Osteosarcoma Cells Enhance Angiogenesis Visualized by Color‐Coded Imaging in the In Vivo Gelfoam® Assay

We previously described a color-coded imaging model that can quantify the length of nascent blood vessels using Gelfoam 1 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 1 angiogenesis assay in ND-GFP mice. Gelfoam 1 was initially transplanted subcutaneously inthe flank oftransgenic ND-GFP nude mice.Seven days aftertransplantationof Gelfoam 1 ,skin flaps were madeand human 143Bosteosarcomacellsexpressinggreen fluorescentprotein(GFP)inthenucleusandred fluorescentprotein(RFP)incytoplasmwereinjected into the transplanted Gelfoam 1 . The control-group mice had only implanted Gelfoam 1 . Skin flaps were made at days 14, 21, and 28 after transplantation of the Gelfoam 1 to allow imaging of vascularization in the Gelfoam 1 using a variable-magnification small animal imaging system and confocal fluorescence microscopy. ND-GFP expressing nascent blood vessels penetrated and spread into the Gelfoam 1 in a time-dependent manner in both control and osteosarcoma-implanted mice. ND-GFP expressing blood vessels in the Gelfoam 1 of the osteosarcoma-implanted mice were associated with the cancer cells and larger and longer than in the Gelfoam 1 -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. J. Cell. Biochem. 115: 1490–1494, 2014. © 2014 Wiley Periodicals, Inc.