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postgraduate thesis: Cellular stress induced by microbubble-mediated sonoporation

TitleCellular stress induced by microbubble-mediated sonoporation
Authors
Advisors
Issue Date2013
PublisherThe University of Hong Kong (Pokfulam, Hong Kong)
Citation
Chen, X. []. (2013). Cellular stress induced by microbubble-mediated sonoporation. (Thesis). University of Hong Kong, Pokfulam, Hong Kong SAR. Retrieved from http://dx.doi.org/10.5353/th_b5185938
AbstractSonoporation, referring to transient membrane permeation phenomenon generated by acoustic cavitation, has spurred significant scientific interests for its potential applications in facilitating uptake of drugs and genes into living cells. With an increasing level of technical maturity in realizing sonoporation, scientists are trying to gain a deeper understanding of the cellular responses related to this biophysical phenomenon from the standpoint for drug/gene delivery. However, challenges and difficulties remain to be overcome including providing direct evidences for the microbubble-cell wave matter interaction mechanism, obtaining controllable sonoporation at the desired locations on the cell membrane, maintaining the viability of the sonoporated cells with high efficiency delivery outcomes and so on. Such a lack of scientific foundations has been recognized as a fundamental obstacle in substantiating the application merit of sonoporation. In this study, the overall objective is to stepwise unravel the cellular stress induced by microbubble-mediated sonoporation after resealing. To achieve it, two kinds of well-calibrated ultrasound exposure platforms are designed. One of them can be used for the in situ observation of the wave matter interaction ways during sonoporation via the confocal microscope. The other ultrasound exposure setup can be used for the studies of the sonoporation induced bio-effects which need many cells for analysis. With these designed and well calibrated ultrasound exposure platforms, new insights for the cellular impacts induced by sonoporation are provided. As demonstrated in vitro, sonoporation may inadvertently induce repressive cellular features even whilst enhancing exogenous molecule uptake. Both suspension-type (HL-60) and adherence-type (ZR-75-30) cells were employed in this investigation. They were routinely exposed to 1 MHz pulsed ultrasound with calibrated acoustic field profile and in the presence of microbubbles. The post-exposure morphology and the intracellular actin cytoskeletons dynamics of sonoporated cells were examined in situ using confocal microscopy. Furthermore, the cell-cycle progression kinetics of the viable sonoporated cells were analyzed using flow cytometer. Results show that, for both investigated cell types, viable sonoporated cells would exhibit membrane and nucleus shrinkage, intracellular lipid accumulation and actin deploymerization over a two hours period. On the other hand, as compared to the sham control cells, the deoxyribonucleic acid (DNA) synthesis duration of sonoporated cells is significantly lengthened as indicative of a delay in cell-cycle progression. These features are known to be characteristics of a cellular stress response, suggesting that sonoporation indeed constitutes itself as a cellular stress to living cells even after the cells are resealed. In terms of the implication of this work, this study has shown that sonoporation can be a significant cellular stress both short term and long term after ultrasound exposure. In particular, the intracellular homeostasisis found disrupted even with membrane resealing. Therefore, if sonoporation is to be used for drug delivery, efficiency may be a problem that really needs to be solved in optimizing sonoporation for drug/gene delivery purposes. On the other hand, it raises opportunities for developing other therapeutic applications via sonoporation.
DegreeDoctor of Philosophy
SubjectMicrobubbles
Ultrasonic waves - Therapeutic use
Dept/ProgramElectrical and Electronic Engineering
Persistent Identifierhttp://hdl.handle.net/10722/197120

 

DC FieldValueLanguage
dc.contributor.advisorCheung, PYS-
dc.contributor.advisorYu, ACH-
dc.contributor.authorChen, Xian-
dc.date.accessioned2014-05-07T23:15:28Z-
dc.date.available2014-05-07T23:15:28Z-
dc.date.issued2013-
dc.identifier.citationChen, X. []. (2013). Cellular stress induced by microbubble-mediated sonoporation. (Thesis). University of Hong Kong, Pokfulam, Hong Kong SAR. Retrieved from http://dx.doi.org/10.5353/th_b5185938-
dc.identifier.urihttp://hdl.handle.net/10722/197120-
dc.description.abstractSonoporation, referring to transient membrane permeation phenomenon generated by acoustic cavitation, has spurred significant scientific interests for its potential applications in facilitating uptake of drugs and genes into living cells. With an increasing level of technical maturity in realizing sonoporation, scientists are trying to gain a deeper understanding of the cellular responses related to this biophysical phenomenon from the standpoint for drug/gene delivery. However, challenges and difficulties remain to be overcome including providing direct evidences for the microbubble-cell wave matter interaction mechanism, obtaining controllable sonoporation at the desired locations on the cell membrane, maintaining the viability of the sonoporated cells with high efficiency delivery outcomes and so on. Such a lack of scientific foundations has been recognized as a fundamental obstacle in substantiating the application merit of sonoporation. In this study, the overall objective is to stepwise unravel the cellular stress induced by microbubble-mediated sonoporation after resealing. To achieve it, two kinds of well-calibrated ultrasound exposure platforms are designed. One of them can be used for the in situ observation of the wave matter interaction ways during sonoporation via the confocal microscope. The other ultrasound exposure setup can be used for the studies of the sonoporation induced bio-effects which need many cells for analysis. With these designed and well calibrated ultrasound exposure platforms, new insights for the cellular impacts induced by sonoporation are provided. As demonstrated in vitro, sonoporation may inadvertently induce repressive cellular features even whilst enhancing exogenous molecule uptake. Both suspension-type (HL-60) and adherence-type (ZR-75-30) cells were employed in this investigation. They were routinely exposed to 1 MHz pulsed ultrasound with calibrated acoustic field profile and in the presence of microbubbles. The post-exposure morphology and the intracellular actin cytoskeletons dynamics of sonoporated cells were examined in situ using confocal microscopy. Furthermore, the cell-cycle progression kinetics of the viable sonoporated cells were analyzed using flow cytometer. Results show that, for both investigated cell types, viable sonoporated cells would exhibit membrane and nucleus shrinkage, intracellular lipid accumulation and actin deploymerization over a two hours period. On the other hand, as compared to the sham control cells, the deoxyribonucleic acid (DNA) synthesis duration of sonoporated cells is significantly lengthened as indicative of a delay in cell-cycle progression. These features are known to be characteristics of a cellular stress response, suggesting that sonoporation indeed constitutes itself as a cellular stress to living cells even after the cells are resealed. In terms of the implication of this work, this study has shown that sonoporation can be a significant cellular stress both short term and long term after ultrasound exposure. In particular, the intracellular homeostasisis found disrupted even with membrane resealing. Therefore, if sonoporation is to be used for drug delivery, efficiency may be a problem that really needs to be solved in optimizing sonoporation for drug/gene delivery purposes. On the other hand, it raises opportunities for developing other therapeutic applications via sonoporation.-
dc.languageeng-
dc.publisherThe University of Hong Kong (Pokfulam, Hong Kong)-
dc.relation.ispartofHKU Theses Online (HKUTO)-
dc.rightsCreative Commons: Attribution 3.0 Hong Kong License-
dc.rightsThe author retains all proprietary rights, (such as patent rights) and the right to use in future works.-
dc.subject.lcshMicrobubbles-
dc.subject.lcshUltrasonic waves - Therapeutic use-
dc.titleCellular stress induced by microbubble-mediated sonoporation-
dc.typePG_Thesis-
dc.identifier.hkulb5185938-
dc.description.thesisnameDoctor of Philosophy-
dc.description.thesislevelDoctoral-
dc.description.thesisdisciplineElectrical and Electronic Engineering-
dc.description.naturepublished_or_final_version-
dc.identifier.doi10.5353/th_b5185938-

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