Quantification of three-dimensional dynamics of intercellular geometry under mechanical loading using a weighted directional adaptive-threshold method.

Capturing and quantifying dynamic changes in three-dimensional cellular geometries on fast time scales is a challenge because of mechanical limitations of imaging systems as well as of the inherent tradeoffs between temporal resolution and image quality. We have combined a custom high-speed two-photon microscopy approach with a novel image segmentation method, the weighted directional adaptive-threshold (WDAT), to quantify the dimensions of intercellular spaces of cells under compressive stress on timescales previously inaccessible. The adaptation of a high-speed two-photon microscope addressed the need to capture events occurring on short timescales, while the WDAT method was developed to address artifacts of standard intensity-based analysis methods when applied to this system. Our novel approach is demonstrated by the enhanced temporal analysis of the three-dimensional cellular and extracellular deformations that accompany compressive loading of airway epithelial cells.