Department of Stem Cell and Regenerative Biotechnology, Konkuk University, Seoul 05029, Korea.
Int J Mol Sci. 2019 Jan 10;20(2):247. doi: 10.3390/ijms20020247.
Graphene and its derivatives are emerging as attractive materials for biomedical applications, including antibacterial, gene delivery, contrast imaging, and anticancer therapy applications. It is of fundamental importance to study the cytotoxicity and biocompatibility of these materials as well as how they interact with the immune system. The present study was conducted to assess the immunotoxicity of graphene oxide (GO) and vanillin-functionalized GO (V-rGO) on THP-1 cells, a human acute monocytic leukemia cell line. The synthesized GO and V-rGO were characterized by using various analytical techniques. Various concentrations of GO and V-rGO showed toxic effects on THP-1 cells such as the loss of cell viability and proliferation in a dose-dependent manner. Cytotoxicity was further demonstrated as an increased level of lactate dehydrogenase (LDH), loss of mitochondrial membrane potential (MMP), decreased level of ATP content, and cell death. Increased levels of reactive oxygen species (ROS) and lipid peroxidation caused redox imbalance in THP-1 cells, leading to increased levels of malondialdehyde (MDA) and decreased levels of anti-oxidants such as glutathione (GSH), glutathione peroxidase (GPX), super oxide dismutase (SOD), and catalase (CAT). Increased generation of ROS and reduced MMP with simultaneous increases in the expression of pro-apoptotic genes and downregulation of anti-apoptotic genes suggest that the mitochondria-mediated pathway is involved in GO and V-rGO-induced apoptosis. Apoptosis was induced consistently with the significant DNA damage caused by increased levels of 8-oxo-dG and upregulation of various key DNA-regulating genes in THP-1 cells, indicating that GO and V-rGO induce cell death through oxidative stress. As a result of these events, GO and V-rGO stimulated the secretion of various cytokines and chemokines, indicating that the graphene materials induced potent inflammatory responses to THP-1 cells. The harshness of V-rGO in all assays tested occurred because of better charge transfer, various carbon to oxygen ratios, and chemical compositions in the rGO. Overall, these findings suggest that it is essential to better understand the parameters governing GO and functionalized GO in immunotoxicity and inflammation. Rational design of safe GO-based formulations for various applications, including nanomedicine, may result in the development of risk management methods for people exposed to graphene and graphene family materials, as these nanoparticles can be used as delivery agents in various biomedical applications.
石墨烯及其衍生物作为生物医学应用的有吸引力的材料而出现，包括抗菌、基因传递、对比成像和抗癌治疗应用。研究这些材料的细胞毒性和生物相容性以及它们与免疫系统的相互作用非常重要。本研究旨在评估氧化石墨烯（GO）和香草醛功能化 GO（V-rGO）对人急性单核细胞白血病细胞系 THP-1 细胞的免疫毒性。通过使用各种分析技术对合成的 GO 和 V-rGO 进行了表征。不同浓度的 GO 和 V-rGO 以剂量依赖性方式表现出对 THP-1 细胞的毒性作用，例如细胞活力和增殖丧失。细胞毒性进一步表现为乳酸脱氢酶（LDH）水平升高、线粒体膜电位（MMP）丧失、ATP 含量降低和细胞死亡。活性氧（ROS）和脂质过氧化水平升高导致 THP-1 细胞的氧化还原失衡，导致丙二醛（MDA）水平升高和谷胱甘肽（GSH）、谷胱甘肽过氧化物酶（GPX）、超氧化物歧化酶（SOD）和过氧化氢酶（CAT）等抗氧化剂水平降低。ROS 生成增加和 MMP 降低同时伴随着促凋亡基因表达增加和抗凋亡基因下调表明，GO 和 V-rGO 诱导的凋亡涉及线粒体介导的途径。与 THP-1 细胞中 8-氧代-dG 水平升高和各种关键 DNA 调节基因上调引起的显著 DNA 损伤一致，诱导凋亡表明 GO 和 V-rGO 通过氧化应激诱导细胞死亡。由于这些事件，GO 和 V-rGO 刺激了各种细胞因子和趋化因子的分泌，表明石墨烯材料对 THP-1 细胞引发了强烈的炎症反应。V-rGO 在所有测试的测定中都具有更强的攻击性，这是由于更好的电荷转移、不同的碳氧比和 rGO 中的化学组成。总体而言，这些发现表明，有必要更好地了解控制 GO 和功能化 GO 在免疫毒性和炎症中的参数。为各种应用（包括纳米医学）设计安全的基于 GO 的配方可能会导致针对暴露于石墨烯和石墨烯家族材料的人群的风险管理方法的发展，因为这些纳米颗粒可用作各种生物医学应用的递送剂。
