[Morphological changes in osteosarcoma xenografts in nude mice after inhibiting angiogenesis by Ad-VEGF-siRNA].

Background And Objective: Vascular endothelial growth factor (VEGF) is a critical stimulator for angiogenesis of osteosarcoma. This study was to investigate the morphological changes in osteosarcoma xenografts in nude mice after inhibiting angiogenesis by Ad-VEGF-siRNA.

Methods: The animal model of osteosarcoma xenografts was constructed by subcutaneous inoculation of osteosarcoma MG63 cells into nude mice. The mice were randomly divided into three groups, 15 mice in each group: group A and control groups B and C. The tumor nodules were injected with Ad-VEGF-siRNA in group A, an equal dose of Ad-EGFP and PBS, respectively, in groups B and C. The volume and weight of tumors were measured every two days after injection and the growth curves were drawn. The tumor samples were observed and analyzed using HE staining. Angiogenesis was assessed by immunohistochemical staining using anti-VEGF and CD31 antibodies. The ultrastructure of vasculogenic mimicry (VM) was observed using transmission electron microscopy (TEM).

Results: The mean volume, weight, microvessel density (MVD) and VEGF expression of tumors in Ad-VEGF-siRNA-treated group were significantly lower than those in the control groups. MVD was positively correlated to VEGF expression, with a correlation coefficient of 0.9989. The number of VM was 1.40+/-0.55 in the Ad-VEGF-siRNA group, which was significantly less than those in the two control groups.

Conclusion: Ad-VEGF-siRNA could effectively block angiogenesis in osteosarcoma xenografts in nude mice.