Shanghai Key Laboratory of Orthopedic Implants, Department of Orthopedic Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200011, People's Republic of China.
Key Laboratory of Inorganic Coating Materials, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, People's Republic of China.
Int J Nanomedicine. 2020 Aug 25;15:6355-6372. doi: 10.2147/IJN.S257741. eCollection 2020.
Cerium oxide nanoparticles (CeONPs) are potent scavengers of cellular reactive oxygen species (ROS). Their antioxidant properties make CeONPs promising therapeutic agents for bone diseases and bone tissue engineering. However, the effects of CeONPs on intracellular ROS production in osteoclasts (OCs) are still unclear. Numerous studies have reported that intracellular ROS are essential for osteoclastogenesis. The aim of this study was to explore the effects of CeONPs on osteoclast differentiation and the potential underlying mechanisms.
The bidirectional modulation of osteoclast differentiation by CeONPs was explored by different methods, such as fluorescence microscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), quantitative real-time polymerase chain reaction (qRT-PCR), and Western blotting. The cytotoxic and proapoptotic effects of CeONPs were detected by cell counting kit (CCK-8) assay, TdT-mediated dUTP nick-end labeling (TUNEL) assay, and flow cytometry.
The results of this study demonstrated that although CeONPs were capable of scavenging ROS in acellular environments, they facilitated the production of ROS in the acidic cellular environment during receptor activator of nuclear factor kappa-Β ligand (RANKL)-dependent osteoclast differentiation of bone marrow-derived macrophages (BMMs). CeONPs at lower concentrations (4.0 µg/mL to 8.0 µg/mL) promoted osteoclast formation, as shown by increased expression of and , F-actin ring formation and bone resorption. However, at higher concentrations (greater than 16.0 µg/mL), CeONPs inhibited osteoclast differentiation and promoted apoptosis of BMMs by reducing Bcl2 expression and increasing the expression of cleaved caspase-3, which may be due to the overproduction of ROS.
This study demonstrates that CeONPs facilitate osteoclast formation at lower concentrations while inhibiting osteoclastogenesis in vitro by inducing the apoptosis of BMMs at higher concentrations by modulating cellular ROS levels.
氧化铈纳米粒子（CeONPs）是细胞内活性氧（ROS）的有效清除剂。其抗氧化特性使 CeONPs 成为治疗骨疾病和骨组织工程的有前途的治疗剂。然而，CeONPs 对破骨细胞（OCs）内 ROS 产生的影响尚不清楚。许多研究报告称，细胞内 ROS 对破骨细胞生成至关重要。本研究旨在探讨 CeONPs 对破骨细胞分化的影响及其潜在的机制。
通过荧光显微镜、扫描电子显微镜（SEM）、透射电子显微镜（TEM）、实时定量聚合酶链反应（qRT-PCR）和 Western blot 等不同方法探讨 CeONPs 对破骨细胞分化的双向调节作用。通过细胞计数试剂盒（CCK-8）测定、TdT 介导的 dUTP 缺口末端标记（TUNEL）测定和流式细胞术检测 CeONPs 的细胞毒性和促凋亡作用。
本研究结果表明，尽管 CeONPs 能够在无细胞环境中清除 ROS，但在核因子 kappa-B 配体（RANKL）依赖性破骨细胞分化的骨髓来源巨噬细胞（BMMs）的酸性细胞环境中，CeONPs 促进 ROS 的产生。较低浓度（4.0μg/mL 至 8.0μg/mL）的 CeONPs 促进破骨细胞形成，表现为 和 的表达增加、F-肌动蛋白环形成和骨吸收。然而，在较高浓度（大于 16.0μg/mL）时，CeONPs 通过降低 Bcl2 表达和增加 cleaved caspase-3 的表达，抑制破骨细胞分化并促进 BMMs 凋亡，这可能是由于 ROS 过度产生所致。
本研究表明，CeONPs 在较低浓度下促进破骨细胞形成，而在较高浓度下通过调节细胞内 ROS 水平抑制破骨细胞生成，并诱导 BMMs 凋亡。
