Research Article: Membrane-permeabilized sonodynamic therapy enhances drug delivery into macrophages

Date Published: June 10, 2019

Publisher: Public Library of Science

Author(s): Zhengyu Cao, Tianyi Zhang, Xin Sun, Mingyu Liu, Zhaoqian Shen, Bicheng Li, Xuezhu Zhao, Hong Jin, Zhiguo Zhang, Ye Tian, Michael R Hamblin.


Macrophages play a pivotal role in the formation and development of atherosclerosis as a predominant inflammatory cell type present within atherosclerotic plaque. Promoting anti-atherosclerotic drug delivery into macrophages may provide a therapeutic potential on atherosclerotic plaque. In this study, we investigated whether membrane-permeabilized sonodynamic therapy (MP-SDT) enhances drug delivery into THP-1 macrophages. Images of confocal microscopy confirmed that the optimal plasma distribution of the sonosensitizer protoporphyrin IX (PpIX) was at 1 hour incubation. The non-lethal parameter of MP-SDT was determined by cell viability as measured by a CCK-8 assay. Bright field microscopy demonstrated plasma membrane deformation in response to MP-SDT. Using SYTOX Green, a model drug for cellular uptake, we found that MP-SDT significantly induced membrane permeabilization dependent on ultrasound intensity and exposure time. Using Fluo-3 AM, intracellular calcium elevation during MP-SDT was confirmed as a result of membrane permeabilization. Membrane perforation of MP-SDT-treated cells was observed by scanning electron microscopy and transmission electron microscopy. Moreover, MP-SDT-induced membrane permeabilization and perforation were remarkably prevented by scavenging reactive oxygen species (ROS) during MP-SDT. Furthermore, we assessed the therapeutic effect of MP-SDT in combination with anti-atherosclerotic drug atorvastatin. Our results showed that MP-SDT increased the therapeutic effect of atorvastatin on lipid-laden THP-1-derived foam cells, including decreasing lipid droplets, increasing the cholesterol efflux and the expression of PPARγ and ABCG1. In conclusion, MP-SDT might become a promising approach to facilitating the delivery of anti-atherosclerotic drugs into macrophages via membrane permeabilization.

Partial Text

Atherosclerosis is a major contributor to the global burden of cardiovascular events, such as myocardial infarction and stroke [1]. Macrophages, a predominant inflammatory cell type present within atherosclerotic plaque, are critical to the formation and development of atherosclerosis and the progression and rupture of plaque [2]. Anti-atherosclerotic drugs that exert a lipid-efflux effect on macrophages resident in atherosclerotic plaque, like statins, can inhibit atherosclerotic plaque progression [3]. Enhancement of anti-atherosclerotic drug delivery into intraplaque macrophages will greatly promote therapeutic efficiency [4].

In this study, we investigated the effect of non-lethal MP-SDT combining the plasma membrane-located sonosensitizer PpIX and ultrasound at low intensity and short duration. We demonstrated that MP-SDT enhanced drug delivery into macrophages. We also found that MP-SDT-induced plasma membrane permeabilization is associated to ultrasound intensity and exposure time and is dependent on ROS production.