Quantitative Analysis of Cellular Morphology During In Vitro Decidualization

Abstract Decidualization is a differentiation process involving shape reorganization from a fibroblast to an epithelioid‐like appearance characteristic of endometrial stromal cells. For the study of in vitro decidualization, one needs to check that the cells have undergone this process effectively. Verification is usually done by analyzing the expression of decidual markers, but changes in morphology are a more comprehensive feature. However, morphological specificities (i.e., flatness) of endometrial cells prevent the use of existing automated tools. A simple and accurate methodology was developed to quantify the phenotypic changes that occur in an in vitro decidualization system. This approach analyzes cell circularity directly from light microscopy images to follow the effects of progesterone or progestin R5020 in combination with estradiol (E2) and cAMP in inducing the decidualization of human endometrial cells. A statistical model to detect the differences in the kinetics of decidualization of the two hormonal stimuli before all the cell population acquire the decidual phenotype was implemented. It was found that statistical differences in morphology between decidualized and control cells could be detected 2 days after the treatments. Here we detail the model applied, scripts, and input files in order to provide a useful, practical, and low‐cost tool to evaluate morphological aspects of endometrial stromal differentiation. This method allows the verification of the effectiveness of the decidualization process of the stromal endometrial cells without having to use cell replicates, as other methods such as immunofluorescence and RT‐qPCR assays require. Consequently, this approach can follow the kinetics of a living single replicate throughout the experiment. © 2023 Wiley Periodicals LLC. Basic Protocol 1 : Cell circularity quantification of human stromal endometrial cells using ImageJ Basic Protocol 2 : Statistical analysis of cell circularity of human stromal endometrial cells