Ding Fengan, Li Yiping, Liu Jing, Liu Lei, Yu Wenmin, Wang Zhi, Ni Haifeng, Liu Bicheng, Chen Pingsheng
School of Medicine, Southeast University, Nanjing, People's Republic of China.
Institute of Nephrology, The Affiliated Zhongda Hospital, Southeast University, Nanjing, People's Republic of China.
Int J Nanomedicine. 2014 Sep 12;9:4317-30. doi: 10.2147/IJN.S68685. eCollection 2014.
Gold nanoparticles (GNPs) can potentially be used in biomedical fields ranging from therapeutics to diagnostics, and their use will result in increased human exposure. Many studies have demonstrated that GNPs can be deposited in the kidneys, particularly in renal tubular epithelial cells. Chronic hypoxic is inevitable in chronic kidney diseases, and it results in renal tubular epithelial cells that are susceptible to different types of injuries. However, the understanding of the interactions between GNPs and hypoxic renal tubular epithelial cells is still rudimentary. In the present study, we characterized the cytotoxic effects of GNPs in hypoxic renal tubular epithelial cells.
Both 5 nm and 13 nm GNPs were synthesized and characterized using various biophysical methods, including transmission electron microscopy, dynamic light scattering, and ultraviolet-visible spectrophotometry. We detected the cytotoxicity of 5 and 13 nm GNPs (0, 1, 25, and 50 nM) to human renal proximal tubular cells (HK-2) by Cell Counting Kit-8 assay and lactate dehydrogenase release assay, but we just found the toxic effect in the 5 nm GNP-treated cells at 50 nM dose under hypoxic condition. Furthermore, the transmission electron microscopy images revealed that GNPs were either localized in vesicles or free in the lysosomes in 5 nm GNPs-treated HK-2 cells, and the cellular uptake of the GNPs in the hypoxic cells was significantly higher than that in normoxic cells. In normoxic HK-2 cells, 5 nm GNPs (50 nM) treatment could cause autophagy and cell survival. However, in hypoxic conditions, the GNP exposure at the same condition led to the production of reactive oxygen species, the loss of mitochondrial membrane potential (ΔΨM), and an increase in apoptosis and autophagic cell death.
CONCLUSION/SIGNIFICANCE: Our results demonstrate that renal tubular epithelial cells presented different responses under normoxic and hypoxic environments, which provide an important basis for understanding the risks associated with GNP use-especially for the potential GNP-related therapies in chronic kidney disease patients.
金纳米颗粒（GNPs）在从治疗到诊断的生物医学领域具有潜在应用价值，其使用会导致人类暴露增加。许多研究表明，GNPs可沉积在肾脏中，尤其是肾小管上皮细胞。慢性肾脏病中慢性缺氧不可避免，这会导致肾小管上皮细胞易受不同类型损伤。然而，对于GNPs与缺氧肾小管上皮细胞之间相互作用的理解仍很初步。在本研究中，我们对GNPs在缺氧肾小管上皮细胞中的细胞毒性作用进行了表征。
合成了5纳米和13纳米的GNPs，并使用包括透射电子显微镜、动态光散射和紫外可见分光光度法在内的各种生物物理方法对其进行了表征。我们通过细胞计数试剂盒-8法和乳酸脱氢酶释放法检测了5纳米和13纳米GNPs（0、1、25和50纳摩尔）对人肾近端小管细胞（HK-2）的细胞毒性，但仅在缺氧条件下50纳摩尔剂量的5纳米GNP处理细胞中发现了毒性作用。此外，透射电子显微镜图像显示，5纳米GNPs处理的HK-2细胞中，GNPs要么定位在囊泡中，要么游离于溶酶体中，缺氧细胞对GNPs的细胞摄取明显高于常氧细胞。在常氧HK-2细胞中，5纳米GNPs（50纳摩尔）处理可导致自噬和细胞存活。然而，在缺氧条件下，相同条件下的GNP暴露会导致活性氧产生、线粒体膜电位（ΔΨM）丧失以及凋亡和自噬性细胞死亡增加。
结论/意义：我们的结果表明，肾小管上皮细胞在常氧和缺氧环境下呈现不同反应，这为理解与GNP使用相关的风险提供了重要依据——尤其是对于慢性肾脏病患者潜在的GNP相关治疗。
