International Journal of Nanomedicine (Aug 2020)
Cerium Oxide Nanoparticles Regulate Osteoclast Differentiation Bidirectionally by Modulating the Cellular Production of Reactive Oxygen Species
Abstract
Kai Yuan,1,* Jingtian Mei,1,* Dandan Shao,2 Feng Zhou,1 Han Qiao,1 Yakun Liang,3 Kai Li,2 Tingting Tang1 1Shanghai 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; 2Key Laboratory of Inorganic Coating Materials, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, People’s Republic of China; 3Shanghai Institute of Precision Medicine, Shanghai 200125, People’s Republic of China*These authors contributed equally to this workCorrespondence: Tingting TangShanghai Key Laboratory of Orthopedic Implants, Department of Orthopedic Surgery,Shanghai Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Room 701, No. 3 Building, 639 Zhizaoju Road, Shanghai 200011, People’s Republic of ChinaTel/Fax +86 21 6313 7020Email [email protected] LiKey Laboratory of Inorganic Coating Materials, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai 200050, People’s Republic of ChinaTel/Fax +86 21-52413903Email [email protected]: Cerium oxide nanoparticles (CeO2NPs) are potent scavengers of cellular reactive oxygen species (ROS). Their antioxidant properties make CeO2NPs promising therapeutic agents for bone diseases and bone tissue engineering. However, the effects of CeO2NPs 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 CeO2NPs on osteoclast differentiation and the potential underlying mechanisms.Methods: The bidirectional modulation of osteoclast differentiation by CeO2NPs 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 CeO2NPs were detected by cell counting kit (CCK-8) assay, TdT-mediated dUTP nick-end labeling (TUNEL) assay, and flow cytometry.Results: The results of this study demonstrated that although CeO2NPs 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-&Bgr; ligand (RANKL)-dependent osteoclast differentiation of bone marrow-derived macrophages (BMMs). CeO2NPs at lower concentrations (4.0 μg/mL to 8.0 μg/mL) promoted osteoclast formation, as shown by increased expression of Nfatc1 and C-Fos, F-actin ring formation and bone resorption. However, at higher concentrations (greater than 16.0 μg/mL), CeO2NPs 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.Conclusion: This study demonstrates that CeO2NPs 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.Keywords: cerium oxide nanoparticles, osteoclast, osteoclastogenesis, ROS, apoptosis
