(533i) Long Term Tracking of Cell Lineages with Quantitative Phase Imaging

Cell mass is a biophysical parameter which is useful in monitoring cell growth, cell drug response, and mass partition during cell division. We have developed a method which allows us to continuously track the mass of individual cells in culture for up to 5 generations. The principle of cell mass measurement is quantitative phase imaging (QPI). QPI measures the phase shift of light passing through cells and uses the known relationship between phase shift and cell mass to calculate cell mass. For long term cell mass tracking, we perform cell culture and imaging using an array of microwells, 155 μm square x 40 μm high wells that prevent cells from moving out of the field of view during imaging. We fabricated the microwell array using MY-133, a material with the same refractive index as water, to avoid phase unwrapping during QPI data collection. We design the size of individual microwell to fit it into the field of view of our microscope. During the experiment, the microscope scans through multiple microwells in several minutes, then repeatedly scans the same microwells until the dividing cells cover the entire microwell area. We process the images by using an image processing workflow we developed to remove the microwells and noise from the background. Finally, we segment out each cell in the images, calculate their mass, and generate its profile of mass over time. Mass tracking with 70Z/3 B lymphoblast and MCF-7 breast cancer cells by this method shows it can be used for both non-adherent and adherent cells. Our automated results match the expected cell growth rate and can be used to study cell to cell variation within and across lineages. This method has applications in long-term monitoring of cancer cell drug response as well as the study of B cell fate during differentiation to antibody-secreting plasma cells in response to infectious disease.