Collagen-Embedded Tumor Transplantations in Tadpoles.

The tadpole provides a valuable model for studying tumorigenesis and tumor immunity by intravital real-time microscopy. Using well-characterized thymic lymphoid tumor lines (15/0 and ff-2) that are transplantable into their compatible hosts (LG-15 isogenic clones and the F inbred strain, respectively), a system of semisolid tumor engraftment has been designed. Because these lymphoid tumor cell lines are not adherent and grow in suspension, they are first immobilized in a matrix of type I rat tail collagen before transplantation as a semisolid tumor graft under the transparent dorsal skin in the head region of a tadpole. This semisolid tumor engraftment is amenable to manipulation and permits real-time visualization of tumor growth, neovascularization, collagen rearrangements, immune cell infiltration, and formation of the tumor microenvironment.