Tetrachlorodecaoxide improves the oxygenation status of multicellular tumor spheroids

The benefit of Tetrachlorodecaoxide (TCDO) in improving tumor tissue oxygenation has been tested using multicellular tumor spheroids. Measurements of PO2 values with O2-sensitive microelectrodes revealed a distinct enhancement of the spheroid oxygenation after bolus injection of TCDO into the medium around the spheroid (peak concentration: 0.7 mM). Small spheroids exhibited a uniform, transient rise in PO2 at different locations within the spheroid. Larger spheroids showed a smaller, yet still significant increase in PO2 in inner parts compared to the spheroid periphery. The increase in PO2 after TCDO injection appeared to be less in spheroid areas with low initial PO2 values versus well-oxygenated spheroid regions. Continuous infusion of TCDO for 15 minutes at steady state concentrations in the medium of 33 microM resulted in a substantial and persistent elevation of the local PO2 within spheroids. The PO2 returned to the control level 20 minutes after the stoppage of the infusion.