Figure 3.

Tumor necrosis induced by HANSe3 through suppressing MMP-9 is associated with in vivo biodegradation. a) H&E staining of osteosarcoma tissue from mice with treatments for 30 days. Tumor cells are found infringing into adjacent muscular layer in control and HANSe10 group. The tumor tissue in HANSe3 group is separated into minor tumors by fibrous tissues, exhibiting a necrosis phenotype. b) Von Kossa staining of osteosarcoma tissue indicates the presence of residual materials. HAN is not degraded and the particles aggregate to form granules that are encapsulated by fibrous tissues. The negative staining for HANSe3 group indicates that HANSe3 nanoparticles have been completely degraded. The expressions of Ki-67 (a maker protein for malignant proliferation), and MMP-9 (a metalloproteinase responsible for extracellular matrix degradation and tumor invasion) were evaluated by immunohistochemical staining (c–d). There is no difference for Ki-67 expression between groups (c), indicating that tumor cell proliferation is not effected by HANSe. d) HANSe3 significantly decreased MMP-9 expression, suggesting that HANSe3 may inhibit osteosarcoma by suppressing tumor invasion instead of cell proliferation.