Quantitative phase microscopy for time-lapse hypoxia-induced cellular assays based on the transport of intensity equation

Many cellular processes are sensitive to oxygen levels. Therefore, studying how cancer cells respond to oxygen deprivation (hypoxia) can help to understand tumor progression and develop therapies. This study investigates the dynamic response of CAL-27 human oral epithelial carcinoma cells to hypoxic conditions induced by cell culture in a well under a coverslip. A custom-built microscope enables multifocal stack capture every 15 min so continuous monitoring of cellular behavior is possible. Phase analysis, employing the transport of intensity equation (TIE) for phase recovery, is used for time-lapse imaging of local refractive index variance. This variance then serves as an indicator of disorder strength within the cellular environment, providing valuable insights into changes in cellular composition and morphology during hypoxia.