Fibrotic substrate stiffness enhances endometriotic epithelial cell motility.

Fibrosis is a common pathological feature of inflammatory conditions across various organ systems, leading to a marked increase in matrix stiffness. Although substrate stiffness is known to increase cell migration in cancer and stromal cell populations, it is not well understood how it affects benign epithelial cell motility, particularly within the pelvic cavity. We used an endometriotic epithelial cell line and polyacrylamide hydrogels with tunable stiffness--with glass as an extreme stiffness reference--to model mechanically driven single-cell and multicellular migration. We found that stiff substrates promoted cell speed, actin stress fiber formation, focal adhesion presentation, and spheroid expansion compared to the soft substrate. Increasing cellular contractility on the soft substrate and decreasing contractility on the stiff substrate led to an increase and decrease in cell speed, respectively. These findings provide mechanistic insight on how fibrosis as a biomechanical state regulates epithelial cell migration, with additional relevance to the pathogenesis of benign yet invasive conditions.