ABSTRACT
Objective·To investigate the effect of gold nanoparticles (AuNPs) on exosome secretion of mesenchymal stem cells (MSCs) via blocking autophagy flux.Methods·Rat derived MSCs were treated with AuNPs (0,15,30,90,150 μg/mL),and the cell proliferation was detected with CCK-8 assay to evaluate the cytotoxicity of AuNPs.Then,MSCs were divided into normal control group,AuNPs group (20 μg/mL AuNPs for 72 h) and positive control group (5 μmol/L chloroquine for 4 h).Transmission electron microscopy was used to observe the ultrastructure of MSCs,and exosomes were extracted by ultracentrifugation and tested with nanoparticle analyzer and scan electron microscopy.The autophagy was observed by confocal microscopy and verified by Western blotting.Results·Low concentrations of AuNPs (0 to 30 μg/mL) slightly affected the cell proliferation.MSCs of AuNPs group secreted more abundant and smaller exosomes than those of control group,and expressed significantly more LC3 and p62 (both P＜0.05).Autophagosomes in AuNPs group were increased and fusion of lysosomes and autophagosomes was blocked.Conclusion·AuNPs block the autophagy flux and regulates the secretion of exosomes.