TY - JOUR
T1 - Viability of endothelial cells after ultrasound-mediated sonoporation
T2 - Influence of targeting, oscillation, and displacement of microbubbles
AU - van Rooij, Tom
AU - Skachkov, Ilya
AU - Beekers, Inés
AU - Lattwein, Kirby R.
AU - Voorneveld, Jason D.
AU - Kokhuis, Tom J A
AU - Bera, Deep
AU - Luan, Ying
AU - van der Steen, Antonius F W
AU - de Jong, Nico
AU - Kooiman, Klazina
PY - 2016
Y1 - 2016
N2 - Microbubbles (MBs) have been shown to create transient or lethal pores in cell membranes under the influence of ultrasound, known as ultrasound-mediated sonoporation. Several studies have reported enhanced drug delivery or local cell death induced by MBs that are either targeted to a specific biomarker (targeted microbubbles, tMBs) or that are not targeted (non-targeted microbubbles, ntMBs). However, both the exact mechanism and the optimal acoustic settings for sonoporation are still unknown. In this study we used real-time uptake patterns of propidium iodide, a fluorescent cell impermeable model drug, as a measure for sonoporation. Combined with high-speed optical recordings of MB displacement and ultra-high-speed recordings of MB oscillation, we aimed to identify differences in MB behavior responsible for either viable sonoporation or cell death. We compared ntMBs and tMBs with identical shell compositions exposed to long acoustic pulses (500–50,000 cycles) at various pressures (150–500 kPa). Propidium iodide uptake highly correlated with cell viability; when the fluorescence intensity still increased 120 s after opening of the pore, this resulted in cell death. Higher acoustic pressures and longer cycles resulted in more displacing MBs and enhanced sonoporation. Non-displacing MBs were found to be the main contributor to cell death, while displacement of tMBs enhanced reversible sonoporation and preserved cell viability. Consequently, each therapeutic application requires different settings: non-displacing ntMBs or tMBs are advantageous for therapies requiring cell death, especially at 500 kPa and 50,000 cycles, whereas short acoustic pulses causing limited displacement should be used for drug delivery.
AB - Microbubbles (MBs) have been shown to create transient or lethal pores in cell membranes under the influence of ultrasound, known as ultrasound-mediated sonoporation. Several studies have reported enhanced drug delivery or local cell death induced by MBs that are either targeted to a specific biomarker (targeted microbubbles, tMBs) or that are not targeted (non-targeted microbubbles, ntMBs). However, both the exact mechanism and the optimal acoustic settings for sonoporation are still unknown. In this study we used real-time uptake patterns of propidium iodide, a fluorescent cell impermeable model drug, as a measure for sonoporation. Combined with high-speed optical recordings of MB displacement and ultra-high-speed recordings of MB oscillation, we aimed to identify differences in MB behavior responsible for either viable sonoporation or cell death. We compared ntMBs and tMBs with identical shell compositions exposed to long acoustic pulses (500–50,000 cycles) at various pressures (150–500 kPa). Propidium iodide uptake highly correlated with cell viability; when the fluorescence intensity still increased 120 s after opening of the pore, this resulted in cell death. Higher acoustic pressures and longer cycles resulted in more displacing MBs and enhanced sonoporation. Non-displacing MBs were found to be the main contributor to cell death, while displacement of tMBs enhanced reversible sonoporation and preserved cell viability. Consequently, each therapeutic application requires different settings: non-displacing ntMBs or tMBs are advantageous for therapies requiring cell death, especially at 500 kPa and 50,000 cycles, whereas short acoustic pulses causing limited displacement should be used for drug delivery.
KW - Drug delivery
KW - Endothelial cells
KW - Microbubble behavior
KW - Sonoporation
KW - Therapy
KW - Ultrasound contrast agents
UR - http://www.scopus.com/inward/record.url?scp=84980410138&partnerID=8YFLogxK
U2 - 10.1016/j.jconrel.2016.07.037
DO - 10.1016/j.jconrel.2016.07.037
M3 - Article
AN - SCOPUS:84980410138
SN - 0168-3659
VL - 238
SP - 197
EP - 211
JO - Journal of Controlled Release
JF - Journal of Controlled Release
ER -