Figure 6

Mitochondrial damage and autophagic activity triggered by SiNPs. (A) Untreated cells. (B) Typical autophagic vacuoles with partially degraded cytoplasmic materials and electron-dense SiNPs. The whole process of SiNPs-mediated autophagy in HUVECs as follow: (C) Electron-dense SiNPs (black arrow) were internalized into cells via endocytic pathways; (D) SiNPs (black arrow) dispersed in cytoplasm either free or as membrane-bound aggregates in lysosomes, accompanyied with swollen mitochondria (asterisk); (E) Autolysosomes with double-layered membranes contained cellular debris, some of them contained mitochondria (white arrow) or electron-dense SiNPs (black arrow) were undergoing degradation at different stages; (F) an obviously larger autophagic vacuole was formed after vesicle fusion containing mitochondria (white arrow) and electron-dense SiNPs (black arrow).