Quantification of Changes in Salivary Gland Morphology Using Cell Graphs

Branching morphogenesis is a developmental process shared by many organs, including the submandibular salivary gland. During morphogenesis, cells within the gland proliferate and undergo rearrangements and shape changes to result in alterations to the global tissue morphology. However, an integrated understanding of how cellular changes result in branching morphogenesis does not exist. Objectives: We used a mathematical tool, referred to as cell graphs, to quantify changes in cell patterns obtained from confocal images as a first step in generating a mathematical model to describe branching morphogenesis. Methods: Salivary gland organ cultures were treated with pharmacological inhibitors targeting Rho kinase (ROCK), which halts progression of clefts in the surface of the epithelium to inhibit the normal process of branching morphogenesis. We captured confocal images of developing salivary gland organ cultures immunostained with a nuclear marker and an epithelial marker. From confocal images, we performed image segmentation to define epithelial and mesenchymal nuclei, and applied cell graphs to these segmented images. Results: Cell graphs identified quantitative mathematical features characteristic of epithelial vs mesenchymal cells and also distinguished between glands treated with ROCK inhibitors vs vehicle control-treated glands. Conclusions: Quantitative cell graph features are being used with other methods to create a mathematical model that will both describe and be predictive of the developing salivary gland. The mathematical model will provide integrated insights into cellular and physical processes driving morphogenesis at a systems level. Supported by NIDCR RO1DE01924402 and the University at Albany, SUNY