Department of Physiology and Pharmacology, Chang Gung University, Taoyuan, 33302, Taiwan, Republic of China.
Institute of Biomedical Sciences, Chang Gung University, Taoyuan, 33302, Taiwan, Republic of China.
Int J Nanomedicine. 2022 Mar 5;17:969-981. doi: 10.2147/IJN.S337942. eCollection 2022.
Intravascular delivery of nanoparticles for theranostic application permits direct interaction of nanoparticles and vascular cells. Since vascular smooth muscle cells (VSMCs), the major components of the vascular wall, are constantly subjected to mechanical stimulation from hemodynamic influence, we asked whether cyclic strain may modulate internalization of magnetic nanoparticles (MNPs) by cultured VSMCs.
Cyclic strain (1 Hz and 10%) was applied with Flexcell system in cultured VSMCs from rats, with cell-associated MNPs (MNP) determined by a colorimetric iron assay. Transmission and scanning electron microscopy were used for morphology studies. Confocal microscopy was used to demonstrate distribution of actin assembly in VSMCs.
Incubation of poly(acrylic acid) (PAA)-coated MNPs with VSMCs for 4 h induced microvilli formation and MNP internalization. Application of cyclic strain for 4-12 h significantly reduced MNP by up to 65% ( < 0.05), which was associated with blunted microvilli and reduced vesicle size/cell, but not vesicle numbers/cell. Confocal microscopy demonstrated that both cyclic strain and fibronectin coating of the culture plate reduced internalized MNPs, which were co-localized with vinculin. Furthermore, cytochalasin D reduced MNP, suggesting a role of actin polymerization in MNP uptake by VSMCs; however, a myosin II ATPase inhibitor, blebbistatin, exhibited no effect. Cyclic strain also attenuated uptake of PAA-MNPs by LN-229 cells and uptake of poly-L-lysine-coated MNPs by VSMCs.
In such a dynamic milieu, cyclic strain may impede cellular internalization of nanocarriers, which spares the nanocarriers and augments their delivery to the target site in the lumen of vessels or outside of the circulatory system.
用于治疗诊断应用的血管内递纳米粒子允许纳米粒子与血管细胞直接相互作用。由于血管平滑肌细胞（VSMCs）是血管壁的主要组成部分，它们会不断受到血流动力学影响的机械刺激，因此我们想知道周期性应变是否会调节培养的 VSMCs 对磁性纳米粒子（MNP）的内化。
使用 Flexcell 系统在大鼠培养的 VSMCs 中施加周期性应变（1 Hz 和 10%），通过比色铁测定法测定细胞相关的 MNPs（MNP）。使用透射电子显微镜和扫描电子显微镜进行形态学研究。使用共聚焦显微镜来证明 VSMCs 中肌动蛋白组装的分布。
用 PAA 包裹的 MNPs 与 VSMCs 孵育 4 小时会诱导微绒毛形成和 MNP 内化。应用周期性应变 4-12 小时会使 MNP 减少多达 65%（<0.05），这与微绒毛变钝和囊泡大小/细胞减少有关，但与囊泡数量/细胞无关。共聚焦显微镜显示，周期性应变和纤维连接蛋白包被培养板都减少了内化的 MNPs，这些 MNPs与 vinculin 共定位。此外，细胞松弛素 D 减少了 MNP，表明肌动蛋白聚合在 VSMCs 摄取 MNP 中起作用；然而，肌球蛋白 II ATP 酶抑制剂 blebbistatin 没有效果。周期性应变也会减弱 LN-229 细胞对 PAA-MNP 的摄取以及 VSMCs 对多聚-L-赖氨酸包裹的 MNPs 的摄取。
在这种动态环境中，周期性应变可能会阻碍纳米载体的细胞内化，从而保护纳米载体并增加它们在血管内腔或循环系统外的靶部位的递呈。
