Differential transplantability of tumor-associated stromal cells

At the time of transplantation, tumor fragments contain passenger cells: endothelial cells and other stromal cells from the original host. Here, we investigated the fate of genetically labeled endothelial and nonendothelial stromal cells after transplantation in syngeneic mice. We report that angiogenic stroma associated with tumor or adipose tissue persists when transplanted, remains functional, and governs the initial neovascudarization of grafted tissue fragments for more than 4 weeks after implantation. Surprisingly, the passenger endothelial cells survive longer than other stromal cells, which are replaced by host-activated fibroblasts after 3 weeks. The transplantability of tumor stroma suggests that the anglogenic potential of a tumor xenograft, which determines its viability, depends on the presence of passenger endothelial cells and other stromal cells within the xenograft. These studies of tumor tissue transplantation provide a platform for exploring the role of epithelial-stromal interactions in studies of tumor heterogeneity and drug resistance.