E-selectin targeting to visualize tumors in vivo

Generally angiogenic factors induce the expression of E-selectin in vascular endothelial cells in the tumors. In this study, we employed an anti-E-selectin monoclonal antibody to target tumors in vivo and evaluated an optical imaging reagent to visualize tumor regions. The anti-E-selectin antibody was conjugated on the surface of liposomes, which encapsulated the near-infrared fluorescent substances Cy3 or Cy5.5. The liposomes efficiently recognized human umbilical vein endothelial cells only when E-selectin was induced by angiogenic factors such as TNF-alpha in vitro. Cy5.5 encapsulated into liposomes that were conjugated with an anti-E-selectin antibody successfully visualized Ehrlich ascites tumor cells when transplanted into mice. Thus, E-selectin targeting with liposomes containing a near-infrared fluorescent dye was found effective in visualizing tumors in vivo. This strategy should be extremely useful as a method to identify sentinel lymphatic nodes and angiogenic tumors as well as use for drug delivery to tumor cells.