Longitudinal investigation of prostate tumor spheroid proliferation with dynamic line-field optical coherence tomography

Recently, it has become widely recognized that culturing cancer cells <i>in vitro</i> in small, 3D aggregates known as tumor spheroids provides a more physiologically relevant model of <i>in vivo</i> tumor behavior compared to 2D monolayer cultures. Dynamic optical coherence tomography (dOCT) is a non-invasive imaging modality that, by analyzing temporal fluctuations in the light scattered from biological tissue, does not require exogenous contrast agents to visualize and quantify cellular activity within 3D cell cultures. However, recent volumetric dOCT studies have encountered challenges due to low acquisition speeds. In this study, we present morphological and dynamic analyses of prostate tumor spheroid growth over a two-week longitudinal period, utilizing a line-field dOCT platform. Volumetric dOCT data were acquired for each spheroid in 16 seconds. Our method clearly differentiated between active cellular metabolism in live spheroids and the lack of activity in spheroids fixed with formaldehyde. Quantitative validation of the dynamic signal was conducted using the Alamar Blue proliferation assay, while qualitative validation was provided by live/dead fluorescence microscopy.