In general the prediction of the toxicity and therapeutic efficacy of engineered nanoparticles in humans is initially determined using in vitro static cell culture assays. However, such test systems may not be sufficient for testing nanoparticles intended for intravenous application. Once injected, these nanoparticles are caught up in the blood stream in vivo and are therefore in continuous movement. Physical forces such as shear stress and cyclic stretch caused by the pulsatile blood flow are known to change the phenotype of endothelial cells which line the luminal side of the vasculature and thus may be able to affect cell-nanoparticle interactions. In this study we investigated the uptake of amorphous silica nanoparticles in primary endothelial cells (HUVEC) cultured under physiological cyclic stretch conditions (1 Hz, 5% stretch) and compared this to cells in a standard static cell culture system. The toxicity of varying concentrations was assessed using cell viability and cytotoxicity studies. Nanoparticles were also characterized for the induction of an inflammatory response. Changes to cell morphology was evaluated in cells by examining actin and PECAM staining patterns and the amounts of nanoparticles taken up under the different culture conditions by evaluation of intracellular fluorescence. The expression profile of 26 stress-related was determined by microarray analysis. The results show that cytotoxicity to endothelial cells caused by silica nanoparticles is not significantly altered under stretch compared to static culture conditions. Nevertheless, cells cultured under stretch internalize fewer nanoparticles. The data indicate that the decrease of nanoparticle content in stretched cells was not due to the induction of cell stress, inflammation processes or an enhanced exocytosis but rather a result of decreased endocytosis. In conclusion, this study shows that while the toxic impact of silica nanoparticles is not altered by stretch this dynamic model demonstrates altered cellular uptake of nanoparticles under physiologically relevant in vitro cell culture models. In particular for the development of nanoparticles for biomedical applications such improved in vitro cell culture models may play a pivotal role in the reduction of animal experiments and development costs.

中文翻译：

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生理循环拉伸下人内皮细胞摄取二氧化硅纳米颗粒的体外研究。


一般来说，工程纳米颗粒对人体的毒性和治疗功效的预测最初是通过体外静态细胞培养测定来确定的。然而，这样的测试系统可能不足以测试用于静脉内应用的纳米颗粒。一旦注射，这些纳米颗粒就会被捕获在体内的血流中，因此会持续运动。众所周知，由脉动血流引起的剪切应力和循环拉伸等物理力会改变排列在脉管系统管腔侧的内皮细胞的表型，因此可能能够影响细胞-纳米颗粒的相互作用。在这项研究中，我们研究了在生理循环拉伸条件（1 Hz，5%拉伸）下培养的原代内皮细胞（HUVEC）中对无定形二氧化硅纳米颗粒的摄取，并将其与标准静态细胞培养系统中的细胞进行比较。使用细胞活力和细胞毒性研究评估不同浓度的毒性。纳米颗粒还具有诱导炎症反应的特征。通过检查肌动蛋白和 PECAM 染色模式来评估细胞形态的变化，并通过评估细胞内荧光来评估不同培养条件下摄取的纳米颗粒的量。通过微阵列分析确定了26个应激相关蛋白的表达谱。结果表明，与静态培养条件相比，二氧化硅纳米粒子对内皮细胞的细胞毒性在拉伸条件下没有显着改变。然而，在拉伸条件下培养的细胞内化的纳米颗粒较少。 数据表明，拉伸细胞中纳米颗粒含量的减少不是由于细胞应激、炎症过程或胞吐作用增强的诱导，而是内吞作用减少的结果。总之，这项研究表明，虽然二氧化硅纳米颗粒的毒性影响不会因拉伸而改变，但该动态模型表明，在生理相关的体外细胞培养模型下，纳米颗粒的细胞摄取发生了变化。特别是对于生物医学应用纳米颗粒的开发，这种改进的体外细胞培养模型可能在减少动物实验和开发成本方面发挥关键作用。