Department of Physics, Concordia University, 7141 Sherbrooke St. W, H4B 1R6 Montreal, Canada.
Department of Biology, Concordia University, 7141 Sherbrooke St. W, H4B 1R6 Montreal, Canada.
J Control Release. 2023 Jun;358:333-344. doi: 10.1016/j.jconrel.2023.05.004. Epub 2023 May 10.
The local fluid dynamics experienced by circulating microbubbles vary across different anatomical sites, which can influence ultrasound-mediated therapeutic delivery efficacy. This study aimed to elucidate the effect of fluid flow rate in combination with repeated short-pulse ultrasound on microbubble-mediated endothelial cell permeabilization. Here, a seeded monolayer of human umbilical (HUVEC) or brain endothelial cells (HBEC-5i) was co-perfused with a solution of microbubbles and propidium iodide (PI) at either a flow rate of 5 or 30 ml/min. Using an acoustically coupled inverted microscope, cells were exposed to 1 MHz ultrasound with 20-cycle bursts, 1 ms PRI, and 2 s duration at a peak negative pressure of 305 kPa to assess the role of flow rate on ultrasound-stimulated endothelial cell permeability, as well as Ca modulation. In addition, the effect of inter-pulse delays (∆t = 1s) on the resulting endothelial permeability was investigated. Our results demonstrate that under an identical acoustic stimulus, fast-flowing microbubbles resulted in a statistically significant increase in cell membrane permeability, at least by 2.3-fold, for both endothelial cells. Likewise, there was a substantial difference in intracellular Ca levels between the two examined flow rates. In addition, multiple short pulses rather than a single pulse ultrasound, with an equal number of bursts, significantly elevated endothelial cell permeabilization, at least by 1.4-fold, in response to ultrasound-stimulated microbubbles. This study provides insights into the design of optimal, application-dependent pulsing schemes to improve the effectiveness of ultrasound-mediated local therapeutic delivery.
循环微泡在不同解剖部位所经历的局部流动力学变化会影响超声介导的治疗输送效果。本研究旨在阐明流体流速与重复短脉冲超声联合作用对微泡介导的内皮细胞通透性的影响。在此，将人脐静脉（HUVEC）或脑内皮细胞（HBEC-5i）的种单层与微泡和碘化丙啶（PI）溶液一起以 5 或 30 ml/min 的流速共灌注。使用声学耦合倒置显微镜，将细胞暴露于 1 MHz 超声，20 个周期的脉冲，1 ms 的 PRI 和 2 s 的持续时间，峰值负压为 305 kPa，以评估流速对超声刺激内皮细胞通透性以及钙调节的作用。此外，还研究了脉冲间延迟（∆t=1s）对内皮通透性的影响。我们的结果表明，在相同的声刺激下，对于两种内皮细胞，快速流动的微泡导致细胞膜通透性显著增加，至少增加了 2.3 倍。同样，两种检查流速之间的细胞内 Ca 水平存在显著差异。此外，与单个脉冲超声相比，多个短脉冲（具有相同数量的脉冲）显著提高了内皮细胞通透性，至少增加了 1.4 倍，这是对超声刺激微泡的反应。本研究为设计最佳的、依赖于应用的脉冲方案提供了深入的了解，以提高超声介导的局部治疗输送的效果。
