxcenter, Erasmus MC, Rotterdam, The Netherlands
| | - Robert Beurskens
- Department of Biomedical Engineering, Thoraxcenter, Erasmus MC, Rotterdam, The Netherlands
| | - Frits Mastik
- Department of Biomedical Engineering, Thoraxcenter, Erasmus MC, Rotterdam, The Netherlands
| | | | - Emma Verver
- Nikon Netherlands, Amsterdam, The Netherlands
| | - Antonius F W van der Steen
- Department of Biomedical Engineering, Thoraxcenter, Erasmus MC, Rotterdam, The Netherlands; Laboratory of Acoustical Wavefield Imaging, Delft University of Technology, Delft, The Netherlands
| | - Nico de Jong
- Department of Biomedical Engineering, Thoraxcenter, Erasmus MC, Rotterdam, The Netherlands; Laboratory of Acoustical Wavefield Imaging, Delft University of Technology, Delft, The Netherlands
| | - Klazina Kooiman
- Department of Biomedical Engineering, Thoraxcenter, Erasmus MC, Rotterdam, The Netherlands
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11
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Pourtabrizi M, Shahtahmassebi N, Kompany A, Sharifi S. Effect of Microemulsion Structure on Fluorescence and Nonlinear Optical Properties of Rhodamine 6G. J Fluoresc 2017; 28:323-336. [DOI: 10.1007/s10895-017-2195-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2017] [Accepted: 11/07/2017] [Indexed: 10/18/2022]
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12
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Helfield BL, Chen X, Qin B, Watkins SC, Villanueva FS. Mechanistic Insight into Sonoporation with Ultrasound-Stimulated Polymer Microbubbles. ULTRASOUND IN MEDICINE & BIOLOGY 2017; 43:2678-2689. [PMID: 28847500 PMCID: PMC5644032 DOI: 10.1016/j.ultrasmedbio.2017.07.017] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Revised: 07/19/2017] [Accepted: 07/22/2017] [Indexed: 05/06/2023]
Abstract
Sonoporation is emerging as a feasible, non-viral gene delivery platform for the treatment of cardiovascular disease and cancer. Despite promising results, this approach remains less efficient than viral methods. The objective of this work is to help substantiate the merit of polymeric microbubble sonoporation as a non-viral, localized cell permeation and payload delivery strategy by taking a ground-up approach to elucidating the fundamental mechanisms at play. In this study, we apply simultaneous microscopy of polymeric microbubble sonoporation over its intrinsic biophysical timescales-with sub-microsecond resolution to examine microbubble cavitation and millisecond resolution over several minutes to examine local macromolecule uptake through enhanced endothelial cell membrane permeability-bridging over six orders of magnitude in time. We quantified microbubble behavior and resulting sonoporation thresholds at transmit frequencies of 0.5, 1 and 2 MHz, and determined that sonic cracking is a necessary but insufficient condition to induce sonoporation. Further, sonoporation propensity increases with the extent of sonic cracking, namely, from partial to complete gas escape from the polymeric encapsulation. For the subset that exhibited complete gas escape from sonic cracking, a proportional relationship between the maximum projected gas area and resulting macromolecule uptake was observed. These results have revealed one aspect of polymeric bubble activity on the microsecond time scale that is associated with eliciting sonoporation in adjacent endothelial cells, and contributes toward an understanding of the physical rationale for sonoporation with polymer-encapsulated microbubble contrast agents.
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Affiliation(s)
- Brandon L Helfield
- Center for Ultrasound Molecular Imaging and Therapeutics, University of Pittsburgh, Pittsburgh, Pennsylvania, USA; Heart and Vascular Institute, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA; Pittsburgh Heart, Lung, Blood and Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, Pennsylvania, USA; Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Xucai Chen
- Center for Ultrasound Molecular Imaging and Therapeutics, University of Pittsburgh, Pittsburgh, Pennsylvania, USA; Heart and Vascular Institute, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA; Pittsburgh Heart, Lung, Blood and Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, Pennsylvania, USA; Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Bin Qin
- Center for Ultrasound Molecular Imaging and Therapeutics, University of Pittsburgh, Pittsburgh, Pennsylvania, USA; Heart and Vascular Institute, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA; Pittsburgh Heart, Lung, Blood and Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, Pennsylvania, USA; Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Simon C Watkins
- Center for Biologic Imaging, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA; Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Flordeliza S Villanueva
- Center for Ultrasound Molecular Imaging and Therapeutics, University of Pittsburgh, Pittsburgh, Pennsylvania, USA; Heart and Vascular Institute, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA; Pittsburgh Heart, Lung, Blood and Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, Pennsylvania, USA; Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
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13
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Kooiman K, van Rooij T, Qin B, Mastik F, Vos HJ, Versluis M, Klibanov AL, de Jong N, Villanueva FS, Chen X. Focal areas of increased lipid concentration on the coating of microbubbles during short tone-burst ultrasound insonification. PLoS One 2017; 12:e0180747. [PMID: 28686673 PMCID: PMC5501608 DOI: 10.1371/journal.pone.0180747] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Accepted: 06/20/2017] [Indexed: 01/13/2023] Open
Abstract
Acoustic behavior of lipid-coated microbubbles has been widely studied, which has led to several numerical microbubble dynamics models that incorporate lipid coating behavior, such as buckling and rupture. In this study we investigated the relationship between microbubble acoustic and lipid coating behavior on a nanosecond scale by using fluorescently labeled lipids. It is hypothesized that a local increased concentration of lipids, appearing as a focal area of increased fluorescence intensity (hot spot) in the fluorescence image, is related to buckling and folding of the lipid layer thereby highly influencing the microbubble acoustic behavior. To test this hypothesis, the lipid microbubble coating was fluorescently labeled. The vibration of the microbubble (n = 177; 2.3–10.3 μm in diameter) upon insonification at an ultrasound frequency of 0.5 or 1 MHz at 25 or 50 kPa acoustic pressure was recorded with the UPMC Cam, an ultra-high-speed fluorescence camera, operated at ~4–5 million frames per second. During short tone-burst excitation, hot spots on the microbubble coating occurred at relative vibration amplitudes > 0.3 irrespective of frequency and acoustic pressure. Around resonance, the majority of the microbubbles formed hot spots. When the microbubble also deflated acoustically, hot spot formation was likely irreversible. Although compression-only behavior (defined as substantially more microbubble compression than expansion) and subharmonic responses were observed in those microbubbles that formed hot spots, both phenomena were also found in microbubbles that did not form hot spots during insonification. In conclusion, this study reveals hot spot formation of the lipid monolayer in the microbubble’s compression phase. However, our experimental results show that there is no direct relationship between hot spot formation of the lipid coating and microbubble acoustic behaviors such as compression-only and the generation of a subharmonic response. Hence, our hypothesis that hot spots are related to acoustic buckling could not be verified.
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Affiliation(s)
- Klazina Kooiman
- Center for Ultrasound Molecular Imaging and Therapeutics, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States of America
- Netherlands Heart Institute, Utrecht, the Netherlands
- Department of Biomedical Engineering, Thoraxcenter, Erasmus MC, Rotterdam, the Netherlands
- * E-mail:
| | - Tom van Rooij
- Department of Biomedical Engineering, Thoraxcenter, Erasmus MC, Rotterdam, the Netherlands
| | - Bin Qin
- Center for Ultrasound Molecular Imaging and Therapeutics, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States of America
| | - Frits Mastik
- Department of Biomedical Engineering, Thoraxcenter, Erasmus MC, Rotterdam, the Netherlands
| | - Hendrik J. Vos
- Department of Biomedical Engineering, Thoraxcenter, Erasmus MC, Rotterdam, the Netherlands
- Laboratory of Acoustical Wavefield Imaging, Faculty of Applied Sciences, Delft University of Technology, Delft, the Netherlands
| | - Michel Versluis
- Physics of Fluids Group, MIRA Institute for Biomedical Technology and Technical Medicine and MESA+ Institute for Nanotechnology, University of Twente, Enschede, the Netherlands
| | - Alexander L. Klibanov
- Cardiovascular Division, Department of Medicine, University of Virginia, Charlottesville, Virginia, United States of America
| | - Nico de Jong
- Department of Biomedical Engineering, Thoraxcenter, Erasmus MC, Rotterdam, the Netherlands
- Laboratory of Acoustical Wavefield Imaging, Faculty of Applied Sciences, Delft University of Technology, Delft, the Netherlands
| | - Flordeliza S. Villanueva
- Center for Ultrasound Molecular Imaging and Therapeutics, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States of America
| | - Xucai Chen
- Center for Ultrasound Molecular Imaging and Therapeutics, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States of America
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14
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Goyal A, Yu FTH, Tenwalde MG, Chen X, Althouse A, Villanueva FS, Pacella JJ. Inertial Cavitation Ultrasound with Microbubbles Improves Reperfusion Efficacy When Combined with Tissue Plasminogen Activator in an In Vitro Model of Microvascular Obstruction. ULTRASOUND IN MEDICINE & BIOLOGY 2017; 43:1391-1400. [PMID: 28395964 PMCID: PMC5440195 DOI: 10.1016/j.ultrasmedbio.2017.02.013] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Revised: 02/10/2017] [Accepted: 02/18/2017] [Indexed: 05/14/2023]
Abstract
We have previously reported that long-tone-burst, high-mechanical-index ultrasound (US) and microbubble (MB) therapy can restore perfusion in both in vitro and in vivo models of microvascular obstruction (MVO). Addition of MBs to US has been found to potentiate the efficacy of thrombolytics on large venous thrombi; however, the optimal US parameters for achieving microvascular reperfusion of MVO caused by microthrombi, when combined with tissue plasminogen activator (tPA), are unknown. We sought to elucidate the specific effects of US, with and without tPA, for effective reperfusion of MVO in an in vitro model using both venous and arterial microthrombi. Venous- and arterial-type microthrombi were infused onto a mesh with 40-μm pores to simulate MVO. Pulsed US (1 MHz) was delivered with inertial cavitation (IC) (1.0 MPa, 1000 cycles, 0.33 Hz) and stable cavitation (SC) US (0.23 MPa, 20% duty cycle, 0.33 Hz) regimes while MB suspension (2 × 106 MBs/mL) was infused. The efficacy of sonoreperfusion with these parameters was tested with and without tPA. Sonoreperfusion efficacy was significantly greater for IC + tPA compared with tPA alone, IC, SC and SC + tPA, suggesting lytic synergism between tPA and US for both venous- and arterial-type microthrombi. In contrast to our previous in vitro studies using 1.5 MPa at 5000 US cycles without tPA, the IC regime employed herein used 90% less US energy. These findings suggest an IC regime can be used with tPA synergistically to achieve a high degree of fibrinolysis for both thrombus types.
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Affiliation(s)
- Akash Goyal
- Center for Ultrasound Molecular Imaging and Therapeutics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Francois T H Yu
- Center for Ultrasound Molecular Imaging and Therapeutics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Mathea G Tenwalde
- Center for Ultrasound Molecular Imaging and Therapeutics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Xucai Chen
- Center for Ultrasound Molecular Imaging and Therapeutics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Andrew Althouse
- Clinical Biostatistics Core, Heart and Vascular Institute, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA
| | - Flordeliza S Villanueva
- Center for Ultrasound Molecular Imaging and Therapeutics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - John J Pacella
- Center for Ultrasound Molecular Imaging and Therapeutics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.
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15
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Sidorenko P, Lahav O, Cohen O. Ptychographic ultrahigh-speed imaging. OPTICS EXPRESS 2017; 25:10997-11008. [PMID: 28788786 DOI: 10.1364/oe.25.010997] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We propose and demonstrate numerically a simple method for ultrahigh-speed imaging of complex (amplitude and phase) samples. Our method exploits redundancy in single-shot ptychography (SSP) for reconstruction of multiple frames from a single camera snapshot. We term the method Time-resolved Imaging by Multiplexed Ptychography (TIMP). We demonstrate TIMP numerically-reconstructing 15 frames of a complexed-valued dynamic object from a single noisy camera snapshot. Experimentally, we demonstrate SSP with single pulse illumination with pulse duration of 150 psec, where its spectral bandwidth can support 30 fsec pulses.
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16
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Mulvana H, Browning RJ, Luan Y, de Jong N, Tang MX, Eckersley RJ, Stride E. Characterization of Contrast Agent Microbubbles for Ultrasound Imaging and Therapy Research. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2017; 64:232-251. [PMID: 27810805 DOI: 10.1109/tuffc.2016.2613991] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
The high efficiency with which gas microbubbles can scatter ultrasound compared with the surrounding blood pool or tissues has led to their widespread employment as contrast agents in ultrasound imaging. In recent years, their applications have been extended to include super-resolution imaging and the stimulation of localized bio-effects for therapy. The growing exploitation of contrast agents in ultrasound and in particular these recent developments have amplified the need to characterize and fully understand microbubble behavior. The aim in doing so is to more fully exploit their utility for both diagnostic imaging and potential future therapeutic applications. This paper presents the key characteristics of microbubbles that determine their efficacy in diagnostic and therapeutic applications and the corresponding techniques for their measurement. In each case, we have presented information regarding the methods available and their respective strengths and limitations, with the aim of presenting information relevant to the selection of appropriate characterization methods. First, we examine methods for determining the physical properties of microbubble suspensions and then techniques for acoustic characterization of both suspensions and single microbubbles. The next section covers characterization of microbubbles as therapeutic agents, including as drug carriers for which detailed understanding of their surface characteristics and drug loading capacity is required. Finally, we discuss the attempts that have been made to allow comparison across the methods employed by various groups to characterize and describe their microbubble suspensions and promote wider discussion and comparison of microbubble behavior.
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17
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Black JJ, Yu FTH, Schnatz RG, Chen X, Villanueva FS, Pacella JJ. Effect of Thrombus Composition and Viscosity on Sonoreperfusion Efficacy in a Model of Micro-Vascular Obstruction. ULTRASOUND IN MEDICINE & BIOLOGY 2016; 42:2220-31. [PMID: 27207018 PMCID: PMC4983511 DOI: 10.1016/j.ultrasmedbio.2016.04.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Revised: 03/28/2016] [Accepted: 04/06/2016] [Indexed: 05/11/2023]
Abstract
Distal embolization of micro-thrombi during stenting for myocardial infarction causes micro-vascular obstruction (MVO). We have previously shown that sonoreperfusion (SRP), a microbubble (MB)-mediated ultrasound (US) therapy, resolves MVO from venous micro-thrombi in vitro in saline. However, blood is more viscous than saline, and arterial thrombi that embolize during stenting are mechanically distinct from venous clot. Therefore, we tested the hypothesis that MVO created with arterial micro-thrombi are more resistant to SRP therapy compared with venous micro-thrombi, and higher viscosity further increases the US requirement for effective SRP in an in vitro model of MVO. Lipid MBs suspended in plasma with adjusted viscosity (1.1 cP or 4.0 cP) were passed through tubing bearing a mesh with 40-μm pores to simulate a micro-vascular cross-section; upstream pressure reflected thrombus burden. To simulate MVO, the mesh was occluded with either arterial or venous micro-thrombi to increase upstream pressure to 40 mmHg ± 5 mmHg. Therapeutic long-tone-burst US was delivered to the occluded area for 20 min. MB activity was recorded with a passive cavitation detector. MVO caused by arterial micro-thrombi at either blood or plasma viscosity resulted in less effective SRP therapy compared to venous thrombi. Higher viscosity further reduced the effectiveness of SRP therapy. The passive cavitation detector showed a decrease in inertial cavitation when viscosity was increased, while stable cavitation was affected in a more complex manner. Overall, these data suggest that arterial thrombi may require higher acoustic pressure US than venous thrombi to achieve similar SRP efficacy; increased viscosity decreases SRP efficacy; and both inertial and stable cavitation are implicated in observed SRP efficacy.
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Affiliation(s)
- John J Black
- Center for Ultrasound Molecular Imaging and Therapeutics, University of Pittsburgh Medical Center, Pittsburgh, PA, USA
| | - Francois T H Yu
- Center for Ultrasound Molecular Imaging and Therapeutics, University of Pittsburgh Medical Center, Pittsburgh, PA, USA
| | - Rick G Schnatz
- Center for Ultrasound Molecular Imaging and Therapeutics, University of Pittsburgh Medical Center, Pittsburgh, PA, USA
| | - Xucai Chen
- Center for Ultrasound Molecular Imaging and Therapeutics, University of Pittsburgh Medical Center, Pittsburgh, PA, USA
| | - Flordeliza S Villanueva
- Center for Ultrasound Molecular Imaging and Therapeutics, University of Pittsburgh Medical Center, Pittsburgh, PA, USA
| | - John J Pacella
- Center for Ultrasound Molecular Imaging and Therapeutics, University of Pittsburgh Medical Center, Pittsburgh, PA, USA.
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18
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Abstract
This study presents a unique approach to understanding the biophysical mechanisms of ultrasound-triggered cell membrane disruption (i.e., sonoporation). We report direct correlations between ultrasound-stimulated encapsulated microbubble oscillation physics and the resulting cellular membrane permeability by simultaneous microscopy of these two processes over their intrinsic physical timescales (microseconds for microbubble dynamics and seconds to minutes for local macromolecule uptake and cell membrane reorganization). We show that there exists a microbubble oscillation-induced shear-stress threshold, on the order of kilopascals, beyond which endothelial cellular membrane permeability increases. The shear-stress threshold exhibits an inverse square-root relation to the number of oscillation cycles and an approximately linear dependence on ultrasound frequency from 0.5 to 2 MHz. Further, via real-time 3D confocal microscopy measurements, our data provide evidence that a sonoporation event directly results in the immediate generation of membrane pores through both apical and basal cell membrane layers that reseal along their lateral area (resealing time of ∼<2 min). Finally, we demonstrate the potential for sonoporation to indirectly initiate prolonged, intercellular gaps between adjacent, confluent cells (∼>30-60 min). This real-time microscopic approach has provided insight into both the physical, cavitation-based mechanisms of sonoporation and the biophysical, cell-membrane-based mechanisms by which microbubble acoustic behaviors cause acute and sustained enhancement of cellular and vascular permeability.
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19
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Helfield B, Black JJ, Qin B, Pacella J, Chen X, Villanueva FS. Fluid Viscosity Affects the Fragmentation and Inertial Cavitation Threshold of Lipid-Encapsulated Microbubbles. ULTRASOUND IN MEDICINE & BIOLOGY 2016; 42:782-94. [PMID: 26674676 PMCID: PMC4744112 DOI: 10.1016/j.ultrasmedbio.2015.10.023] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Revised: 10/16/2015] [Accepted: 10/27/2015] [Indexed: 05/04/2023]
Abstract
Ultrasound and microbubble optimization studies for therapeutic applications are often conducted in water/saline, with a fluid viscosity of 1 cP. In an in vivo context, microbubbles are situated in blood, a more viscous fluid (∼4 cP). In this study, ultrahigh-speed microscopy and passive cavitation approaches were employed to investigate the effect of fluid viscosity on microbubble behavior at 1 MHz subject to high pressures (0.25-2 MPa). The propensity for individual microbubble (n = 220) fragmentation was found to significantly decrease in 4-cP fluid compared with 1-cP fluid, despite achieving similar maximum radial excursions. Microbubble populations diluted in 4-cP fluid exhibited decreased wideband emissions (up to 10.2 times), and increasingly distinct harmonic emission peaks (e.g., ultraharmonic) with increasing pressure, compared with those in 1-cP fluid. These results suggest that in vitro studies should consider an evaluation using physiologic viscosity perfusate before transitioning to in vivo evaluations.
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Affiliation(s)
- Brandon Helfield
- Center for Ultrasound Molecular Imaging and Therapeutics, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA
| | - John J Black
- Center for Ultrasound Molecular Imaging and Therapeutics, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA
| | - Bin Qin
- Center for Ultrasound Molecular Imaging and Therapeutics, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA
| | - John Pacella
- Center for Ultrasound Molecular Imaging and Therapeutics, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA
| | - Xucai Chen
- Center for Ultrasound Molecular Imaging and Therapeutics, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA
| | - Flordeliza S Villanueva
- Center for Ultrasound Molecular Imaging and Therapeutics, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA.
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20
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Chen X, Wang J, Pacella JJ, Villanueva FS. Dynamic Behavior of Microbubbles during Long Ultrasound Tone-Burst Excitation: Mechanistic Insights into Ultrasound-Microbubble Mediated Therapeutics Using High-Speed Imaging and Cavitation Detection. ULTRASOUND IN MEDICINE & BIOLOGY 2016; 42:528-538. [PMID: 26603628 PMCID: PMC4698009 DOI: 10.1016/j.ultrasmedbio.2015.09.017] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Revised: 09/11/2015] [Accepted: 09/17/2015] [Indexed: 05/24/2023]
Abstract
Ultrasound (US)-microbubble (MB)-mediated therapies have been found to restore perfusion and enhance drug/gene delivery. On the presumption that MBs do not persist during long US exposure under high acoustic pressures, most schemes use short US pulses when a high US pressure is employed. However, we recently observed an enhanced thrombolytic effect using long US pulses at high acoustic pressures. Therefore, we explored the fate of MBs during long tone-burst exposures (5 ms) at various acoustic pressures and MB concentrations via direct high-speed optical observation and passive cavitation detection. MBs first underwent stable or inertial cavitation depending on the acoustic pressure and then formed gas-filled clusters that continued to oscillate, break up and form new clusters. Cavitation detection confirmed continued, albeit diminishing, acoustic activity throughout the 5-ms US excitation. These data suggest that persisting cavitation activity during long tone bursts may confer additional therapeutic effects.
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Affiliation(s)
- Xucai Chen
- Center for Ultrasound Molecular Imaging and Therapeutics, University of Pittsburgh Medical Center, Pittsburgh, PA 15213, USA
| | - Jianjun Wang
- Center for Ultrasound Molecular Imaging and Therapeutics, University of Pittsburgh Medical Center, Pittsburgh, PA 15213, USA
| | - John J Pacella
- Center for Ultrasound Molecular Imaging and Therapeutics, University of Pittsburgh Medical Center, Pittsburgh, PA 15213, USA
| | - Flordeliza S Villanueva
- Center for Ultrasound Molecular Imaging and Therapeutics, University of Pittsburgh Medical Center, Pittsburgh, PA 15213, USA
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21
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Helfield B, Chen X, Qin B, Villanueva FS. Individual lipid encapsulated microbubble radial oscillations: Effects of fluid viscosity. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2016; 139:204-14. [PMID: 26827018 PMCID: PMC4714991 DOI: 10.1121/1.4939123] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Ultrasound-stimulated microbubble dynamics have been shown to be dependent on intrinsic bubble properties, including size and shell characteristics. The effect of the surrounding environment on microbubble response, however, has been less investigated. In particular, microbubble optimization studies are generally conducted in water/saline, characterized by a 1 cP viscosity, for application in the vasculature (i.e., 4 cP). In this study, ultra-high speed microscopy was employed to investigate fluid viscosity effects on phospholipid encapsulated microbubble oscillations at 1 MHz, using a single, eight-cycle pulse at peak negative pressures of 100 and 250 kPa. Microbubble oscillations were shown to be affected by fluid viscosity in a size- and pressure-dependent manner. In general, the oscillation amplitudes exhibited by microbubbles between 3 and 6 μm in 1 cP fluid were larger than in 4 cP fluid, reaching a maximum of 1.7-fold at 100 kPa for microbubbles 3.8 μm in diameter and 1.35-fold at 250 kPa for microbubbles 4.8 μm in diameter. Simulation results were in broad agreement at 250 kPa, however generally underestimated the effect of fluid viscosity at 100 kPa. This is the first experimental demonstration documenting the effects of surrounding fluid viscosity on microbubble oscillations, resulting in behavior not entirely predicted by current microbubble models.
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Affiliation(s)
- Brandon Helfield
- Center for Ultrasound Molecular Imaging and Therapeutics, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania 15213, USA
| | - Xucai Chen
- Center for Ultrasound Molecular Imaging and Therapeutics, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania 15213, USA
| | - Bin Qin
- Center for Ultrasound Molecular Imaging and Therapeutics, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania 15213, USA
| | - Flordeliza S Villanueva
- Center for Ultrasound Molecular Imaging and Therapeutics, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania 15213, USA
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22
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Drug-Loaded Perfluorocarbon Nanodroplets for Ultrasound-Mediated Drug Delivery. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 880:221-41. [DOI: 10.1007/978-3-319-22536-4_13] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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23
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Raymond JL, Luan Y, van Rooij T, Kooiman K, Huang SL, McPherson DD, Versluis M, de Jong N, Holland CK. Impulse response method for characterization of echogenic liposomes. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2015; 137:1693-703. [PMID: 25920822 PMCID: PMC4417017 DOI: 10.1121/1.4916277] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Revised: 03/04/2015] [Accepted: 03/05/2015] [Indexed: 05/21/2023]
Abstract
An optical characterization method is presented based on the use of the impulse response to characterize the damping imparted by the shell of an air-filled ultrasound contrast agent (UCA). The interfacial shell viscosity was estimated based on the unforced decaying response of individual echogenic liposomes (ELIP) exposed to a broadband acoustic impulse excitation. Radius versus time response was measured optically based on recordings acquired using an ultra-high-speed camera. The method provided an efficient approach that enabled statistical measurements on 106 individual ELIP. A decrease in shell viscosity, from 2.1 × 10(-8) to 2.5 × 10(-9) kg/s, was observed with increasing dilatation rate, from 0.5 × 10(6) to 1 × 10(7) s(-1). This nonlinear behavior has been reported in other studies of lipid-shelled UCAs and is consistent with rheological shear-thinning. The measured shell viscosity for the ELIP formulation used in this study [κs = (2.1 ± 1.0) × 10(-8) kg/s] was in quantitative agreement with previously reported values on a population of ELIP and is consistent with other lipid-shelled UCAs. The acoustic response of ELIP therefore is similar to other lipid-shelled UCAs despite loading with air instead of perfluorocarbon gas. The methods described here can provide an accurate estimate of the shell viscosity and damping for individual UCA microbubbles.
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Affiliation(s)
- Jason L Raymond
- Biomedical Engineering Program, University of Cincinnati, Cardiovascular Center 3940, 231 Albert Sabin Way, Cincinnati, Ohio 45267-0586
| | - Ying Luan
- Department of Biomedical Engineering, Thoraxcenter, Erasmus Medical Center, P.O. Box 2040, 3000 CA, Rotterdam, Netherlands
| | - Tom van Rooij
- Department of Biomedical Engineering, Thoraxcenter, Erasmus Medical Center, P.O. Box 2040, 3000 CA, Rotterdam, Netherlands
| | - Klazina Kooiman
- Department of Biomedical Engineering, Thoraxcenter, Erasmus Medical Center, P.O. Box 2040, 3000 CA, Rotterdam, Netherlands
| | - Shao-Ling Huang
- Department of Internal Medicine, Division of Cardiology, University of Texas Health Science Center, Houston, Texas 77030
| | - David D McPherson
- Department of Internal Medicine, Division of Cardiology, University of Texas Health Science Center, Houston, Texas 77030
| | - Michel Versluis
- Physics of Fluids Group, MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, P.O. Box 217, 7500 AE, Enschede, Netherlands
| | - Nico de Jong
- Department of Biomedical Engineering, Thoraxcenter, Erasmus Medical Center, P.O. Box 2040, 3000 CA, Rotterdam, Netherlands
| | - Christy K Holland
- Department of Internal Medicine, Division of Cardiovascular Health and Disease and Biomedical Engineering Program, University of Cincinnati, Cardiovascular Center 3935, 231 Albert Sabin Way, Cincinnati, Ohio 45267-0586
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Pacella JJ, Brands J, Schnatz FG, Black JJ, Chen X, Villanueva FS. Treatment of microvascular micro-embolization using microbubbles and long-tone-burst ultrasound: an in vivo study. ULTRASOUND IN MEDICINE & BIOLOGY 2015; 41:456-64. [PMID: 25542487 PMCID: PMC4428565 DOI: 10.1016/j.ultrasmedbio.2014.09.033] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Revised: 09/23/2014] [Accepted: 09/30/2014] [Indexed: 05/06/2023]
Abstract
Despite epicardial coronary artery reperfusion by percutaneous coronary intervention, distal micro-embolization into the coronary microcirculation limits myocardial salvage during acute myocardial infarction. Thrombolysis using ultrasound and microbubbles (sonothrombolysis) is an approach that induces microbubble oscillations to cause clot disruption and restore perfusion. We sought to determine whether this technique could restore impaired tissue perfusion caused by thrombotic microvascular obstruction. In 16 rats, an imaging transducer was placed on the biceps femoris muscle, perpendicular to a single-element 1-MHz treatment transducer. Ultrasound contrast perfusion imaging was performed at baseline and after micro-embolization. Therapeutic ultrasound (5000 cycles, pulse repetition frequency = 0.33 Hz, 1.5 MPa) was delivered to nine rats for two 10-min sessions during intra-arterial infusion of lipid-encapsulated microbubbles; seven control rats received no ultrasound-microbubble therapy. Ultrasound contrast perfusion imaging was repeated after each treatment or control period, and microvascular volume was measured as peak video intensity. There was a 90% decrease in video intensity after micro-embolization (from 8.6 ± 4.8 to 0.7 ± 0.8 dB, p < 0.01). The first and second ultrasound-microbubble sessions were respectively followed by video intensity increases of 5.8 ± 5.1 and 8.7 ± 5.7 dB (p < 0.01, compared with micro-embolization). The first and second control sessions, respectively, resulted in no significant increase in video intensity (2.4 ± 2.3 and 3.6 ± 4.9) compared with micro-embolization (0.6 ± 0.7 dB). We have developed an in vivo model that simulates the distal thrombotic microvascular obstruction that occurs after primary percutaneous coronary intervention. Long-pulse-length ultrasound with microbubbles has a therapeutic effect on microvascular perfusion and may be a valuable adjunct to reperfusion therapy for acute myocardial infarction.
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Affiliation(s)
- John J Pacella
- Center for Ultrasound and Molecular Imaging and Therapeutics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.
| | - Judith Brands
- Center for Ultrasound and Molecular Imaging and Therapeutics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Frederick G Schnatz
- Center for Ultrasound and Molecular Imaging and Therapeutics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - John J Black
- Center for Ultrasound and Molecular Imaging and Therapeutics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Xucai Chen
- Center for Ultrasound and Molecular Imaging and Therapeutics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Flordeliza S Villanueva
- Center for Ultrasound and Molecular Imaging and Therapeutics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
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Segers T, de Jong N, Lohse D, Versluis M. Microbubbles for Medical Applications. MICROFLUIDICS FOR MEDICAL APPLICATIONS 2014. [DOI: 10.1039/9781849737593-00081] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Ultrasound contrast agent (UCA) suspensions contain encapsulated microbubbles with radii ranging from 1 to 10 micrometers. The bubbles oscillate to the driving ultrasound pulse generating harmonics of the driving ultrasound frequency. This feature allows for the discrimination of non-linear bubble echoes from linear tissue echoes facilitating the visualization and quantification of blood perfusion in organs. Targeting the microbubbles to specific receptors in the body has led to molecular imaging application with ultrasound and targeted drug delivery with drug-loaded microbubbles. Traditional UCA production methods offer high yield but poor control over the microbubble size and uniformity. Medical ultrasound transducers typically operate at a single frequency, therefore only a small selection of bubbles resonates to the driving ultrasound pulse. Here we discuss recent lab-on-a-chip based production and sorting methods that have been shown to produce highly monodisperse bubbles, thereby improving the sensitivity of contrast-enhanced ultrasound imaging and molecular imaging with microbubbles. Moreover, monodisperse UCA show great potential for targeted drug delivery by the well-controlled bubble response.
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Affiliation(s)
- Tim Segers
- Physics of Fluids Group, MIRA Institute for Biomedical Technology and Technical Medicine, MESA+ Institute for Nanotechnology, University of Twente PO Box 217 7500 AE Enschede The Netherlands
| | - Nico de Jong
- Physics of Fluids Group, MIRA Institute for Biomedical Technology and Technical Medicine, MESA+ Institute for Nanotechnology, University of Twente PO Box 217 7500 AE Enschede The Netherlands
| | - Detlef Lohse
- Physics of Fluids Group, MIRA Institute for Biomedical Technology and Technical Medicine, MESA+ Institute for Nanotechnology, University of Twente PO Box 217 7500 AE Enschede The Netherlands
| | - Michel Versluis
- Physics of Fluids Group, MIRA Institute for Biomedical Technology and Technical Medicine, MESA+ Institute for Nanotechnology, University of Twente PO Box 217 7500 AE Enschede The Netherlands
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Murr PJ, Rauscher MS, Tremmel A, Schardt M, Koch AW. Fluorescence imaging of viscous materials in the ultraviolet-visible wavelength range. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2014; 85:085111. [PMID: 25173316 DOI: 10.1063/1.4892477] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
This paper presents an approach of an innovative measurement principle for the quality control of viscous materials during a manufacturing process based on fluorescence imaging. The main contribution to the state of the art provided by this measurement system is that three equal fluorescence images of a static or moving viscous object are available in different optical paths. The independent images are obtained by two beam splitters which are connected in series. Based on these images, it is possible to evaluate each image separately. In our case, three optical bandpass filters with different center wavelengths of 405 nm, 420 nm, and 440 nm were used to filter the separate fluorescence images. The developed system is useable for the detection of impurities in the micrometer range. Further, incorrect mixing ratios of particular components and wrong single components in the viscous materials can be detected with the setup. Moreover, it is possible to realize static and dynamic measurements. In this case the maximum speed of the objects was 0.2 m/s for the dynamic measurements. Advantages of this measurement setup are the universality due to the use of optical standard components, the small dimension and the opportunity to integrate it easily into ongoing processes. In addition, the measurement system works on a non-contact basis. Thus, the expense for maintenance is at a very low level compared to currently available measurement setups for the investigated application. Furthermore, the setup provides for the first time a simultaneous analysis of more than one component and the detection of impurities concerning their nature and size in a manufacturing process.
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Affiliation(s)
- Patrik J Murr
- Institute for Measurement Systems and Sensor Technology, Technische Universität München, Theresienstraße 90, 80333 München, Germany
| | - Markus S Rauscher
- Institute for Measurement Systems and Sensor Technology, Technische Universität München, Theresienstraße 90, 80333 München, Germany
| | - Anton Tremmel
- Institute for Measurement Systems and Sensor Technology, Technische Universität München, Theresienstraße 90, 80333 München, Germany
| | - Michael Schardt
- Institute for Measurement Systems and Sensor Technology, Technische Universität München, Theresienstraße 90, 80333 München, Germany
| | - Alexander W Koch
- Institute for Measurement Systems and Sensor Technology, Technische Universität München, Theresienstraße 90, 80333 München, Germany
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Kooiman K, Vos HJ, Versluis M, de Jong N. Acoustic behavior of microbubbles and implications for drug delivery. Adv Drug Deliv Rev 2014; 72:28-48. [PMID: 24667643 DOI: 10.1016/j.addr.2014.03.003] [Citation(s) in RCA: 245] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Revised: 02/11/2014] [Accepted: 03/18/2014] [Indexed: 12/21/2022]
Abstract
Ultrasound contrast agents are valuable in diagnostic ultrasound imaging, and they increasingly show potential for drug delivery. This review focuses on the acoustic behavior of flexible-coated microbubbles and rigid-coated microcapsules and their contribution to enhanced drug delivery. Phenomena relevant to drug delivery, such as non-spherical oscillations, shear stress, microstreaming, and jetting will be reviewed from both a theoretical and experimental perspective. Further, the two systems for drug delivery, co-administration and the microbubble as drug carrier system, are reviewed in relation to the microbubble behavior. Finally, future prospects are discussed that need to be addressed for ultrasound contrast agents to move from a pre-clinical tool into a clinical setting.
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28
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Chen X, Leeman JE, Wang J, Pacella JJ, Villanueva FS. New insights into mechanisms of sonothrombolysis using ultra-high-speed imaging. ULTRASOUND IN MEDICINE & BIOLOGY 2014; 40:258-262. [PMID: 24139920 DOI: 10.1016/j.ultrasmedbio.2013.08.021] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Revised: 08/23/2013] [Accepted: 08/28/2013] [Indexed: 06/02/2023]
Abstract
Thrombotic arterial occlusion is the principal etiology for acute cardiovascular syndromes such as stroke, myocardial infarction and unstable angina. Exposing the thrombus to ultrasound and microbubbles facilitates thrombus disruption, making "sonothrombolysis" a potentially powerful therapeutic strategy for thromboembolic diseases. However, optimization of such a strategy, and hence clinical translation, is constrained by an incomplete understanding of mechanisms by which ultrasound-induced microbubble vibrations disrupt blood clots. We posit that previously reported sonothrombolytic efficacy using inertial cavitation regimes was due, at least in part, to mechanical clot disruption by oscillating microbubbles. To test this hypothesis, we optically characterized lipid microbubble interactions with thrombus in the presence of ultrasound using a recently developed ultra-high-speed microscopy imaging system to visualize microbubble acoustic behaviors at megahertz frame rates. A microscope/acoustic stage designed for the system allowed an experimentally created thrombus and microbubbles to be insonified at a co-localized acoustic and optical focus during synchronized high-speed imaging. Under inertial cavitation conditions, large-amplitude microbubble oscillations caused thrombus deformation and pitting. Acoustic radiation forces (Bjerknes forces) further augmented microbubble-thrombus interaction. These observations suggest that a direct mechanical effect of oscillating lipid microbubbles on an adjacent thrombus may play a role in mediating clot disruption in the presence of specific ultrasound conditions.
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Affiliation(s)
- Xucai Chen
- Center for Ultrasound Molecular Imaging and Therapeutics, Heart and Vascular Institute, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA
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