Although in vivo treatment with CD34-TRAIL(+) cells did not lead to tumor growth inhibition, treated mice revealed significantly larger areas of necrosis associated with damage of tumor vasculature than did control mice.
In vivo staining of tumor vasculature with sulfosuccinimidyl-6-(biotinamido) hexanoate-biotin revealed that CD34-TRAIL+ cells but not sTRAIL significantly damaged tumor vasculature, as shown by TdT-mediated dUTP nick end-labeling+ endothelial cells, appearance of hemorrhagic areas, and marked reduction of endothelial area.
The ASPS xenograft tumor vasculature encompassing nests of ASPS cells is highly reactive to antibodies against the endothelial antigen CD34 and is readily accessible to intravenously administered fluorescein isothiocyanate-dextran.
Injection of CD34-TRAIL+ cells resulted in extensive damage of tumor vasculature followed by hemorrhagic necrosis exhibiting a perivascular distribution.