Measurement of In vitro Cancer Tumor Hypoxia*

Tumors are characterized as swamps: abnormal and disordered tissue masses with highly stressful conditions of hypoxia, low pH, low nutrient conditions due to a combination of rapid cell growth, lack of vasculature and altered metabolism. While for normal cells that combination would be lethal, for cancer cells it provides a genotoxic environment they are adapted to. We show here using a phosphorescence lifetime imaging (PLIM) technology based oxygen sensor to monitor the local O$_{2}$ level in a extended two dimensional array of cancer cells with strong and mixed gradients to nutrients and O$_{2}$ using a novel pure diffusional three dimensional microfabricated technology the emergence of highly hypotoxic dormant cell metapopulations.