Characterization of dormant and active human cancer cells by quantitative phase imaging.

The switch of tumor cells from a dormant, non-angiogenic phenotype to an active, angiogenic phenotype is a critical step in early cancer progression. To date, relatively little is known about the cellular behaviors of angiogenic and non-angiogenic tumor cell phenotypes. In this study, holographic imaging cytometry, a quantitative phase imaging (QPI) technique was used to continuously and non-invasively analyze, quantify, and compare a panel of fundamental cellular behaviors of angiogenic and non-angiogenic human osteosarcoma cells (KHOS) in a simple and economical way. Results revealed that angiogenic KHOS cells (KHOS-A) have significantly higher cell motility speeds than their non-angiogenic counterpart (KHOS-N) while no difference in their cell proliferation rates and cell cycle lengths were observed. KHOS-A cells were also found to have significantly smaller cell areas and greater cell optical thicknesses when compared with the non-angiogenic KHOS-N cells. No difference in average cell volumes was observed. These studies demonstrate that the morphology and behavior of angiogenic and non-angiogenic cells can be continuously, efficiently, and non-invasively monitored using a simple, quantitative, and economical system that does not require tedious and time-consuming assays to provide useful information about tumor dormancy.