A color-coded imaging model of the interaction of α_v integrin-GFP expressed in osteosarcoma cells and RFP expressing blood vessels in Gelfoam® vascularized In Vivo

The integrin family of proteins has been shown to be involved in the malignant behavior of cells. We report here development of a color-coded imaging model that can visualize the interaction between α_v integrin linked to green fluorescent protein (GFP) in osteosarcoma cells and blood vessels in Gelfoam® vascularized after implantation in red fluorescent protein (RFP) transgenic nude mice. Human 143B osteosarcoma cells expressing α_v integrin-GFP were generated by transfection with an α_v integrin-GFP vector. Gelfoam® (5×5 mm) was transplanted subcutaneously in transgenic RFP nude mice. The implanted Gelfoam® became highly vascularized with RFP vessels within 14 days. Skin flaps were made at days 7, 14, 21, 28 after transplantation of Gelfoam® for observing vascularization of the Gelfoam® using fluorescence imaging. Gelfoam® is a useful tool to observe angiogenesis in vivo. 143B cells (5×10⁵) expressing α_v integrin-GFP were injected into the Gelfoam® seven days after transplantation of Gelfoam®. Seven days after cancer-cell injection, cancer cells and blood vessels were observed in the Gelfoam® by color-coded confocal microscopy via the skin flap. The 143B cells expressing α_v integrin-GFP proliferated into the Gelfoam®, which contained RFP-expressing blood vessels. Strong expression of α_v integrin-GFP in 143B cells was observed near RFP vessels in the Gelfoam®. The observation of the behavior of α_v integrin-GFP and blood vessels will allow further understanding of the role of α_v integrin in cancer cells.