We previously described a color-coded imaging model that can quantify the length of nascent blood vessels using Gelfoam® implanted in nestin-driven green fluorescent protein (ND-GFP) nude mice. In ND-GFP mice, nascent blood vessels are labeled with GFP. We report here that osteosarcoma cells promote angiogenesis in the Gelfoam® angiogenesis assay in ND-GFP mice. Gelfoam® was initially transplanted subcutaneously in the flank of transgenic ND-GFP nude mice. Seven days after transplantation of Gelfoam®, skin flaps were made and human 143B osteosarcoma cells expressing green fluorescent protein (GFP) in the nucleus and red fluorescent protein (RFP) in cytoplasm were injected into the transplanted Gelfoam®. The control-group mice had only implanted Gelfoam®. Skin flaps were made at days 14, 21, and 28 after transplantation of the Gelfoam® to allow imaging of vascularization in the Gelfoam® using a variable-magnification small animal imaging system and confocal fluorescence microscopy. ND-GFP expressing nascent blood vessels penetrated and spread into the Gelfoam® in a time-dependent manner in both control and osteosarcoma-implanted mice. ND-GFP expressing blood vessels in the Gelfoam® of the osteosarcoma-implanted mice were associated with the cancer cells and larger and longer than in the Gelfoam®-only implanted mice (P < 0.01). The results presented in this report demonstrate strong angiogenesis induction by osteosarcoma cells and suggest this process is a potential therapeutic target for this disease.

The aim of this study is to determine if fluorescence-guided surgery (FGS) can eradicate human fibrosarcoma growing in the retroperitoneum of nude mice. One week after retroperitoneal implantation of human HT1080 fibrosarcoma cells, expressing green fluorescent protein (GFP) (HT-1080-GFP), in nude mice, bright-light surgery (BLS) was performed on all tumor-bearing mice (n = 22). After BLS, mice were randomized into 2 treatment groups; BLS-only (n = 11) or the combination of BLS + FGS (n = 11). The residual tumors remaining after BLS were resected with FGS using a hand-held portable imaging system under fluorescence navigation. The average residual tumor area after BLS + FGS was significantly smaller than after BLS-only (0.4 ± 0.4 mm(2) and 10.5 ± 2.4 mm(2), respectively; p = 0.006). Five weeks after surgery, the fluorescent-tumor areas of BLS- and BLS + FGS-treated mice were 379 ± 147 mm(2) and 11.7 ± 6.9 mm(2), respectively, indicating that FGS greatly inhibited tumor recurrence compared to BLS. The combination of BLS + FGS significantly decreased fibrosarcoma recurrence compared to BLS-only treated mice (p < 0.001). Mice treated with BLS+FGS had a significantly higher disease-free survival rate than mice treated with BLS-only at five weeks after surgery. These results suggest that combination of BLS + FGS significantly reduced the residual fibrosarcoma volume after BLS and improved disease-free survival.