Influence of synthetic superparamagnetic iron oxide on dendritic cells

Yongbin Mou1, Baoan Chen2, Yu Zhang3, Yayi Hou4, Hao Xie4, Guohua Xia2, Meng Tang5, Xiaofeng Huang1, Yanhong Ni1, Qingang Hu1,6 1Central Laboratory of Stomatology, Stomatological Hospital Affiliated Medical School, Nanjing University, 2Department of Hematology, Zhongda Hospital, Medical School, Southeast University, 3State Key Laboratory of Bioelectronics, Jiangsu Key Laboratory for Biomaterials and Devices, Southeast University, 4Immunology and Reproductive Biology Laboratory, Medical School, Nanjing University, 5Laboratory of Environmental Medicine and Engineering, Ministry of Education, School of Public Health, Southeast University, Nanjing, People's Republic of China; 6Leeds Dental Institute, Faculty of Medicine and Health, University of Leeds, Leeds, UK Background: This study investigated the influence of synthetic superparamagnetic iron oxide (SPIO) on dendritic cells and provides a possible method for labeling these cells. Methods: SPIO nanoparticles were prepared, and their morphology and magnetic properties were characterized. The particles were endocytosed by dendritic cells generated from mouse bone marrow. Labeling efficiency and cellular uptake were analyzed by Prussian blue staining and quantitative spectrophotometric assay. Meanwhile, the surface molecules, cellular apoptosis, and functional properties of the SPIO-labeled dendritic cells were explored by flow cytometry and the mixed lymphocyte reaction assay. Results: The synthetic nanoparticles possessed a spherical shape and good superparamagnetic behavior. The mean concentration of iron in immature and mature dendritic cells was 31.8 ± 0.7 µg and 35.6 ± 1.0 µg per 1 × 106 cells, respectively. After 12 hours of incubation with SPIO at a concentration of 25 µg/mL, nearly all cells were shown to contain iron. Interestingly, cellular apoptosis and surface expression of CD80, CD86, major histocompatibility II, and chemokine receptor 7 in mature dendritic cells were not affected to any significant extent by SPIO labeling. T cell activation was maintained at a low ratio of dendritic cells to T cells. Conclusion: SPIO nanoparticles have good superparamagnetic behavior, highly biocompatible characteristics, and are suitable for use in further study of the migratory behavior and biodistribution of dendritic cells in vivo. Keywords: superparamagnetic iron oxide, dendritic cell, cell labeling