Earth & Biological Sciences Directorate and ‡National Security Directorate, Pacific Northwest National Laboratory , Richland, Washington 99352, United States.
ACS Nano. 2016 Nov 22;10(11):10173-10185. doi: 10.1021/acsnano.6b05452. Epub 2016 Oct 31.
The impact of distinct nanoparticle (NP) properties on cellular response and ultimately human health is unclear. This gap is partially due to experimental difficulties in achieving uniform NP loads in the studied cells, creating heterogeneous populations with some cells "overloaded" while other cells are loaded with few or no NPs. Yet gene expression studies have been conducted in the population as a whole, identifying generic responses, while missing unique responses due to signal averaging across many cells, each carrying different loads. Here, we applied single-cell RNA-Seq to alveolar epithelial cells carrying defined loads of aminated or carboxylated quantum dots (QDs), showing higher or lower toxicity, respectively. Interestingly, cells carrying lower loads responded with multiple strategies, mostly with up-regulated processes, which were nonetheless coherent and unique to each QD type. In contrast, cells carrying higher loads responded more uniformly, with mostly down-regulated processes that were shared across QD types. Strategies unique to aminated QDs showed strong up-regulation of stress responses, coupled in some cases with regulation of cell cycle, protein synthesis, and organelle activities. In contrast, strategies unique to carboxylated QDs showed up-regulation of DNA repair and RNA activities and decreased regulation of cell division, coupled in some cases with up-regulation of stress responses and ATP-related functions. Together, our studies suggest scenarios where higher NP loads lock cells into uniform responses, mostly shutdown of cellular processes, whereas lower loads allow for unique responses to each NP type that are more diversified proactive defenses or repairs of the NP insults.
不同纳米颗粒（NP）特性对细胞反应以及最终对人类健康的影响尚不清楚。造成这种差距的部分原因是，在研究细胞中实现 NP 均匀负载的实验存在困难，导致细胞群体出现异质性，一些细胞“超载”，而其他细胞则负载很少或没有 NP。然而，由于许多细胞之间的信号平均化，基因表达研究已经在整个群体中进行，识别出了通用反应，而错过了由于信号平均化而导致的独特反应，因为每个细胞的负载都不同。在这里，我们应用单细胞 RNA-Seq 对携带不同负载的氨基化或羧基化量子点（QD）的肺泡上皮细胞进行了研究，结果表明，分别具有较高或较低的毒性。有趣的是，携带较低负载的细胞会通过多种策略做出反应，这些策略大多与上调过程相关，但对每种 QD 类型都是一致且独特的。相比之下，携带较高负载的细胞的反应更加一致，大多数下调过程在 QD 类型之间是共享的。氨基化 QD 特有的策略表现出强烈的应激反应上调，在某些情况下与细胞周期、蛋白质合成和细胞器活性的调节相关。相比之下，羧基化 QD 特有的策略表现出 DNA 修复和 RNA 活性的上调，以及细胞分裂调节的减少，在某些情况下与应激反应和与 ATP 相关功能的上调相关。总之，我们的研究表明，较高的 NP 负载会使细胞锁定在一致的反应中，主要是细胞过程的关闭，而较低的负载则允许针对每种 NP 类型的独特反应，这些反应更加多样化，是对 NP 损伤的主动防御或修复。
